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Marine Habitat Committee

REPORT OF THE

ICES CM 19981E:5Ref.: ACME

tJlo

WORKING GROUP ON THE EFFECTS OF EXTRACTION OFMARINE SEDIMENTS ON THE MARINE ECOSYSTEM

Haarlem, The Netherlands20-24 April 1998

This report is not to be quoted without prior consultation with theGeneral Secretary. The document is areport of an expert groupunder the auspices of the International Council for the Exploration ofthe Sea and does not necessarily represent the views of the Council.

International Council for the Exploration of the Sea

Conseil International pour l'Exploration de la Mer

Palregade 2-4 DK-1261 Copenhagen K Denmark

bookeye

Thünen


Section

Table of Contents

ICES CM 19981E:5

Page

INTRODUCTION .

2 TERMS OF REFERENCE 3

3 REVIEW OF NATIONAL MARINE AGGREGATE EXTRACTION ACTIVITIES.................... 4

3.1 Belgium.............................................................................................................................. 43.2 Canada...... 43.3 Denrnark...................................................................... 43.4 France................................................................................................................................. 53.5 Finland................................................................................................................................ 53.6 Germany............................................................................................................................. 53.7 Ireland 53.8 The Netherlands................................................................................................................. 53.9 Norway............................................................................................................................... 73.10 Poland................................................................................................................................ 73.11 Sweden... 73.12 United Kingdom................................................................................................................. 7

4 REVIEW OF NATIONAL SEABED RESOURCE MAPPING PROGRAMMES.......................... 9

4.1 Belgium.............................................................................................................................. 94.2 Canada............................................................................................................................... 94.3 Denmark............................................................................................................................. 94.4 France................................................................................................................................. 114.5 Germany............................................................................................................................. 114.6 The Netherlands................................................................................................................. 114.7 Norway............................................................................................................................... 164.8 Poland................................................................................................................................. 164.9 Sweden............................................................................................................................... 164.10 United Kingdom................................................................................................................. 17

5. REVIEW OF APPROACHES TO ENVIRONMENTAL IMPACT ASSESSMENT ANDRELATED ENVIRONMENTAL RESEARCH 21

5.1 Belgium 215.2 Denmark............................................................................................................................. 215.3 France................................................................................................................................. 245.4 Germany 245.5 The Netherlands 255.6 Norway............... 275.7 Poland 275.8 Sweden................................................................................................. 275.9 United Kingdom................................................................................................................. 27

6. REVIEW OF DEVELOPMENTS IN NATIONAL AUTHORIZATION ANDADMINISTRATIVE FRAMEWORKS AND PROCEDURES....................................................... 31

6.1 Belgium......................................................................................................................... ..... 316.2 Denmark............................................................................................................................. 316.3 France................................................................................................................................. 326.4 Tbe Netherlands.................................................................................................................. 32

lCES - WGEXT April 1998

Marine Habitat Committee ICES CM 1998/E:5

6.5 United Kingdom................................................................................................................. 32

7 CO-OPERATIVE RESEARCH REPORT... 34

8 REVIEW OF INFORMATION ON THE BALTIC ECOSYSTEM..................... 34

9 NEW TECHNOLOGY FOR HIGH RESOLUTION SEABED CHARACTERISATION............ 34

10 RECOMMENDATIONSIDRAFT TERMS OF REFERENCE.. 34

11 CLOSE OF THE MEETING 35

ANNEX I

ANNEX II

ANNEXIII

ANNEX IV

ANNEX V

AGENDA

TERMS OF REFERENCE

LIST OF CONTRIBUTORS TO THE REPORT

SUPPLEMENTARY MATERIALS FOR INCLUSION IN THE REPORT OF THEMEETING

ltem 1 van Dalfsen and Essink. The effects On macrozoobenthos of subaquaeous sandextraction North ofthe island ofTerschelling, The Netherlands.

ltem 2 Nielsen. Monitoring of dredging activities on Kriegers Flak, Balic Sea.

ltem 3 Stottrup et al. Is there a case for artificial reefs in Denmark?

ltem 4 Stottrup and Stokholm. Deployment of artificial reefs for stock enhancement oflobster and protection of nursery grounds for marine fish.

Item 5 Shell Extraction in The Netherlands: ecological effects and policy development.

Item 6 Kenny. A biological and habitat assessment of the seabed off Hastings, SouthemEngland.

DOCUMENTS REVEIWED DURING DlSCUSSIONS ON THE EFFECT OF MARINESEDIMENT EXTRACTION OON THE BALTIC

ltem 1 Letter from Chairman ACME.

ltem 2 Letter on 1997 HELCOM EC Meeting with attachment from ICES Secretariat.

Item 3 Background document conceming marine sand and gravel extraction in the BalticSea produced by Germany for HELCOM EC.

ltem 4 HELCOM RECOMMENDATION 19/1 of 26 March 1998 regarding MarineSediment Extraction in the BaItic Sea Area.

Item 5 1997 Review of the effects of extraction of marine sand and gravel On the Balticecosystem.

/CES-WGEXT ii April /998

• Marine Habitat Committee ICES CM 19981E:5

REPORT OF TIIE WORKING GROUP ON TIIE EFFECTS OF EXTRACTION OF MARINESEDIMENTS ON TIIE MARINE ECOSYSTEM

April 1998

I INTRODUCTION

The Working Group was welcomed to lIaarlem by Dr H Speelman (Director, Netherlands Institute ofApplied Geosciences, NITG-TNO) and Ir D Tromp (lCES delegate for the Netherlands). Dr S J deGroot outlined the role and function of the Working Group stressing the importance of the multidisciplinary composition ofthe group. Ir Tromp opened the Workshop on Large Scale Sand Extractionin the Coastal Zone of the Netherlands and welcomed the Working Group's attendance andparticipation in this meeting.

Ir Tromp emphasised that no decisions had yet been taken on the three major coastal projects that werethe subject of discussion ofthe Workshop and placed them in the national context where the 3 criteriathat were paramount to decision making on these were the importance of environmental considerations,the lack of space on land and the demands of economic gro....th.

Professor Marcel Stive (Delft Hydraulics) summarised the present options for an offshore islandairport. This would involve the creation of an artificial island requiring the extraction of some 500 600 X 106 m] of sand. Most of this might be extracted from the deepening and widening of thenavigation channel to Amsterdam harbour (11 Geul) but a significant amount would have to beextracted from other Iicenced sites. A range of alternatives for the project have been underinvestigation and Professor Stive summarised some of the hydaulic and environmental investigationsalready carried out at this preliminary stage.

Ing Gijs Berger described the 3 principal options for the extension to Rotterdam harbour (Maasvlakte2). An environmental impact assessment was initiated in 1997 and in addition to the land reclamationproject favoured, the optimisation of the existing port area and the use of space in SW Netherlandswere also being considered. The land reclamation option has 2 alternatives requiring the extraction of400 or 600 x 106 m] respectively. The land-based extraction ofmaterial might account for some 150300 x 106 m] , and the widening and/or deepening ofthe Euro Maas channel may yield a further 300 x106 m] but additional material would have to be taken from Iicensed marine sites. With the presentrestriction of a sediment extraction depth of 2m some 200 km2 may require Iicensing. An alternativescheme allowing extraction to 10m would reduce this to 40 km2

•

Drs Jan van Dalfsen (National Institute of Coastal and Marine Management) reviewed theenvironmental effects associated with such large scale extraction projects, examining impacts on thewater column and benthos. A number of the potentially longer term effects were being examined andaddressed but further work would be needed.

Prof Wim VIasbIom (Delft Technical University) reviewed the use of both trailing hopper suctiondredgers (THSDs) and sea going suction dredgers (SGSDs). He concluded that by either system theextraction operations on the scale envisaged were possible. He discussed the differences in likelyenvironmental effects from both forms of extraction and highlighted the possibility for using gradualsloping sides to areas where sediment extraction to a depth greater than 2m below the seabed may bepermitted.. With regard to increased turbidity levels he cited work undertaken in Hong Kong("Suspended Solids Concentrations in Dredging Plumes", Final Report, Geotechnical EngineeringOffice, Civil Engineering Department, demas, The Netherlands, October 1995) which suggested 15 x106 m] of silt fines may arise from an extraction of 175 x 106 m] of sediment. One possibility forreducing sediment losses is to redirect the overflow water to the draghead, but this requires furtherinvestigation.

Of the three proposed projects Maasvlakte 2 (main port Rotterdam) and the extension of main portSchiphol were discussed in detail. The third project is the reclamation of an area between Book ofHolland and the Hague. Tbe laUer has the lowest priority but would involve consideration of manY ofthe same issues.

leES - WGEXT April 1998

Marine Habitat Committee lCES CM 19981E:5 ..

There was a detailed discussion on a number ofpoints ranging from natural bedform dynamics and theextent of natural disturbance of the benthos, to specific effects on fisheries and the effects of beamtrawling on the benthos. Results from the studies to date suggest that the longer terms effects on theWaddensee were likely to be negligible, and thus attention had focused rather more on the short termopen coast effects of the reduction in primary production, and other impacts associated with sedimentplumes over the comparatively long timescales during which dredging would occur.

The Working Group expressed its thanks for being able to participate in the Workshop and Ir Trompthanked the ICES Working Group members for their contribution to the discussions. All agreed thatsuch large scale projects required special attention and consideration by the scientific community.ICES ACME might wish to consider the localised and transboundary environmental effects of theproposed projects as a topic for a theme session at a forthcoming ICES Annual Science Conference.

Dr S J de Groot opened the 1998 meeting, the terms of reference (see below) were adopted and Dr JSide was appointed as Rapporteur for the meeting. Dr S J de Groot, in accordance with the ICESdecision (letter of 30 March 1998, C Hopkins, General Secretary Ref C:8.r/CH/mm) announced that hewould be standing down as Chairman of the Group at the conclusion of the 1998 meeting. He invitedthe Group to consider the nomination of a new Chairman which could be recommended to ICESMarine Habitats Committee/ACME together with the other recommendations ofthe Working Group.

For a number of reasons, but mostly owing to illness, some regular contributors to the annual meetinghad sent apologies for not atending. These were Dr C Augris (France), Dr G Fader (Canada), Dr DHarrison (UK), Dr R Keary (Ireland), Mrs B Lauwaert (Belgium) and Dr Heiko Leuchs (Germany).New members ofthe Working Group were welcomed by all attending.

lCES-WGEXT 2 April 1998

• Marine Habitat Committee

2 TERMS OF REFERENCE

ICES CM 19981E:5

The Working Group on the Effects of Extraction of Marine Sediments on the Marine Ecosystem(WGEXT) (Chairman: Dr. S. de Groot, The Netherlands) met in Haarlern, The Netherlands from 21-24April 1998* to:

a) fmalize the ConclusionslRecommendations of the ICES Cooperative Report (see ICES CM1997/E:4), and review the final revisions ofall other sections (to be available at the beginningof June 1997);

b) collect further information on the effects of extraction of marine sand and gravel on the Balticecosystem, including the extent and volume of such extractions, and known impacts on, e.g.,benthos, diving seabirds and bottom-spawning fish and invertebrates with the understandingthat a combined meeting of WGEXT members with members from HELCOM EC NATUREwill take place in one of the BaItic countries in 1999;

c) review and report on developments in new technology for high resolution seabedcharacterization such as micro- and macro-topography, complex sediment distribution andprocess interpretation (these developments provide the essential data for sustainabledevelopment ofresources and the definition ofhabitats in the coastal zone);

d) review and report on the results of environmental research on the effects of turbidity causedby dredging or large-scale natural erosion;

e) review and report on the status of marine sediment extraction activities (in relation to 'use'categories), the development of seabed resource mapping, and developments in legal andadministrative framework and procedures.

The Working Group will report to the ACME before its June 1998 meeting and the Marine HabitatCommittee at the 1998 ASC.

* WGEXT members were invited to take the opportunity to discuss and appraise three proposedextraction projects (each about 800 x 106 mJ of sand) in the Dutch Coastal Zone and to meet withrepresentatives of the regulatory authorities and dredging companies on 20 April 1998.

ICES-WGEXT 3 April 1998

Marine Habitat Committee ICES CM 19981E:5

3 REVIEW OF NATIONAL MARINE AGGREGATE EXTRACTION ACTIVITIES

3.1 ßelgium

In 1997 extraction mainly took place at the northern part of the Kwintebank as in previous years.Dredging activities have been monitored by a black box (electronic monitoring) system since 1/1/1997.Data have not yet been made available by the Ministry.

Additional extractions under temporary Iicences for the extraction of about 2 x 106 m3 of sand andgravel have been carried out to obtain material for covering two new gas pipelines. Construction ofthetwo pipelines has been completed.

3.2 Canada

No new information to report.

3.3 Denmark

The extraction of marine sand and gravel represents 10-13 % of the total production of materials forconstruction and reclamation. The amount of materials dredged for construction has been increasingslightly from 1992 until1995 since when a slight decrease has been seen.

The dredging of sand fill for land reclamation has increased markedly over the last 10 years as a resultof several large construction works in coastal areas. From 1989 to 1993 more than 9 x 106 m3 of sandfill and tiII have been dredged for the construction of the Great Belt bridge and tunnel projecl. Theconsumption of sand for beach replenishment at the west coast of Jytland has shown a pronouncedincrease from 40,000 m3 in 1980 to more than 3 x 106 m3 in 1997.

During the construction of the fixed link between Denmark and Sweden up to 3 X 106 m3 of sandfillwiII be dredged from the Kriegers Flak in the Baltic. The dredging started in January 1996 and thisactivity is expected to last 4 years. Until now 1.1 x 106 m3 has been dredged. During this period up to 7x 106 m3 dredged materials of glacial tiII and limestone wiII be used for reclamation and as hydraulicfill in ramps for the bridge and tunnel.

A major enlargement ofthe harbour of Arhus is expected to require more than 3 x 106 m3 of sand fill inthe next two years. The construction works will start in the autumn of 1998.

Sand Granl Granl/Stones Mise.Year 0-2 rn rn 0-20 rnm 6-300 rnrn Sand fill (TiII)

1990 1.0 x 106 m3 0.2 x 106 m3 0.6 x 106 m3 3.9 x 106 m3 0.1 x 106 m3

1991 1.1 xl06 m3 0.5 x 106 m3 0.9 x 106 m3 4.4 x 106 m3 1.0 x 106 m3

1992 0.7 x 106 m3 0.5 x 106 m3 0.9 x 106 m3 1.2 x 106 m3 0.8 x 106 m3

1993 0.9 x 106 m3 0.2 x 106 m3 1.1 x 106 m3 2.1 x 106 m3 0

1994 1.1 x 106 m3 0.2 x 106 m3 1.3 x 106 m3 2.6 x 106 m3 0

1995 1.1 x 106 m3 0.2 x 106 m3 1.2 x 106 m3 2.8 x 106 m3 0.3 x 106 m3

1996 0.9 x 106 m3 0.2 x 106 m3 1.1 x 106 m3 4.0 x 106 m3 2.2 x 106 m3

1997* 0.5 x 106 m3 0.2 x 106 m3 1.5 x 106 m3 4.0 x 106 m3 2.1 x 106 m3

* The figures from 1997 are prehmmary.

No detailed forecast for the future extraction has been prepared but it is expected that the exploitationof marine sand and gravel wiII inerease at the expense of land materials. This is mainly based on theexpeeted termination of a number of Iieenees on land and inereasing environmental eonfliets inpotential extraetion areas on land.



3.4 France

lCES CM 19981E:5

Produetion has been very stable in Franee from 1990 to 1995, being 3.92, 3.99, 3.70, 3.45, 3.67, and3.66 xlO6 tonnes respeetively. Produetion in 1996 and 1997 has stabilised at around 3.6 xl06 tonnesper annum. Produetion from calcareous deposits is about one fifth that of silieeous aggregates.

3.5 Finland

No new information on extraetion aetivities available.

3.6 Germany

North Sea

The greatest amount of sediment extraetion derives from maintenanee dredging within the waterwaysinside estuaries. This has resulted in an annual dredging and dumping figure ranging between 45 and55 million tonnes from estuaries. In 1997, sand extraetion has been eontinued for eoastal proteetion ofthe island of Sylt. The extraetion pit is situated 7 km west off Sylt at a water depth of 14 m. Maximumextraetion volume is Iimited to 2 million m3 per year. Commercial sand extraetion is planned for thearea ofthe Weisse Bank.

Baltic Sea

No extraetion of marine sediments has taken plaee during the last 10 years on the eoastal shelf ofSchleswig-Holstein, and no extraetion is eurrently planned. On the eoastal shelf of MeeklenburgVorpommem there are aetually 17 extraetion fields for which permission has been granted by nationalauthorities. The majority of the extraction sites are used for eoastal defenee purposes. These sites arenot permanently exploited but only periodically, where there are coastal defence projects executed inthe respective region. From four fields sand and gravel is used as construction material (eonereteproduetion, fiIIing material, road eonstruetion ete.). These fields are: sea area off Kühlungsbom,Greifswalder Bodden, Adlergrund and Plantagenetgrund.

Year Aggregate Extraction(m3)*

1992 372,0001993 468,0001994 814,0001995 919,0001996 2,158,0001997 2,269,000

TOTAL 7,000,000• Baltle Sea only

3.7 Ireland

The Geologieal Survey of Ireland reported (via BGS) that there is currently only one existing Iieencefor sand and gravel extraction in Irish waters issued by the Department of the Marine and NaturalResourees. The Iieensed area is off Wexford, S EIreland, but there has been no eommercialproduetion from this site to date.

3.8 The Netherlands

Sand Extraction 1997

The amount of sand extracted from the North Sea in 1997 was as folIows:

Euro-/Maas access-channel to Rotterdam 8.3 x 106 m3;


Marine Habitat Committee lCES CM 19981E:5

U-access-channel to Amsterdam 4.2 x 106 m3;

Dutch Continental Shelf 10.3 x 106 m3;

Total sand extraction in 199722.8 x 106 m3; and

About 1.4 106 m3 has been dredged on the Dutch shelf and used on the UK shelf for cableprotection.

The main applications of the extracted sand are for the beach nourishrnent programme and for land uses.In 1997 approximately 7.9 x 106 m3 was used for beach nourishment and approximately 13.5 x 106 m3 wasused mainly for land fill.

A desk study has been published (DWW,1997) with an estimation ofthe demand for sand from the NorthSea for the period 1996 to 2030. In this report the sand demand is given for aminimum, a mean and amaximum scenario. The total demand for the period 1996 to 2030 is 919 x 106m3 for the minimumscenario and 1736 x 106m3 for the maximum scenario. The expected sand demand for the mean scenariois:

589 x 106 m3for fill;432 x 106 m3 for beach nourishment; and150 x 106 m3 for construction purposes.

Gravel Extraction 1997

In 1997 no extraction of gravel took place in the Dutch part of the North Sea. Due to the Dutch policy onextraction of surface minerals as written down in Structure Plan for Surface Minerals, extraction on theCleaver Bank will not be permitted before the termination of the gravel extraction carried out inconjunction with the lowering of the winter bed of the River Maas. This policy is part of the expectedpeak in the extraction of gravel in the south-east of the Netherlands (Limburg) as a result of theimplementation ofthe Delta Plan for the Major Rivers. The effects ofthis plan will lead to a production ofrelatively high quantities ofgravel in a short period oftime (up to 2005). The total available quantities willincrease from 35 to 60 million tonnes due to these works.

Shell Extraction 1997

The total amount (x 103 m3) of shells extracted from the Wadden, North Sea and Intemal Waters from

1990 till 1997 was as folIows:

Table I: total amount of shells (x 103 m3) extracted out of:

the Wadden Sea and sea-inlets ofthe North Sea (grey shaded)

1990 1991Wadden Sea 63.805 51.630Sea~iillets:f;: ",: .lj:'l;l6~ii:"i83aa5~;:

Total 130.970 135.365

1992 1993 1994 199589.285 90.394 125.755 117.511

.82.460;: ii~(l;396i.,;:,\'19;'iB;:i .78\111~~\':

171.740 170.790 205.470 195.685

1996103.770

169.310

1997

135.936

Tabel2: total amount of shells (x 103 m3) extracted out of:

the south-west part (Zeeland) and the North Sea (grey shaded)

1990 1992 1991 1993 1994 1995Eastern Scheldt 12.524 0 490 1.475 5.575 300Western Scheldt 15.802 25.175 21.225 14.390 4.158 26.850iyoordelta!i;i':;;;:'~;~\~\:: ~ 11:l$~,)fl)'.\,1~:~15\: .I(l,97~,i~ .2~a$Q ..::;i;A~;759"i;\; 20;5QS;i,,!Total 49.608 37.590 32.690 39.615 16.483 47.655

1996750

21.025

44.275

1997o

76.755

From 1999 onwardsnew maximum permissible amounts for the extraction ofshells will be defined.

ICES-WGEXT 6 Apri/1998


3.9 Norway

lCES CM 19981E:5

In 1997, as in the preceding year, very small amounts ofmarine sand and gravel have been extractedfor constructional purposes in Norway.

Carbonate sand extraction is expected to have been exploited at about the same amount as in previousyears (100,000 - 150,000 tonnes), although there are no published statistics ofthe carbonate sandextraction during 1997 and 1998. This is due to insufficient reporting arrangements for the extractedvolumes.

3.10 Poland

In 1997 about 1,900 tonnes of gravel were extracted from the Slupsk Bank area on the Polish ExclusiveEconomic Zone (EEZ). A further 252,000 m3 of sand were extracted from the seabed for beachnourishment in 1997 on the Hel Peninsula. In 1997 about 1,641,500 m3 of sand was identified andgeologically documented for beach nourishment in the western part ofthe Polish EEZ (in the vicinityofDziwn6w).

3.11 Sweden

There were no marine aggregate extraction activities in 1997.

3.12 United Kingdom

Production in the UK in 1997 fell to 24.8 x 106 tonnes from 26.6 x 106 tonnes in 1996. Demand formarine aggregates for construction and export was fairly flat in 1997. The drop in total extraction wasaccounted for by a decline in the quantity of beach recharge material. Regional summaries are shownbelow:-

Marine Aggregate Extraction in 1997

Dredging Area TonnageHumber 2,351,233.00East Coast 9,397,705.00Thames Estuary 1,125,921.00South Coast 4,733,824.55South West 2,048,014.29North West 284,497.00Rivers and Miscellaneous 18,587.30Total 19,959,782.14

Licences specifically for fill contracts and beach replenishments were as follow:-

EnglandTotal

4,916,725.5024,876,507.64

In 1997, 13 x 106 tonnes were used by the construction industry mainly for concrete. 6.8 x 106 tonneswent for export primarily to the Netherlands and Belgium with smaller quantities to France andGermany.

UK Exports of Marine Sand and Grayel 1997

Port Tonnage

Amsterdam 2,488,222.00Antwerp 837,532.00Brest 23,761.00Brugge 345,030.00

leES - WGEXT 7 April 1998

llJarine Habitat Committee

Calais 128,394.00Dunkirk 605,536.00Fecamp 45,270.00Flushing 780,922.00Hamburg 66,594.00Harlingen 332,188.00Honf1eur 74,991.00Nieuport 294,879.00Ostend 305,085.00Roseoff 37,980.00Rotterdam 29,988.00St. Sampson 6,172.00Treguier 33,397.00Vattevill 3,853.00Zeebrugge 439,098.00Total 6,878,892.00

ICES CM 19981E:5

Marine sand and gravel continued to supply about 15% of the total demand in Great Britain during1997, the main areas of use being concentrated in the South East principally London, the ThamesEstuary and the South coast East ofthe Isle ofWight and the South West.

There was no calcareous seaweed extracted from the Crown Estate land in 1997 although a limitedamount of extraction did take place in the Falmouth Estuary under the ownership of the local HarbourCommissioners in 1995. A limited amount of waste coal was extracted. Very small quantities ofmarine sand and gravel were extracted from non-Crown land.

Marketing of Marine Aggregate is becoming ever more complicated. Companies are now husbandinggood quality gravel reserves by blending it with lesser quality material at as many wharves as possibleso that an acceptable material is made available for the widest possible market. This trend is likely tocontinue as on board treatment ofcargoes becomes more difficult/expensive.

The aggregate demand forecast for England in the fifteen year period 1992 to 2006 inclusive is givenin MPG6 (Mineral Planning Guidelines, No 6), published by the DoE in April 1994. For marine sandand gravel the demand in England (excluding coast protection and exports) only averages 21 milliontonnes per year for the fifteen years. In the last six years only 60% ofthe forecast demand was landed.

Current Licence Position Summary UK - Summary

• 317 million tonnes total reserve of sand and gravel within UK dredging licences.• 308 million tonnes in the Govemment View Procedure.• 255 million tonnes ofpossible sources identified by prospecting.• 14 current prospecting licences.• 32 applications currently in the Govemment View Procedure.• 78 areas licensed by the Crown Estate for marine aggregate dredging.

Scotland

Periodic extraction of very small volumes ofsand occur in the River Tayrray Estuary and in Spey Bay.Up to 4,000 m3 ofmaerl is extracted annually from Wyre Sound in Orkney. Extraction is from an areawhere dead maerl material is accreting and material is being used for specialised waste waterpurification and biological filtration applications rather than for general agricultural use.



4 REVIEW OF NATIONAL SEABED RESOURCE MAPPING PROGRAMMES

4.1 Belgium

Tbe Ministry of Economical Affairs, commisioned a geomorphological and sedimentological researchprogramme (Westbank), which started in 1990. So far bathymetric measurements (single beam), sidescan sonar and sedimentological sampling (Van Veen) have been carried out. Tbe programme iscurrently in its third phase.

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4.2 Canada

No new information to report.

4.3 Denmark

Tbe National Forest and Nature Agency has commissioned the Geological Survey to undertake anevaluation ofthe total reserves ofsand and gravel in Danish \Vaters based on all existing data collectedsince 1979. Tbe calculation of the reserves is based on known technical limitations (Le. overburden)and present environmental restrictions. All identified resources in the Inner Danish Waters have nowbeen evaluated. Tbe present knowledge ofthe resources and the environmental conditions in the NorthSea is very incomplete and will only allow an evaluation of selected areas. An overview of the resultswill be published during 1998.

Mapping of the sea bed is an integrated part of the systematic reconnaissance resource mappingprogramme in Danish Waters. The mapping programme continues and is concentrated in the NorthSea, Kattegat and the Baltic. Since 1991 mapping programmes have been carried out on Jutland Bankand Horns Reef in the North Sea and in Ferner Baelt, Adler Ground, Ronne Banke and Kriegers Flak inthe Baltic. l\1aps (scale 1: 100,000) of surface sediments, Quaternary geology and sand and gravelresources have been prepared. At present, between 80 % and 90 % of potential resource areas in theInner Danish Waters have been mapped. In 1997 a reconnaissance mapping was carried out in greaterwater depths in the central part of Kattegat and in the North Sea.

Detailed resource mapping programmes have been carried out in some regional extraction areas withmaterials ofhigh quality and in areas Iicensed for bridge and tunnel projects.

In 1997 detailed sea bed mapping has been carried out for a possible fixed link between Germany andDenmark in the Ferner Belt between Putgarten and Roedby.

Small scale seabed mapping programmes have been carried out in relation to applications for dredgingpermits, e.g. in the Bay of Aarhus, Kattegat and North Sea.

A map of the surface sediments in the Danish part of the Sound (scale I: I00,000) was published in1990.

An overview map ofthe bottom sediments around Denmark and western Sweden (scale 1:500,000) hasbeen published in 1992 in a co-operation between the National Forest and Nature Agency, theGeological Survey ofDenmark and the Geological Survey ofSweden.

A detailed map of the Flensborg Fjord area was published during 1994 by the Geological Survey ofDenmark.

A surface sediment map from the Ferner Baelt - Arkona Basin (scale I:200,000) was published in 1996by the Geological Survey.

Surface sediment map from Jytland Bank, North Sea will be published in 1998.

Some ofthe most important stone reefs in Danish waters have been mapped 1990-1996 using shallowseismic equipment, side scan sonar, SCUBA-divings and sampling. Tbe project is a co-operative one

/CES-WGEXT 9 April /998


between the National Forest and Nature Agency, the Geological Survey of Denmark and University ofCopenhagen. Two reports have been published so far. Tbe reports include surface sediment maps,gravel and stone concentration maps and descriptions ofthe biology in the areas.

Figure 4.1 Mapping programme in Danish Waters. Dark shaded areas indicate where surface sedimentmaps have been prepared during the reconnaissance mapping programme (unpublishedand published data).

SWEDEN

Data Reports

Supplerende seismiske undersogelser i omräde 524, Horns Rev. DGU rapport nr. 76. 1993.

Rästofgeologiske og geologiske undersogelser i Ostersoen. Ferner Breit, omräde 564. GEUS rapport1996.

Seabed Sediment Maps

Overfladesedimenter iden danske dei af Oresund I:100.000. (Surface sediments in the Danish part ofthe Sound 1: I00.000).

Compiled by: A. Kuijpers, B. Larsen, P.E. Nielsen. Published by: National Forest and Nature Agencyand Geological Survey ofDenmark, Ministry ofthe Environment ofDenmark 1990.

Bottom Sediments Around Denmark and Western Sweden. Compiled by: Kuijpers, A., Nielsen, P.E.,Larsen, B., Cato, 1., Kjellin, B., Jensen, J.B., Leth, J.O., Nowak, B. and Nielsen, T. Ministry of the Environment, National Forest and Nature Agency and Geological Survey ofDenmark, Geological Survey ofSweden, 1992.

Sedimentkort over Flensborg Fjord/Sedimentkarte der Flensburger Förde. DGU Map Series Nr. 46.Geological Surrvey of Denmark, Geologisch- Paläontologisches Institut der UniversitätKiel,1994.

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1CES-WGEXT 10 April 1998


',' ..... 'J .... ".~. 'I .. I', :": 10,."'." ',.,"

lCES CU 19981E:5

•

Geologisk kort over Danmark, Kortbladet Ferner BreIt - Arkona Bassinet - Geologische Karte vonDänemark, Blatt Fehmarn Belt - Arkonabecken. 1: 200.000. J.B. Jensen, A. Kuijpers & W.Lemke. Danmarks Geologiske Undersogelse, Map Series No. 52, 1996.

Sediment Map, North Sea NE. J.O. Leth. Geological Survey ofDenmark, 1998 (in print)

4.4 France

IFREMER is continuing its programme of seabed mapping on the shelf of Martinique (French WestIndies), on the continental shelf of the northern part of the Basque country (Atlantic shelf) and on thecontinental shelf of the Gulfof Lions (Mediterranean Sea). In 1997 IFREMER published:-

Bathymetry and Physiography ofthe Channel approaches western margin(Scale: 1:250,000)Bathymetric synthesis ofthe western Mediterranean Sea(Scale: 1:250,000)

4.5 Germany

A resource mapping of movable sands has been performed along the North Sea coast by theBundesamt fuer Seeschiffahrt und Hydrographie (BSH). A high-resolution survey was conductedresulting in 2220 NM of seismic profiles. Furthermore, 21 vibrocores were retrieved giving insight intoupper 6 m of sediment column. Results will be available at the end of 1998.

German Area ofthe Baltic Sea (Mecklenbur~-Vomommern)

A survey of marine sand and gravel deposits has been performed on behalf of governmental authorities(Staatliches Amt fLlr Umwelt und Natur Rostock) from 1992 to 1997 in order to identify extractionfields for coastal defence measures. The exploration was done by a private company (UWGGesellschaft rur Umwelt- und Wirtschaftsgeologie mbH Berlin). The final result was the designation of19 extraction fields along the entire coast ofMecklenburg-Vorpommem. A map and the positions havebeen published (Figure 4.2) in "Amtsblatt rur Mecklenburg-Vorpommern 1997, Nr.54 pp1327 Richtlinien für die Erteilung von Bergbauberechtigungen und zur Zulassung von Hauptbetriebsplänenrur die Aufsuchung und Gewinnung von marinen Sanden im Bereich der Küstengewässer und desFestlandsockels des Landes Mecklenburg-Vorpommern rur Strandaufspülungen undKüstenschutzmaßnahmen (Richtlinie marine Sandgewinnung rur Küstenschutz -RL-MSK-)".Ecological investigation ofthese fields has not been undertaken yet, but is planned for the near future.

4.6 The Netherlands

Resource mapping is the responsibility of the national geological survey. The Survey has become acomponent body of the national applied science and technology conglomerate TNO. Its present nameis 'Netherlands Institute of Applied Geoscience TNO, national geological survey'.

A review of the progress in the field of seabed resource mapping in 1996/7 is presented below.Corresponding maps that show the progress of the mapping programmes are shown in Figure 4.3 andFigure 4.4.

1:250,000 geological reconnaissance map series

This map series consists amongst others ofa surface geology (sea bed sediments) sheet which includesa main map in UTM on scale 1:250,000 showing the uppermost 10 cm of the seabed following theFolk c1assification system and various subsidiary maps. These maps on ascale of 1:100,000 include:the seismic line grid; thickness of a Holocene sediments, depth to the base of the Holocene sediments,distribution of (older) Holocene formations; mean grain size; biogenie and lithic gravel content and/orcarbonate content of sand fraction; geochemistry of surface sediments (Oyster Grounds map); a key tocolours and symbols and a short description. Each mapped area covers 10 latitude and 20 longitude.

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All the sheets of the 6 mapped areas are now available in digital fonnat. The seabed sediment map ofTerschelling Bank (53-54"N, 4-6°E) is in prepation.

"'i'1:100,000 gcology & rcsource map scrics

This map series consist of sheets with both geological and resource infonnation.

The geological component includes: a fence diagram with the geological structure of the youngerlayers (1:100,000); a bathymetric map at 1:150,000; 1:250,000 maps on geomorphology; on theoccurrence of Bolocene fonnations; on thickness of Bolocene and of Pleistocene deposits; a fencediagram of older sediments; nature and depth of the top Pleistocene and of the top Tertiary and a shortdescription a.o. ofthe stratigraphie units.

The resource component includes a map of the mean grain size and mud content of the uppennostmetre on 1: 100,000, a similar map of the metre below on a scale of I: 150,000 and 1:250,000 scalemaps on the carbonate content in the first and the second metre, on Iithic and biogenie gravel contentsin the first and second metre, and on interfering (c1ayey) layers in the first and in the second metre anda short note on methodology, sediment c1assification and on the availability offurther infonnation.

The map sheet Buitenbanken (51° 40'-52"N, 3-3° 40'E) was printed in 1996. Schouwenbank (51° 40'52"N, 3° 40'-4° 30'E) is available in digital fonn only like all forthcoming sheets while the Indusbank(52-52° 20'N, 3° 50'-4° 30'E) and IJmuiden Ground (52° 20'-52° 40'N, 4-40 40'E) sheets are in variousstates of completion. Data acquisition programmes on two sheets more to the north are currently underway.

Applied Geolozical Investizations in 1996/7

As in previous years various beach nourishment schemes led to extraction site surveys.

Continuous demand for the latest infonnation on ofTshore sand resources necessitated the updating ofexisting syntheses on both the nature and suitability of sands down to 4 m below seabed in a 50 kmwide belt ofTthe Netherlands coast.

Several studies were being carried out to evaluate extraction sites for Rotterdam harbour extensionschemes (the Maasvlakte 2 project). In the same general area the potential resources for concrete andmortar sand were evaluated.

Geochemical Maps

Geochemical distribution maps ofsurface sediments, as outlined in an earlier ICES progress report, arebeing prepared for the 1:250,000 scale Terschelling Bank sheet. Moreover, to facilitate correlationswith existing BGS work, sampIes taken along the UKJNL median \ine are being analysed.

Reports

Frantsen, P.J. & Zwanenburg-Nederlof, B.P., 1998. De Fonnatie van Kreftenheye in de blokken PI6,PI7 and PI8. Onderzoek naar winbare voorkomens beton- en metselzand zuide\ijk deel NCP,(the Kreftenheye Fm in blocks PI6-PI8. concrete and mortar sand resources survey in thesouthern part ofthe Dutch continental shell), Rept. NITG 98-245-ß (in Dutch).

Klugt, P.C.M., van der, 1997. Grofmazig grondonderzoek externe zandwinlokaties Maasvlakte 2Deelrapportage boonnonsterbeschrijving, (Extensive soil survey external sand extractionlocations Maasviakte 2 project, Rept. NITG 97-242-B (in Dutch).

Klugt, P.C.M., van der, 1997. Onderzoek zeezandwingebied nabij Ameland B10k M81M9, (sandextraction area survey near Ameland), Rept. NITG 97-20-ß (in Dutch).

leES - WGEXT 15 April/99B


Kok, P.T.J., 1997. Onderzoek schelpvoorkomens binnen de -20 m diepteIijn, (shell layer occurrenceswithin the -20 m depth contour), Rept. NITO 97-225-B (in Dutch).

Kok, P.T.J., 1997. Onderzoek schelpvoorkomens in het Waddenzeegebied, (sheII layer occurrences inthe Wadden Sea area), Rept. NITO 97-244-B (in Dutch).

Zonneveld, P.C., 1997. Onderzoek in het zandwingebied M9D ten Noorden van Ameland in deNoordzee, ( survey in the North Sea sand extraction area M9D, north of Ameland), Rept.NITO 98·65-B (in Dutch).

4.7 Norway

An investigation of both the sand and gravel and carbonate sand resources in the the coastal areas ofthe county Troms, Northern Norway, has been carried out. An overview ofmapped areas is providedin Figure 4.5.

4.8 Poland

The following mapping programme was completed in 1997.

Detailed geological-geodynamical mapping ofthe coastal zone (I: 10,000).

The aim of this project was to investigate the geological background to the evolution of the coastalzone. The first stage of this project was completed in December 1997 and mapped the coastal zonefrom I km inland to 1.5km offshore. A total of 180km of the coastline has been mapped by 32 sheets ata scale of 1:10,000. The maps present land topography, bathymetry, Iithology of inland and seabeddeposits, coastal erosion hazards, land use, forestry and protected areas etc.

The current programme for the Baltic Sea started in 1996 and will be completed in 1999. The aim is tomap the pre-Quatemary deposits up to between 300 and 600m below the sea bottom for the Polish EEZand adjacent areas. In 1997 about 3000km of seismic profile was undertaken with multichannelequipment. It is planned to undertake a further 3000km of seismic profiling in 1998. The geologicalmaps will be published at a scale of 1:200,000.

4.9, Sweden

During 1997 the Oeological Survey of Sweden continued mapping (at a scale of 1:100,000) of theseabed in the Stockholm archipelago which started in 1995. A new area of about 2,500 km2 wascovered by profiling with side scan chirp sonar, seismic and sub-bottom profiler, coring and grabsampling. Simultaneously both elements and organie micro-pollutants were studied in the superficialsediments. The map ofthe northern part ofthe Swedish sector ofthe Kattegat was published in 1997(SOU Ser Am no 6.). Several publications were finalised covering the trend monitoring studies andcontaminants in the superficial sediments of the Skaggerak and Kattegat (SOU Ser Ca no 86, SOURapp o. Medd no 95).

In a joint Swedish-Lithuanian project (OEOBALT) two new maps at the scale 1:500,000 are beingproduced showing the bathymetry and bottom sediments respectively of the central Baltic Sea. Allcountries around the Baltic Sea have contributed with their most recent data. The maps which providemore detail than existing maps ofthe area will be published at the end of 1998 (SGU Ser Ba no 54) andwill also be available in CD-Rom versions.

Publications

Cato, I. and Klingberg, F. (Eds.), 1997: Proceedings ofthe Fourth Marine Geological Conference: TheBaltic 24-27 October 1995, Uppsala, Sweden. Geological Survey of Sweden SGU Ser Ca 86, pp.185.



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Cato, 1., 1997: Reeent trends in eoastal sediment quality - areport from five trend monitoringprogrammes. Geological Survey of Sweden SGU Rapp. o. Medd. no 95, pp. 386. (In Swedishwith abstracts and summaries in EngHsh).: ..

Gelumbauskaite, L.-Z. (Ed.) (in press): Bathymetric Map of the Central Baltic Sea at aseale of1:500,000. Geologieal Survey of Sweden SGU Ser Ba 54/ Geological Survey of Lithuania.

Repecka, M. and Cato, I. (Eds.) (in press): Bottom Sediment Map ofthe Central Baltic Sea at a scale of1:500,000. Geological Survey of Sweden SGU Ser Ba 54/ Geological Survey of Lithuania.

Rosenberg, R., Cato, 1., ForHn, L., Rodhe, J. and Grip, K., 1997: Vasterhavets miljo - slutrapport. (TbeEnvironment of Skagerrak and Kattegat - final report). Swedish Environment protection AgencyReport no 3096. (In Swedish with English summary).

SGU 1997: Tbe Marine Geological Map Vinga-Kungsbacka at a scale of 1:100,000. Geological Surveyof Sweden SGU Ser Am no 6.

United Kingdom

Marine Aggregates in NW Europe

The British Geological Survey (BGS) was eommissioned in 1997/98 by the Construetion IndustriesResearch and Information Association (CIRIA) to undertake a scoping study to evaluate the factorsthat will influence demand for marine sand and gravel, and the resources to meet this demand, in NWEurope to the year 2025.

Partners in the project included the Netherlands Institute of Applied Geoscience (NITG-TNO) and theGeological Survey of Denmark and Greenland (GEUS). Other key contributors included the Frenchgeological survey organisation (BRGM) and the Geological Survey of Ireland (GSI). Tbe marinedredging industry has made significant contributions to the work, particularly with regard to factorsinfluencing future demand.

Tbe project's report summarises the current state of marine sand and gravel production in NWEurope, and disparities in the amount, the completeness and the quality of the resource inventory indifferent countries. It further identifies additional work that is needed to provide a comprehensivereview of factors that will influence the demand for marine sand and gravel, and the resources to meetthis demand, to the year 2025.

Tbe report recommends the further investigation of a number of demand and resource related topicsincluding:-

Demand issues

1. Tbe reassessment of future demand estimates using different economic gro\\th scenarios.2. To review how national government mineral planning policies might impact on future

demand.3. To study the potential of, and government policies towards the use of, alternative materials

and alternative sources such as superquarries as substitutes for marine sand and graveI.

Resource issues

1. Tbe need for quantification and compatibility ofthe resource inventory in NW Europe.2. Selective new survey work over areas requiring resource assessment.3. Review trends in environmentallegislation and consideration ofthe impacts ofchanges in the

planning and extraction regimes.4. Investigation of the influence of sediment fluxes on the availability and sustainability of

resources.


Jlarine Habitat Committee

Figure 4.5

ICES CM 19981E:5

PUBLISHED QUATERNARY rvlAPS OF THE NORWEGIAN CONTINENTAL SHELF

65'...,

1. Hamborg. M. & Lien. R.. 199-t:VALDER0YA. Quatemary map AO? 105106.Scale 1:20000. Geo!. Survey ofNorwayl Cont.

.Shelf Inst./ Norwegian Hydrographie Servise.

2. Larsen. E.. Klakegg, O. & Longva, 0 .• 1988:BRATTVAG 1220 1Il, Seale 1:50000Quaternary map. Geo!. Surve)' ofNorwa)..

3. Svcian. H. & Bjerkli. K., 198-t:VERDALS0RA. Quaternary map CST135136-20. Geo!. Survey of Norway.

-t. Elverhoi. A. & Solheim. A., 1983: Thephysical environment Western Barent Sea1:500 UOO. Sheet A. Surface sediment

distribution. Norwegian polar Inst., Skrifl.er179A.

5. Solheim, A. & Kristoffersen, Y., 198-t: Thephysical environment Western Barent Sea000. Sheet B. Sediments above the upperregional uneonformity: Thiekness, seismicstratigraphy and outline of the glacial history.Norwegian Polar Inst., Skrifter 1798.

6. Rise, L., Rokoengen, K., Skinner, A. C. andLang, D., 198-t: Northern North Sea.Quaternary geology map benveen 60°30' and62N, and cast of 10E). Seale 1:500000. Cont.Shelf Inst. (IKU).

7. Bugge, T. & Woien, H., 1983: QUJtemarygeology Haltebanken. Sheet 6-tO~

Seale 1:500000. Cont. Shelf lnst. (IKU).

8. Rise, L., Rokoengen, K., Sa:ttem, J. & Bugge.T., 1988: Thickness ofQuaternary deposits onMid-Norway Continental She!f. Sheet seale1:100000. IK.U pub!. nr. 119 (ISSN 0332-5288). Cont. Shelf lnst. .

9. Rokoengen, K. 1980: Shallow geology on MidNorway shelf outside MDre and Romsdal. Seale1:250 000. Cont. Shelf lost. (IK.U).

10. King, L. H., Rokoengen, K. & Gunleiksrud, T.,1987: Quaternary Seismosuatigraphy oftheMid Norwegian Shelf, 65°-67°30' N. - A tilltongue stratigraphy. Pub!. no. 11~ (ISSN 0332·5288). Cont. Shelf lost.

11. Worren, T. & Wassmyr, S. 1991: TheContinental shelf, surficial sediments. Norw.Mapping Auth., Sheet 2.3.8.

12.0uesen, D., Boe, R., Longva. 0., Olsen, H.,Rise. L., Skilbrei.l. and Thorsnes, T., 1996:Geologieal atlas· Skagerrak. Atlas ofQuaternary deposits, sea bed sediments.bedrock geology and bathymetry in theNOl'\\egian seetor of Skagerrak. NGU Repon96.138.

13. Egersundbanken, Eastern Nonh Sea. Sea bedsediment map. Seale 1:250000. In press.

I~. Mid-Norden. 1'.1Jp of Quaternary deposits. I: 1000 000. Sea areJ compiled by K. Rokoengen.Geol. Survey ofNol'\\'ay. In press.

\5. FolIestad, B. & Ouesen. D.: 1995: Hemne.Quaternary map. Seale \ :50 000. Geol. SUl'\'eyofNol'\\a)'.

•



The BGS lnshore Seabed Characterisation Project

lCES CM 19981E:5

The BGS Seabed Characterisation Project is a three year project funded jointly by the BGS and theDepartment of the Environment, Transport and the Regions (DETR), which aims to collategeoscientific data from the inshore zone (out to 20km) of southem and eastem England to assistdredging Iicence applications within the zone. To date most of the coast from Portland Bill toFlamborough Head has been completed and the joint project finishes in September 1998.

The project has collated data on bathymetry, seabed sediments, bedforms, Holocene sedimentthickness, sediment transport indicators, rates of coastal change and other relevant data. The data havebeen prepared using Intergraph Microsoft as aseries of digital map files, any ofwhich can be overlainon each other, and paper maps produced at any scale. The results give the best available geologicaloverview on the inshore zone of the sectors. The results can be translated to provide the most detailedregional habitats maps of this inshore zone presently available, and systematic overviews of theirsediment transport regimes. However, the scale of the data have not been adequate, neither have thedata been available to consider in detail sediment exchange between the coast and inshore zone.

The digital data (copied only to DETR) carry substantial copyright costs imposed by the dataproviders, and these will limit wider dissemination ofthe data in digital format. However, areport willbe circulated widely but can only highlight a fraction of the digital data, and does not allowmanipulation of the digital data sets. It is hoped to continue the work beyond September to extend thestudied sectors to cover most of the English inshore zone marine aggregate areas of interest.

NERC Land-Ocean Interaction Study (LOIS)

The British Geological Survey's participation in the Natural Environment Research Council's LandOcean Interaction Study has led to the collection ofnearshore data in a broad belt offthe English NorthSea coast, from Berwick-on-Tweed to Great Yarmouth, and extending out to the median line.Although most data have been collected from the coastal zone, some new data were collected furtheroffshore to investigate the thickness and morphology of Holocene sediments. Two localised seismicsurveys were undertaken, in addition to a drilling programme which led to approximately 120 coresbeing recovered from sites above deeps and on sand banks. Figure 4.6 summaries recent marinemapping and data collection work undertaken on the above studies by BGS.

lCES- WGEXT 19 April 1998

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5 REVIEW OF APPROACH ES TO ENVIRONMENTAL IMPACT ASSESSMENT ANDRELATED ENVIRONMENTAL RESEARCH

5.1 ßelgium

Tbe Ministry ofEconomical Affairs, commissioned a geomorphological and sedimentological researchprogramme (Wes/bank), which started in 1990. So far bathymetrical measures (single beam), side scansonar and sedimentological sampling (Van Veen) have been done. Tbe programme is currently in itsthird phase.

Recent developments in shallow water multibeam echosounder techniques have lead to the purchase ofsuch a system, to be installed on the RV Belgiea in 1998. Tbe Belgiea will, for this purpose, beequipped with a center-weil and a mobile transducer.

5.2 Denmark

In Denmark the National Forest and Nature Agency is responsible for administration of marineaggregate dredging. All new licensed areas are subject to a Government View Procedure includingpublic and private involvement.

Recent Environmental Impact Studies

Oresund Link

In the Sound between Denmark and Sweden impact assessments have being carried out prior to theinitiation of the tunnel and bridge project. Tbe consequences of dredging in till and chalk have beenparticularly studied in detail.

In order to assess the environmental impact, monitoring programmes have been established by thecontractor, the Owner (Oresundskonsortiet) and the environmental authorities. Tbe monitoringprogrammes are expected to be the most comprehensive and detailed in the world so far. Tbeprogrammes include monitoring of sediment spreading and sedimentation, water quality, eelgrass,algae, benthos, migrating fish (herrings), birds and coastal morphology.

A status report ofthe condition ofthe environment is published biannually by the Danish and Swedishauthorities.

Tbe management ofthe dredging operations is based on a feed back monitoring programme ron by theOwner. The programme is based on modelling and mapping of sediment spreading and a newlydeveloped eelgrass growth model. Until now only minor effects have been demonstrated. Tbe effectsare in accordance with the forecasts and within the accepted limits. Sediment spill during dredging inglacial till and limestone with a large dipper dredger was about 4 % in average. Tbe spill from backhoedredger is presently 4 - 6 % and the spill from cutter suction dredging 4.5 % in average. Until now,where more than 80 % ofthe dredging has been completed. Tbe total spill has been 4.1 %.

A detailed resource assessment and an environmental impact assessment of dredging of sandfill hasbeen carried out on Kriegers Flak in the Baltic by the Oresund Consortium. Tbe assessment has beenprepared in accordance with the EC Directive 85/337.

Preliminary results from the spill monitoring programme on Kriegers Flak indicate that the spill ratesare strongly influenced by the type of dredger being used. Spill rates range from 0.7 % to 4.8 %. Tberelease of fines and nutrients is very low. Bottom fauna has been resampled in the autumn of 1996 and1997. Preliminary results indieate, in accordance with the EIA, that there is no environmental impactbeyond 1000 m ofthe dredging area.


,'farine Habitat Committee

Research Projects

lCES CM 19981E:5

In 1994 The Forest and Nature Agency initiated a 3 year research project on the consequences ofmarine dredging in co-operation with the Geological Survey of Denmark and the National Environmental Research Institute. The project includes studies of fines in potential resources, computer modelsfor studies of sediment spreading, development of ecological models and field tests. One ofthe aims ofthe project is to establish adecision framework (computer aided Expert System) to evaluate theenvironmental consequences of existing and future dredging projects based on content of fines in theresource, hydrography, spreading offines and ecological models.

Results from analyses of a very large number of sampies from marine resources have shown that thecontent of fmes, Le. silt and clay, only in a few sampIes exceed 5 %. Although the figures are generalthey give a natural framework for the evaluation ofaggregate dredging. Areport has been published in1995 (in Danish).

A detailed study of the ecological consequences of dredging in coarse sediments was started in May1996. The effects on the benthic flora and fauna, on surrounding stone reefs particularly, will beevaluated.

The environmental effects of dredging in gravel deposits have been studied in detail in a highlydynamic area north of Laesoe in Kattegat. Here a dredging operation carried out with a stationarysuction hopper dredger was closely monitored including pre and post video inspection of the sea bedand algae reefs, spill measurements onboard the dredger, current measurements and water sampling.The dredged material was screened onboard, and the initial spill from the dredger was measured tobetween 70 % and 90 %. Most of the spill was sand while only 3 % was in the silt and clay fraction.Spreading of the sediments was modelied with a program developed by the National EnvironmentalResearch Institute (NERI). Most of the spill was sedimented very close to the dredger, where thevegetation was partly buried, and despite the large initial spill, only 5 % was still in suspension 500 mfrom the dredger. This was in accordance with the video inspections where a thin layer of sand wasseen on the leaves ofthe algae at some distance from the dredger. It is expected the sand will be blo"moff during higher currents.

The Forest and Nature Agency and the Coastal Protection Agency have initiated a monitoringprogramme offthe west coast of Jutland to study the effects ofdredging of sand for coastal protection.

The study is based on a comparison with simultaneous changes in a reference area. The post- ,~

nourishment temporal development is analyzed using the BACI concept (B(efore) A(fter) ..C(omparison) I(impact)). A complete quantitative recovery including the number of species, theabundance and the biomass of the bottom has occurred in less than one year after the sand extraction.However, the predominance of a supposed opportunistic species of polychaete (Spio filicornis) in theborrow area may indicate a pioncer recolonization. The impact of sand extraction on the predatorpopulations is limited due to a patchy exploitation pattern leaving plenty of food in 70% of the(undisturbed) bottom and a recovery ofthe benthic biomass in less than one year.

A study of the environmental impact of gravel dredging in the Limfjord area has been carried out bythe Forest and Nature Agency. During dredging the sediments are screened and sand and finer particlesare retumed to the sea. Detailed spill measurements' have shown that the spill rates vary betvveen 60 %and 90 %. Analyses ofthe spill have shown that most ofthe material is sand and less than 5 % consistof silt and clay. The spreading of sediments have been evaluated by the hydrographie model MIKE 21and the spreading module PARTICLE developed by DHI. The tests have shown that despite the largespill rates the spreading of sand is restricted to the dredging area and sedimentation of fines outside thearea is very limitcd.

Marine studies - Biology:

Lysegrund, et stenrev iden sydlige deI af Kattegat. Algevegetation, august 1990. (Lysegrund, a StoneReef in the Southem Part of Kattegat. Algaes). Skov- og Naturstyrelsen 1991.



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lCES CM 19981E:5

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Stenrev i Storeb.elt (Stone Reefs in the Great Belt). Broen I, Broen 11 og Vengeance Grund, Biologiskeoog geologiske undersogelser. Miljo- og Energiministeriet, Skov- og Naturstyrelsen 1994.

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Geologisk og Biologisk kortl.egning af stenrev i Storebreitsregionen. Romso, Lillegrund, Vresen,Tetens Grund. (Geological and Biological Mapping of Stone Reefs in the Great Belt Region,Romso, Lillegrund, Vresen, Tetens Grund). Danmarks Geologiske Undersogelse, Fyns Amtog Skov- og Naturstyrelsen 1995. In press.

Marine Studies - Environmental Impact Assessments.

Norden Andersen, O.G., Nielsen, P.E. and Leth, J., 1991: Effects on sea bed, benthic fauna andhydrography of sand dredging in Koge Bay, Denmark. In: Bjornestad, E., Hagerman, L. andJensen, K. (eds.), Proceedings ofthe 12th Baltic Marine Biologists Symposium, 1991.

Sandsugning og det fysiske miljo - Konsekvenser afrastofindvinding pA havbunden. (Dredging and thePhysical Environment - Consequences of dredging in the Seabed). Kobenhavns Universitet.Skov- og Naturstyrelsen 1991

MiljopAvirkninger ved ral- og sandsugning. (Environmental Impacts from Sand- and GravelDredging). Et Iitteraturstudie om de biologiske effekter afrastofindvinding i havet. DanmarksMiljoundersogelser and Skov- og Naturstyrelsen 1993.

Sammenstilling af eksisterende oplysninger om sedimentspild i Storebreit og Oresund. (Compilation ofexisting information on sediment spill i The Great Belt and Oresund). Mineral DevelopmentInternational. Skov- og Naturstyrelsen 1993.

Sandindvinding pA Kriegers Flak. Vurdering af virkninger pa miljoet (VVM) (Dredging of sand onKriegers Flak. Environmental Impact Assessment). Oresundskonsortiet, Februar 1995.

Nielsen, P.E., 1995: Sedimentspredning og sedimentation i forbindelse med anlregsarbejder pahavomrAdet (Spreading and Sedimentation of Sediments from Dredging Operations at Sea). I:Olsson, I. and Bay, J. (eds.), Strategier für fiskeribiologiska undersökninger relaterede tillbyggfürtag i vatten. TemaNord 1995:513, Nordiska Ministerrädet, Köpenhamn 1995.

Nielsen, P.E., 1995: Spildmälinger i Nissum Bredning (Spill measurements in Nissum Ilredning).Proveindsamling og analyseresultater. National Forest and Nature Agency 1995.

Nielsen, P.E., 1996: SpildmAlinger ved Lreso Trindel, (Spill measurements on Lreso Trindel),Proveindsamling og analyseresuitater. National Forest and Nature Agency, Dec. 1996.

Oresundskonsortiet, 1997: Investigation ofthe Impacts on the marine Environment Caused by a FixedLink across the 0resund. Sand Extraction at Kriegers Flak in 1996 and the Impact on theBenthic Fauna. Technical Report, Oresundskonsortiet, 1997.

Nielsen, P.E., 1997: Sediment Spill and Sedimentation in connection with Dredging and ConstructionWork in Marine Environments. Report submitted to the ICES Working Group on the Effectsof Extraction ofMarine Sediments on the Marine Ecosystem, Copenhagen 1997.

DCA &VKI (1997). RIACON Risk Analysis ofCoastal Nourishment Techniques. The Danish CoastalAuthority in cooperation with The VKI.

Oresundskonsortiet, 1998: Investigation ofthe Impacts on the marine Environment Caused by a FixedLink across the Oresund. Sand Extraction at Kriegers Flak in 1997 and the Impact on theIlenthic Fauna. Technical Report, Oresundskonsortiet, 1998.


Marine Habitat Commiltee

5.3 France

ICES CM I9981E:5

In Dieppe, the biological monitoring of recolonization initiated in 1996 was continued in 1997 in theformer dredging site where extraction activity stopped end 1994. This survey confirmed the results of1996 showing that the impact of sands deposited from overflow can be as high as the impact ofdredging itself on benthic macrofauna. It also confirmed the recolonization process observed in 1996(Annex V ofthe 1997 Report):-

• specific richness is similar between recolonization and reference areas (respectively 46 and 50species per station);

• abundances have slightly progr~ssed up to 1040 ind.m-2, corresponding to 40 % of the referencevalue; and .

• biomass showed the largest increase, doubling between 1996 and 1997, up to 6 g.m_2, representing

75 % ofthe reference biomass.

These three parameters show the progress in biological recovery of the site. Following rates wereobserved since the end ofdredging activity (Figure 5.1):-

• after 16 months, specific richness has fuHy restored and abundances have more rapidly recoveredthan biomass (respectively 56 % and 35 % ofthe reference values); and

• after 28 months, we observed an opposite evolution, with stabilization of densities (59 %) whilebiomass increased up to 75 % ofthe reference value.

Nature of the recolonizing community is closely Iinked to the kind of substratum with dominance ofepifaunal and sand-dwelling species respectively on the shingles and in the fine sands of the easternsector. The western community is dominated by species characteristic of the coarse sands whieh areinfilling the dredging site under the major influence of tidal currents as confirmed by side scan sonar.This restoration process operating from the west explains the decreasing impact observed from thewestern to the eastern part ofthe former dredging site; four levels ofimpact can be distinguished:

• level 0 : reference sediment and community; restoration achieved in the western sector (dominanceofcoarse sand-dwelling species);

• level I : recolonization nearly achieved in the dredging site; low impact of overflow in thedeposition area;

• level 2 : recolonization in progress (Iower abundances and biomass, dominance of opportunisticepifauna on bare shingles); and

• level 3 : maximal impact (Iowest specific richness-abundance-biomass; dominance of sanddwelling species in the fine sands Iinked to dredging andlor overflow).

10 tO + 16 tO+28months months

ßiomass 16,7 34,8 74,7Abundances 14,3 56,1 58,6Specific richness 37 113 92

5.4 Germany

An ongoing joint research project from the Federal Agency of Nature Conservation (BfN) and theUniversity ofRostock partly funded by the Federal Fundation for the Environment (DBU) is analysingthe efTects of dredging on sensitive species in the Baltic Sea in a case study. The extraction field issituated close to Wustrow (Darß-Zingst-Peninsula) and has been dredged in November 1997. First sidescan images of the dredged area in March 1998 show a concentration of dredging tracks forming a4.5m deep trench in the area with no macrofauna colonizing it so far.

A research project is planned by the ßSH concerned with the processes involved in the natural refillingofdeep pits and large-scale extraction burrows in the North and Baltic Sea including the Wadden Sea.

•



" • <l • "~.' •

lCES CM 1998/E:5

Figure 5.1 Recolonization rates for the three main parameters of the macrobenthic community(Percentages indicate relative values compared with reference areas).

. ,~~ \.' ~ (~'~ ~.

120

100-

80-• % 60-

40-

20-

010

(

10 + 16months

10 + 28months

Specific richness

•

5.5 The Netherlands

Enyironmental Research 1997

Borrow Pits (Punaise PrQject)

In autumn and winter 1996/97 a beach nourishment was executed at the central Dutch coast nearHeemskerk/Wijk aan Zee. For the nourishment the pin-point dredge technique was used. The borrow pitwas located at a waterdepth of 7 m and reached a depth of 19m below the seafloor. After the beachnourishment was completed the pit was filled with sand from deeper water. A morphological monitoringprogramme ofthe pit was carried out during the work (Rakhorst, 1997). Before and after the nourishmentan ecological monitoring programme ofthe benthic fauna was carried out. A survey in January 1997, twodays after the refill of the pit, showed that the mollusc Spisula subtruncata survived dredging andtransfering to the pit. The recolonisation of the pit area, especially by the worm Phyllodoce mucosa, wasimmediate following the refill (Van Dalfsen and Storm, 1998a).

After three months (May 1997) the biomass in the pit area was comparable with that just after the refill,but a change in the contribution ofthe different species occurred. The contribution by Spisula subtruncatadecreased. The contribution by worms increased, altough the contribution of Phyllodoce mucosa wasdrastically decreased, showing that this animal is a really opportunistic one. There was 00 recovery of themolluscs and crustaceans (Van Dalfsen and Storm, 1998b). The last survey was uodertaken in April 1998.

Riacon Pro;ect

The fmal report on the ecological effects of subaqueous sand extraction North of the Island ofTerschelling has been completed (Essink, 1997; Van Dalfsen and Essink, 1997). The report describes theeffects on the benthic fauna or a sand extraction (2.5 x 106 m l

) carried out in 1993 at a water depth ofabout 21m. One pre-extraction survey and two post-extraction surveys were carried out. After one year, a


,Uarine Habitat Committee lCES CM 19981E:5

change in benthic community structure was observed due to a reduction in long-living species andrecolonisation by opportunistic species. After two years the original structure had largely been restored.Nevertheless, adult specimens of longer-living species are rare. The total biomass after two years is stillless than that before extraction. Complete recovery is predicted to take a further few years. A summary ofthe results is presented in Annex IV. To verify this prediction a new project Riacon2 has been formulated.In the frarnework of this project a survey was carried out in September 1997, four years after theextraction. Results on the benthic fauna are expected in July 1998.

A bathymetric survey four years after the extraction shows that the sand pit, which has a depth of about2m, has not been filled by natural processes. Nevertheless, bedforms seem to cross the area as they didbefore the extraction.

Large Scate Pro;ects

Several plans for huge land reclamation projects are being launched in the Netherlands. In 1997 thegovemment decided to study the enlargement ofthe Rotterdam harbour area with 1000 ha industrial areaand 750 ha nature area. This enlargement is located just ofT the coast of the present harbour area. Twoother plans, which are much less certain, are the construction ofan airport on an artificial island at sea and •aland reclamation along the coast between Hoek van Holland and Scheveningen (The Hague). For theseprojects a sand supply is needed of800 x 106m3 and 400 x 106m3 respectively.

The amount of marine sand needed for the new Rotterdam harbour, called Maasvlakte2, area will varybet",een 400 and 600 x 106m3

, depending on the chosen design. This amount is about 25 times the presentyearly extraction of marine sands. Studies are underway to decided where to extract this amount of sandand how to do it. An important issue is the maximum extraction depth. At present it is defined at 2 m dueto fishery concems and to keep the same sediment at the seabed, and to facilitate recolonisation ofbenthiefauna. In the navigational channels the extraction depth is 5 m. A widening of the channels by up to1500m is allowed. With large scale extractions, this policy will lead to very large extraction areas. Studiesare being carried out to compare the eeological and morphological efTects of large seale shallow extractionand smaller seale deep extraction. The results of these studies are expected in 1998.

Deep Pits

In June 1997 the Ministry of Transport, Publie Works and Water Management, Directorate SouthHolland, together with the Rotterdam Municipal Port Management applied for a licence for the extractionof30 x 106 m3 sand out of6 borrow pits which will be refilled with relative clean (LC-DMAF guidelines)dredged material coming out of the harbour of Rotterdam. Initially extraction will begin from 2 borrow •pits. To enlarge the knowledge of borrow pits the execution of the works will be accompanied bymorphological and ecological monitoring. Each borrow pit will have a maximum size of 5 x 106m3 • Themaximum depth will be 10 m below seafloor. One pre extraction survey and a survey after one regularextraction of2 m below sea-floor (due to Regional Extraction Plan for the Dutch Part ofThe North Sea)for a beach nourishment, have been carried out.

Environmentallmpact Assessment

Although for each huge reclamation project an individual Environmental Impact Assessment Study(including the sand extraction) has to be undertaken, the general poliey conceming the extraction ofmarine sediments will be revised. Part of this revision is an EIA on the extraction of coarse sand forindustrial use. This sand occurs only in minor amounts near the seabed, but larger amounts seem to bepresent at greater depths beneath the seabottom.

Extension ofthe Rotterdam harbour area (Maasylakte2)

The Scoping Document, which fonns the official start ofan Environmental Assessment Impact study waspublished in spring 1998.


JUarille Habitat Committee

SheJl Extraction

ICES CM 19981E:5

•

•5.6

5.7

From 1999 onwards new maximum amounts for the extraction of sheJls will be defined. The newextraction policy is based on a Environmental Impact Assessment study that will be finished in 1998.Details on the EIA and the new policy are given in Annex IV ofthis report.

Marine Studies

DWW(1997)Survey on the demand for North Sea sand 1996-2030. Ministry of transport, Public Works and waterManagement, Report W-DWW-97-029, 78 pp. (in Dutch).

Essink, K. (1997)RIACON. Risk analysis of Coastal Nourishment Techniques. Final Evaluation Report. Report RlKZ97.031, National Institute for Coastal and Marine Management IRIKZ, Haren. The Netherlands, 42 pp.

Rakhorst, H.D. (1997)Beachnourishment Heemskerk 1996. Technieal evaluation borrow pit I PUNAISE. Ministry ofTransport,Publie Work and Water Management, Direetorate North-Holland, 51 pp. (in Dutch).

Van Dalfsen, JA. & K. Essink (1997)RIACON. Risk analysis of eoastal nourishment teehniques. National Evaluation Report (TheNetherlands). Report RlKZ-97.022, National Institute for Coastal and Marine Management IRIKZ, Haren.The Netherlands, 98 pp.

Van Dalfsen, lA. & B. Storm (1998a)EfTeets on benthic fauna of the use of a borrow pit in the eoastal zone ofT Heemskerk. PUNAISE2; Tlsurvey,january 1997. Report 98-07, Koeman en Bükerk bv, Haren, The ntherlands, 18 pp. (in Dutch)

Van Dalfsen, J.A. & B. Storm (1998b)EfTeets on benthic fauna of the use of a borrow pit in the eoastal zone ofT Heemskerk. PUNAISE2; TIsurvey, May 1997. Koeman en Bijkerk bv, Haren, The Netherlands, 18 pp. (in Duteh)

Norway

No new information

Poland

No new information

5.8 Sweden

The efTeets of suspended sediments on eod eggs and larvae have been studied in laboratory work bythe Swedish National Fishery Agency. Studies have also been earried out eonceming the behaviour ofadult herring and eod when afTeeted by the sediment eloud during dredging. In general the avoidaneeto day and ehalk suspension increases with the sediment load. The mortality studies show that thelarvae are more sensitive to suspended particles than eggs. The studies also showed that thesedimentation rate of the eggs increased due to sediment eoating on the eggs. These studies havealready been reported to ICES (CM 19961E:26).

5.9 United Kingdom

Research

(a) Seabed Sediment Mobility Study - South West Isle ofWight

lCES - JJ'GEXT 27 April 1998


This 18 month project started in November 1996. The contract was awarded to Hydraulies ResearchWallingford and the British Geological Survey, and is managed by Construction 1ndustry Research andInformation Association (CIRIA). Funding was from a wide range of organisations. The aim is toinvestigate sediment transportation pathways and sediment movement in this important dredging area.

The first stage ofthe study was a review ofthe existing knowledge ofthe area. This was then appliedto produce a synthesis ofthe sediment transport regime in the region.

Tbe second stage was the use of numerieal modelling to predict the effects of dredging on the area.Tbe model was built up after a review of existing methods and detailed consideration of issues toinclude when seeking to prediet the effects of dredging in the area. Responses from the earlierconsultation exercise were taken into account in this stage.

In the third stage the numerical model was applied to two hypothetieal dredging areas to evaluate theeffects of extraction on transfer of sediment from the seabed and adjacent coast. Areport summarisingthe findings and making recommendations for improving knowledge of the study area and factors toconsider when assessing future dredging applications wiII be published in May 1998.

(b) Recovery ofthe Seabed (to be renamed Cumulative Impact Study)

Tbis was a jointly funded project by the Crown Estate and MAFF looking at the recovery of anexperimental dredging plot off North Norfolk. Fish populations in the vicinity of the area weresampled and their feeding preferences determined through analysis of stornach contents. Tbeinformation can be used to assess how commercial dredging affects the seabed food resource indifferent areas and whether these effects change with the season. Plume dispersion was also examined.

It is now more than five years since the dredging ofthe experimental site offNorth Norfolk. Tbe latestsampies analysed (3 years post-dredging) show that the area has fully recovered both in terms of thestability of the sediment and range of species although numbers of animals are still somewhat lowerthan the adjacent control areas.

A further 4-year study, whieh commenced in January 1998 is being funded by the Crown Estate andMAFF to investigate the potential for cumulative effects of multiple dredging activity on the seabedenvironment and fisheries. Tbis study wiII initially concentrate on establishing the scope forcumulative environmental effects of dredging activity in licensed areas off Lowestoft and the Isle ofWight. Future work will involve establishing a programme for scientific sampling of the environmentand biota within an area encompassing the totality of actual or potential concems regarding thecumulative effects Le. to include "near field" and "far field" locations. Tbis sampling programme wiIIinclude an investigation of the feeding links benveen the benthos and fishlshellfish populations. Tberewill also be an extension of the regional assessment of gravel communities and documentation ofscales of sensitivity in relation to future dredging activity. Tbis has provided the opportunity tocontinue the monitoring ofthe experimental dredge site from the previous research project.

(c) Seabed Habitat Mapping - BMP - Broadscale Mapping Project

Tbe BioMar team at the University of Newcastle has developed a technique using acoustic signals(RoxAnn) for mapping habitats on the seabed. Tbe acoustic signals reflected from the seabed areanalysed using specially developed software packages. Tbe results can be displayed in real time onboard the survey vessel or with more sophistieated analysis in the laboratory to produce maps oroverlays on existing charts. It is then relatively straightforward to relate the habitats to seabed featuressuch as wrecks, reefs, banks, pipelines, cables etc. and areas whieh are subject to disruption e.g.dredging, beam trawling, drilling, discharges etc.

Tbe DioMar project epitomises the holistic approach now taken to marine environmental studies. TbeConservation Agencies want to map the whole of the UK seabed and Continental Shelf very much asthe land is mapped. Tbey need this information for defining SSSI's, MNR's, SAC's etc. as weil asproviding baseline information against which to judge future proposals. This will c1early require large

•

'.



1 .. ~ ..;~. • J'~.

ICES CM 19981E:5

resources and take a lang time. By taking a joint approach, extra resources can be made available tocomplete the whole picture whilst focusing on areas of special interest or sensitivity to particulargroups. It wiII also have the major benefits of ensuring consistency of approach and comparability ofresults.

Unlike many of the other techniques for surveying seabed habitats e.g. grab sampIes and divers,acoustic mapping is quick and cost efTective, allowing large areas to be mapped economicaIly.

The Crown Estate are funding a two year project with English Nature, Scottish Natural I1eritage andthe Countryside Council for Wales to work at 3 areas (one in each of England, Wales and Scotland) the Wash & North Norfolk Coast, Pembrokeshire and Firth ofLoran.

Charts of BMP output from the Wash and video footage showing Ross reefs have now been producedand are available on the Crown Estate Website at:

• (d)

www.crownestate.co.uk

Anglian Coastal Authority Group (ACAG) N.E. Regional Study

•

This study looks at the sediment regime out to the 50m depth contour from the Holdemess Coast to theThames Estuary. The first stage designed a database which included at least 4500 published referencesto relevant research plus unpublished but verified survey results. The results were used to develop aconceptual model of sediment movement in the survey area. Stage two which is due to start this yearwiII develop the model and verify the predictions with field studies. The results wiII help assess theimpact of existing and future marine aggregate extraction on the coastal zone.

(e) Bristol Channel Marine Aggregates: resources and constraints project

This is a major Welsh Office research initiative funded by the Department of the Environment,Transport and the Regions and the Crown Estate. The principle aims ofthe project are:-

• continue to develop understanding ofthe sediment transport regime in the Bristol Channel, and theextent to which the sediment deposits are interlinked;

• define the marine aggregate resources and to evaluate constraints on their extraction in the BristolChannel;

• prepare areport on the above to assist those organisations involved in the Govemment ViewProcedure (and any subsequent arrangements) in the evaluation ofproposals for future dredging.

Work commenced on Ist September 1996. The project is scheduled to finish in February 1999.

Work carried out to date includes a major consultation and data collection exercise includingcontacting 224 groups and organisations.

Further work is currently underway to determine Iinkages between dredging, sediment transport,deposition and changes to the coastline.

The final report is due to be published in January 1999.

(0 Seabed Characterisation

This project aims to bring into a common format as wide a range of geoscientific data as possible fromwithin the inshore zone (up to 20 km offshore) of England and Wales, and to present such data in away that wiII assist understanding of the modem hydraulic processes controlling sedimentation, thegeometry and Iithology of seabed sediments, and the bedrock geology of the zone. A range of wider

ICES- WGEXT 29 Apri/1998


environmental data are also included. A considerable amount of new information on sedimenttransport has been obtained from detailed sidescan interpretation.

The project is being carried out by the Coastal Geology Group of BGS and it started in late 1995 withcompletion by early 1999. The research is looking at six sectors off the coast of England and Wales,concentrating on those areas most affected by mineral extraction.

Work on the first two sectors Shoreham-Dungeness, and Flamborough Head to Gibraltar Point arecomplete, while work on the third sector (North Norfolk) is advanced. It has been agreed that thefourth sector would cover the area between Winterton and Harwich on the East coast.

Using the second sector as an example, the research has collated data on the following topics:-

Onshore Geology;Offshore pre-quatemary geology;Bathymetry;Offshore quatemary sediments;Seabed sediments;Seabed Morphology and bedforms;Sediment transport regime;Littoral Cells;Coastal morphology and littoral sediments;Tidal information;Sea level change;MAFF sediment and chemical data;Sites of special scientific interest;Offshore hazards;Aggregate industry interest;Hydrocarbon interest;CIRIA report on beach recharge materials; andQuatemary sediment volumes.

The results are digitised using the Microstation Intergraph digital cartographic system. Data werestored in 31 files, which were then transferred onto Microstation Review. The files may be viewed onscreen individually or in combination.

•

lCES-WGEXT 30 Apri/1998

J'farine Habitat Committee ICES CM 1998/E:5

6 REVIEW OF DEVELOPMENTS IN NATIONALADMINISTRATIVE FRAMEWORKS AND PROCEDURES

AUTHORISATION AND

6.1 Belgium

No new infonnation to report.

6.2 Denmark

Legislation and administration.

The Forest and Nature Agency is, according to the Raw Materials Act, responsible for theadministration ofmarine aggregate extraction in territorial waters and on the continental shelf.

A new Raw Materials Act entered into force on Ist January 1997 (Ministerial Order No. 1007 ofNovember 1996). From this date all dredging activities will take place in pennitted areas (Figure 6.1).A 10 year transitional period is allowed for dredging in existing areas.

•

Figure 6.1

g

Dredging areas in Danish Waters, January 1998

New dredging areas are subject to a Govemment View procedure including public and privateinvolvement. The applicant is requested to provide sufficient documentation about volume and qualityof the resources in the area and to carry out an environmental impact assessment (Ministerial OrderNo. 1167 of 16. December 1996). Pennits will be granted for aperiod ofup to 10 years.

Extraction activities which can be assumed to have a significant impact on the environment may begranted only on the basis of an assessment of the environmental consequences in accordance with theEC-directive 85/337. The procedure is laid down in Consolidation Act No. 1166 of 16. December



1996. Dredging ofmore than I x 106 m3 for a specific project or in a single area will always be subjectto this procedure.

Besides permits for dredging in specific areas dredgers must have an authorisation to dredge in DanishWaters. In order to maintain a sustainable and environmentally justifiable dredging activity the totaltonnage ofthe dredging fleet will be held at the present level.

The National Forest and Nature Agency is responsible for the mapping of sand and gravel in DanishWaters. Since 1990 the Geological Survey of Denmark and Greenland (GEUS) has carried out themapping projects.

Marine Management Publications:

Nielsen, P.E., 1995: Marine Resource Management, Geological Mapping and Resource Assessment.In: Mojski, J.E. (Ed.) Proceedings from the Third Marine Geological Conference, The Baltic. PracePanstwowego Instytutu Geologicznego CXLIX, Warszawa 1995, pp. 9-14.

Evaluation ofmarine sand and gravel resources. National Forest and Nature Agency and GEUS, 1997. •

6.3 France

A new law has been adopted following the work of the Working Group managed by the GeneralSecretary of the Sea (membership comprising the Ministry of Industry, Ministry of the Environment,IFREMER, Public Works Administration, and Fisheries Administration). The new law was publishedin November 1997, the principal elements being:

• calcareous and siliceous aggregates are now covered by the same regulation;• the law also applies to French overseas territories.

Subsidiary texts are presently under consideration to determine the precise application ofthe law.

6.4 The Netherlands

6.5

Due to the new Extraction Law (01-01-1997) the applicant has to pay fees for the administrative costs ofthe licence procedure.

United kingdom

Applications to extract marine material remain subject to the non-statutory Govemment Viewprocedure. Which includes studies by Hydraulics Research to determine the effect dredging activitywould have on the adjacent coastline. The statement also identifies any appropriate mitigativemeasure. Any particular requirements are stipulated as conditions to the licence. Applications areaccompanied by a full environmental statement. The Crown Estate will only issue a Iicence followinga favourable Govemment View from the Departrnent of the Environment, Transport and the Regions(DETR) or the Welsh Office as appropriate.

The (at the time) Department of the Environment issued a news release on the 16 November 1995confirming their intention to introduce a statutory procedure for marine aggregate licensing. This willbe based on the Town and Country Planning system. An interim non-statutory system will beintroduced shortly. The statutory procedure requires primary legislation and is awaiting a slot in theparliamentary timetable (1998/99 at the earliest).

•

lCES - WGEXT 32 April 1998

Marine Habitat Commitlee

Management by the Crown Estate

ICES CM 1998/E:5

•

•

Since 1990 the Crown Estate has operated an ArcInfo Geographic Information System (GIS) as theprimary source of data relating to the management of offshore marine aggregate extraction licences.The GIS essentially links graphical information to database tables and contains information ondredging licences, admiralty features, seabed geology, prospecting surveys and a wide range of otherseabed uses and activities offshore. The Crown Estate is currently in the process of replacing theUNIX system with a PC based Windows NT platform which is considerably cheaper, quicker, easier touse and gives a better product.

The GIS is an essential management tool which allows data to be accessed and manipulated to createreports, maps, statistics and charts.

Electronic Monitoring System CEMS)

In January 1993 the Crown Estate introduced an electronic monitoring system (EMS) which recordsthe date, time and position of all dredge-like manoeuvres. All vessels dredging on Crown Estatelicences must be fitted with the EMS which records time and status ofthe vessel at 30 minute intervalson standby or 30 second intervals if indicators show the vessel to be dredging. To ensure securityinformation from the various sensors is encrypted on diskettes which are changed every month. Thediskettes are analysed by the Crown Estate within 20 working days ofthe month end.

In 1997 some 36,000 hours of dredging records were analysed with less than 0.01% of the total hoursdredged being out of area, in all cases licensees provided adequate explanations.

The Crown Estate has provided information on both the GIS and EMS to various groups and has,where appropriate, made detailed information available.



7 CO-OPERATIVE RESEARCH REPORT

ICES CM 1998/E:5

Work continued with the final revisions to the main chapters ofthe Co-operative Research Report witheach editorial group agreeing the final wording to these. A dran of the conclusions/recommendationswas produced and consolidated, with the agreement that the final text of this section would be.circulated electronically to all contributors within one week ofthe meeting (Action: Rapporteur).

8 REVIEW OF INFORMATION ON THE ßALTIC ECOSYSTEM

The Working Group reviewed its Review of the Effects of Extraction of Marine Sand and Gravel onthe Baltic Ecosystem (ACME 1997 Report, reproduced in Annex V) and examined the followingreports received in the light of its review including:

I. Letter from Dr S R Carlberg (Chairman ACME) thanking the Working Group for its 1997 reportof extraction in the Baltic (Annex V).

2. Background document submitted by Germany to HELCOM EC NATURE (revised version, March •1998) entitled Marine Sediment Extraction in the Baltic Sea (Annex V).

3. Dran HELCOl\t recommendation, "Marine Sediment Extraction in the Baltic Sea Area" - adopted26 March 1998 as Recommendation 19/1.

4. Information supplied by ICES Secretariat (Ref C.8r of 26 February 1998) noting that Denmarkwill consolidate the ICES report, and material submitted to EC NATURE by Germany andDenmark for consideration by EC NATURE 8/98 and inviting EC NATURE to consider a jointmeeting with the ICES Working Group on the Effects of Extraction of Marine Sediments on theMarine Ecosystem in 1999 (Annex V).

The Working Group noted additional data on Baltic Sea extraction operations and included these in theannual report and in the final dran of the forthcoming Co-operative Research Report. There was aview that new information did not alter the general conclusions drawn in the 1997 Working Groupreview presented by ACME (Annex V), and that a more thorough review would benefit from theparticipation of EC NATURE in a joint meeting.

The Working Group also noted that, inter aUa, the guidelines on Environmental Impact Assessmentand on survey methods for environmental monitoring (to be published in the forthcoming Co-operativeResearch Report) may be of value to EC NATURE in the work it was undertaking on this matter.

The Working Group expressed the desire to continue the exchange of information on this matter and •hoped that this would ensure that any work and recommendations were complimentary. Specificcomments on the Background Document (Item 2) above were passed to the author.

9 NEW TECHNOLOGY FOR HIGH RESOLUTION SEAßED CHARACTERISATION

Towards the close of the meeting abrief presentation on UK work examining relationships betweenphysical characteristics ofthe seabed and benthic fauna was given. Time precluded a fuller account ofthis high resolution side scan sonar investigation but a written account was presented to the WorkingGroup and is included as a paper in Annex IV. Similar work being undertaken in Canada will bepresented at the 1999 meeting of the Working Group but all Working Group members expressed astrong desire to be kept fully informed ofnew developments/research in this important field.

10 RECOMMENDATIONSIDRAFT TERMS OF REFERENCE

Tbe Working Group on the Effects of Extraction of Marine Sediments on the Marine Ecosystem(WGEXT) should meet 20-24 April 1999 (recommended Chairman Dr Jonathan Side, UK) at one ofthe following Baltic Sea locations:



.<' '11-: . .lo; .J'

ICES CM 19981E:5

If ICES and HELCOM EC NATURE approve an overlapping joint meeting of the Working Groupwith HELCOM EC NATURE, the Working Group should meet at Island of Vilm, Rügen, Germany(BfN-INA); " .~ .. :

Alternatively, if such a overlapping meeting should not prove possible, at Uppsala, Sweden (SGU).

The Working Group will:-

a) collect further information on the effects of extraction of marine sand and gravel on the BalticEcosystem with a view to finalising the Working Group's assessments (1997 Annual Report,ICES CM 19971E:4) and, if a joint meeting is approved, conc1uding areport jointly with ECNATURE.

b) review and report on studies and theoretical work on the effects of aggregate extraction onhigher trophic levels in particular fishes and fisheries.

• c) review and report on the results of environmental research on the effects of turbidity causedby dredging or large scale natural erosion, reviewing also studies of overflow processes,particularly on the measurement and modelling of suspended fines;

•

d) review and report on developments in new technology for high resolution seabedcharacterisation such as micro- and macro-topography, complex sediment distribution andprocess interpretation (essential for sustainable development ofresources and the definition ofhabitats in the coastal zone).

e) review and report on the status ofmarine sediment extraction (in relation to 'use' categories),the development of seabed resource mapping, and developments in the international andnational legal and administrative frameworks and procedures.

11 CLOSE OF THE MEETING

The Report of the Working Group was agreed by the participants. The Chairman thanked theRapporteur and the staff of The Netherlands Institute of Applied Geoscience (NITG-lNO) for theirassistance during the meeting ofthe Working Group.

The Working Group noted that its reports were now being regularly used by national governments andinternational bodies such as HELCOM EC NATURE, OSPARCOM, and CIRIA as weil as byindividual authors. The Chairman noted an increase in requests for information on the WorkingGroup's activities and for the earlier Co-operative Research Report No. 182.

In nominating Dr J Side as the new Chairman of the Working Group, the participants paid a heartfelttribute to Dr S J de Groot for all his efforts and skills during the past 8 years. In particular the WorkingGroup believed that he had been instrumental in ensuring the diverse base of expertise among thescientists and professionals who participated, and in maintaining such a good natured and trulyparticipatory framework for the Group's meetings. In expressing their sincerest thanks the participantswere unanimously of the view that Dr S J de Groot must make all efforts to continue his participationand involvement in all of the Working Group's activities. The Rapporteur was urged to include awritten tribute in the Annual Report acknowledging the major contribution made by Dr S J de Groot tothe work ofthe Group and ofICES.

The meeting was formally c10sed by the Chairman.


ANNEX I

AGENDA

ICES WG on tbe Effects of tbe Extraction of Marine Sediments on tbe Marine Ecosystem

21-24 April 1998, Haarlern, Tbe Netberlands

1. Welcome by representative ofNITG-TNO

2. Welcome by Chairman

3. Appointment of Rapporteur

4. Terms of Reference (see ICES Res. 1997/2.22)

5. Adoption of Agenda

6. Short introduction and explanation by national representatives ofthe routine information as collected atearlier meetings on the status of marine sediment extraction, new legal and administrative frameworksand procedures, the development of seabed resource mapping and environmental research particularlyin relation to the effects ofturbidity caused by dredging or large scale natural erosion. (Information tobe supplied on disk)

•7. Finalise the ICES Cooperative Research Report, including the conclusions/recommendations and

review the final revisions of all sections.

8. Collect further information on the effects of extraction of marine sand and gravel on the Balticecosystem, including the extent and volume of such extractions, and known impacts on, eg benthos,diving seabirds and bottom spawning fish and invertebrates with the understanding that a combinedmeeting will take place with HELCOM EC NATURE in 1999.

9. Review and report on developments in new technology for high resolution seahed characterisation

10. Recommendations

11. Date and place ofnext meeting

12. Close ofmeeting •


•

ANNEX 11

TERMS OF REFERENCE

The terms of reference of the Working Group on the Effects of Extraction of Marine Sediments on theMarine Ecosystem [WGEXT] (Chairman: Dr S J de Groot) were set out by ICES Council Resolution (C. Res199712.22):

a) fmalize the Conc1usionslRecommendations ofthe ICES Cooperative Report (see ICES CM 1997/E:4),and review the final revisions of all other sections (to be available at the beginning of June 1997);

b) collect further information on the effects of extraction of marine sand and gravel on the Balticecosystem, inc1uding the extent and volume of such extractions, and known impacts on, e.g., benthos,diving seabirds and bottom-spawning fish and invertebrates with the understanding that a combinedmeeting of WGEXT members with members from HELCOM EC NATURE will take place in one ofthe Baltic countries in 1999;

c) review and report on developments in new technology for high resolution seabed characterization suchas micro- and macro-topography, complex sediment distribution and process interpretation (thesedevelopments provide the essential data for sustainable development of resources and the definition ofhabitats in the coastal zone);

d) review and report on the results of environmental research on the effects of turbidity caused bydredging or large-scale natural erosion;

e) review and report on the status ofmarine sediment extraction activities (in relation to 'use' categories),the development of seabed resource mapping, and developments in legal and administrative frameworkand procedures.

The Working Group will report to the ACME before its June 1998 meeting and the Marine HabitatCommittee at the 1998 ASC.

* WGEXT members are invited to take the opportunity to discuss and appraise three proposed extractionprojects (each about 800 x 106 m3 ofsand) in the Dutch Coastal Zone and to meet with representatives oftheregulatory authorities and dredging companies on 20 April 1998.


ANNEX III

LIST OF CONTRIBUTORS TO TUE 1998 REPORT

..

NAME

Dr. Claude Augris

Ms. Siän Boyd

Dr. Ingemar Cato

Mr. Jan A. van Dalfsen

Dr. Michel Desprez

lCES-WGEXT

ADDRESS

IFREMERDepart Geoscienees MarinesBP7029280 PlouzaneFRANCE

CEFAS Bumham LaboratoryBumham-on-CrouehESSEXCM08HAUK

TEL + 44 1621 782000 (ext 245)FAX + 441621 784989E-MAIL [email protected]

Geological Survey of SwedenDivision ofMarine GeologyBox 670S-751 28 UppsalaSWEDEN

TEL + 46 181 79188FAX + 46 181 79420/179210E-MAIL [email protected]

National Institute for Coastal and MarineManagement/RIKZPO Box 207NL-9750 AE HarenTHE NETHERLANDS

TEL + 31 505331348FAX + 3I 505340772E-MAIL [email protected]

GEMELStn d'Etudes en Baie de SommeI 15, Quai Jeanne d'Are80230 St Valery-s/SommeFRANCE

TEL + 33 322 26 85 25FAX + 33322268774E-MAIL [email protected]

38 April 1998

•

•

Mr. Chris Dijkshoom RWS-DNZPO Box 58072280 HV RijswijkTHE NETHERLANDSTEL + 31 703366642FAX + 31 703900691E-MAIL [email protected]

Dr. Karel Essink National Institute for Coastal and MarineManagementJRIKZPO Box 30NL-9750 AE HarenTHE NETHERLANDS

TEL +31 505331373FAX +31 505340772E-MAIL [email protected]

• Dr. Gordon Fader Geo.Surv. ofCanada (Atlantic)(by correspondence) Bedford Institute of Oceanography

Box 1006Dartmouth N.S.CANADA B2Y 4A2

TEL + 9024262159FAX + 902 426 4104EMAIL [email protected]

Dr. Bas de Groot Netherlands Institute for Fisheries(Chainnan) Research (RIVO-DLO)

PO Box 68NL - 1970 AB IJmuidenTHE NETHERLANDS

TEL + 31 255 5 64731

• FAX + 31255564644

Mr. Stig Helmig Marine- and Raw Material DivisionNational Forest & Nature AgencyHaraldsgade 53DK-2100 K0benhavn 0DENMARK

TEL + 4539472000FAX + 45 39279899E-MAIL [email protected]

Mr. ChristofHerrmann Agency for Environment and NatureMecklenburg-VorpommemNature Conservation DepartmentWampener Str.D-17498 NeuenkirchenGERMANY

TEL + 49-3834791240FAX + 49-3834899658


Mr. Hans HilIewaert Sea Fisheries DepartmentAgricultural Research CentreAnkerstraat 1B-8400 OostendeBELGIUM

TEL + 32 59 320805FAX + 32 59 330629E-MAIL [email protected]://uc2.unicall.be/RVZ/index.htm

Mr. Bemard Humphreys British Geological Survey(with written contributions Keyworthfrom Dave Harrison) Nottingham NG 12 5GG

UK

TEL+441159363100(ext.4192)FAX + 44 1159363460E-MAIL [email protected]

•Or Andrew Kenny ABP Research & Consultancy LtdPathfmder HauseMaritime WaySouthampton SOl43AE

TEL +44 (0) 1703338100\

FAX +44 (0) 1703338040 '""E-MAIL [email protected]

Mr. Jochen Christian Krause BtN-INAInsel Vilm0-18581 Lauterbach/RügenGERMANY

TEL + 4938301 860FAX + 4938301 86125E-MAIL [email protected] •

Or. Heiko Leuchs Bundesanstalt fUr Gewasserkunde(by correspondence) Kaiserin-Augusta-Anlagen 15-17

PO Box 3090-56068 KoblenzGERMANY

TEL + 492611306468FAX + 49 2611306374E-MAIL [email protected]

Or. Anthony Murray Marine EstatesCrown Estate Office16 Carltan Hause TerraceLondonSWIY SAHUK

TEL+441712104322FAX + 44 171 8397847


•

•

Dr. Poul Erik Nielsen

Dr. Dag Ottesen

Mr Richard Pearson

Dr. Ruud SchUttenhelm

Dr. Jonathan Side

ICES-WGEXT

Marine and Raw Material DivisionNational Forest & Nature AgencyHaraldsgade 53DK-2100 K0benhavn 0DENMARK

TEL + 4539472252FAX + 4539279899E-MAIL [email protected]

Geological Survey ofNorwayLeiv Eirikssons vei 39N-7040 TrondheirnNORWAY

TEL + 4773904011FAX + 4773921620E-MAIL [email protected]

ARC Marine Ud(BMAPA)Burnley WharfMarine ParadeSoutharnptonSOI45JFUK

TEL + 44 1703 828200FAX + 44 1703 828248

Neth. Inst. of Applied Geoscience TNOPO Box 157NL-2000 AD HaarlernTHE NETHERLANDS

TEL + 31 23 5300260/331FAX + 31235352184E-MAIL [email protected]

International Centre for Island TechnologyHeriot-Watt UniversityOldAcademyBack RoadStromnessOrkneyKW163AWUK

TEL + 44 1856 850 605FAX + 441856851349E-MAIL [email protected]

41 April 1998

Dr. Tom Simpson

Mr. Ad Stolk

Dr. Szymon Uscinowicz

Dr. Joanna Zachowicz

Dr. Manfred Zeiler

lCES-WGEXT

Department ofthe Environment, Transport and theRegionsZone 4/AlEland HouseBressenden PlaceLondonSWIE5DUUK

TEL+441718903868FAX + 44 171 8903859

RWS-DNZP.O. Box 58072280 HV RijswijkTHE NETHERLANDS

TEL + 31 70 3366787FAX + 31 703900691E-MAIL [email protected]

Polish Geologial InstituteBranch of Marine GeologySt. Polna 6281-740 SopotPOLAND

TEL + 4858512387FAX + 4858512387

Polish Geological InstituteBranch of Marine GeologySt.Polna 6281-740 SopotPOLAND

TEL + 48585512387FAX + 48585512387

Bundesamt fiir Seeschiffahrt und HydrographieBemhard-Nocht-Str. 78D-20359 HamburgGERMANY

TEL + 49 40 31903282FAX + 49 40 31905000E-MAIL [email protected]

42 April 1998

•

•

ANNEX IV Item 1 van Dalfsen and Essink. The effects on macrozoobenthos of subaquaeous andextraction North ofthe island ofTerschelling, The Netherlands.

•

Working document RIKZ/OS 98.607presented on the ICES Working Group on effects of extraction ofmarine sediments on the marine ecosystem20-25 April 1998, Haarlern, The Netherlands

TUE EFFECTS ON MACROZOOBENTHOS OF SUBAQUEOUS SANDEXTRACTION NORTH OF THE ISLAND OF TERSCHELLING, THE

NETHERLANDS

1.A. van Dalfsen & K. Essink

Ministry ofTransport, Public \Vorks and \Vater Management; National Institute for Coastal and Marine ~lanagementlRIKZ,

P.O. Box 207, 9750 AE Haren. The Netherlands

INTRODUCTION

In The Netherlands the exploitation ofmarine sand deposits in the North Sea has strongly increased since 1990.Marine sand is extracted in the shallow Dutch coastal zone primarily for coastal nourishment. Circa 6 to 7million m3 sand is needed per year to compensate for sand losses in erosive coastal sections ofthe nearshorezone. Recent plans for the development ofartifical islands in the Dutch coastal zone will lead to large scaleextraction ofsand in the North Sea. Volumes ofsand needed are estimated to be I - 2.109 m3.

In the North Sea, only liule information is available on the environmental effects of sand extraction. Benthicorganisms living in or on the top ofthe bottom will be removed by the extraction ofsand. Macrobenthiccommunities ofthe coastal zone play an important role in sea ecosystems, as they provide a food source for fish,shrimps and migrating and wintering diving ducks. To study the response ofthe benthic community to shorefacenourishment and the accompanying subaqueous sand extraction the RIACON program was initiated in 1993.RIACON is co-sponsored by the l\1AST 11 (Marine Science & Technology) program ofthe Commission oftheEuropean Communities and evaluates the ecological risk of shoreface nourishment and subaqueous sandextraction at sites in Denmark, Germany, The Netherlands, Belgium and Spain (Catalonia).

In 1997 the RIACON project was continuated by the Directorate North Sea ofthe Ministry ofTransport, PublicWorks and Water Management to investigate the long-term devellopment ofthe extraction pit and the recoveryofthe benthic community.

METHODOLOGY

The extraction area is situated approximately 8 km north ofTerschelling at a depth between -20 m and -23mDutch ordnance level (NAP)(Fig.l). An amount of circa 2.1 million cubm of sand were extracted from the areabetween May 1993 and November 1993.Following a 'random sampling'- approach, 30-34 stations were selected in 1993 (TO), 1994 (Tl), 1995 (TI) and1997 (T3). At each station one sampie was taken with a Reineck boxcorer (0.078 m2). The macrofauna sampleswere analyzed for density, biomass and species composition.

As initially no reference site was designated, an attempt was made to indicate an area ofreference within theborrow area. By comparing bathymetric maps for changes in depth, the borrow area was divided into twosubareas. .

subarea A (refercnce): +10 to -10 cm depth changesubarea B (disturbed): -10 to -150 cm depth change


RESULTS

GeomorphologyThe bathymetry ofthe extraction area changed considerably as a result ofthe sand extraction. From the TO to theTl survey a lowering of the sea bed occurred of 0.25 m to 1.5 m in an area of circa 1.4 km 2 (Fig. 2: subarea ß).From the Tl survey to the T2 survey a further deepening of circa 0.1 m. was observed in this area. Four yearsafter cessation ofthe extraction the T3 survey still showed a lowering ofthe seabed, with a a bathymetry whichis in size and depth comparable to the bathymetry at the Tl survey. Futhermore, large sand waves can be seen tohave passed though the area without filling in the extraction zone.

BenthosIn subarea ß the abundance ofpolychaetes and crustaceans decreased significantly (Fig. 3). In subarea A a moregradual decline in macrofauna abundance was found from the TO survey to the TI survey. The density ofmolluscs showed little variation from the TO survey to the TI survey. Preliminary results ofthe T3 surveyindicate a futher decline in abundance ofpolychaetes and crustaceans whereas the densities ofmolluscs arecomparable to the TO survey. •In the disturbed area ß the reduction in biomass ofworms and molluscs was significantly found from the TOsurvey to the T2, whereas in the undisturbed area A no significant changes were found (Fig. 4).

The community structure changed as a result ofthe extraction ofsand which is illustrated in the MDS ordination(Fig. 5). The different surveys form three distinctive groups of stations (stress factor is 0.103). The greaterdistance between the stations forming the Tl group in the ordination, indicates a much more heterogenic benthicfauna than was present at the TO survey. In the TI survey the benthic community seems to have shifted in thedirection ofthe TO survey with reduced distances between the stations. No information on the T3 survey is yetavailable.

Increased densities of opportunistic species as Capilella capitala, Spio jilicornis and Spiophanes bombyx werefound in the TI survey.The age composition of Dona'C viI/alus and the Heart-urchin Echinocardium cordalum shifted in the extractedarea (subarea ß) from a population of mostly adults to juveniles (Fig. 6). In subarea A no changes were foundconsidering the age composition. Other species which were rare before the extraction e.g. Spisula sublrzmcataand Tellina lenuis, showed up especially in subarea ß, with high densities ofjuveniles at the Tl survey but werestrongly reduced at the time ofthe TI survey (Fig. 7).

DlSCUSSION

From the bathymetric survey in november 1997 no evidence is found for a filling in of the extraction area,whereas sand waves could be seen to have passed the area. This indicates bottom currents which are sufficientlystrong to prevent sedimentation. Large scale sand extraction in the deeper coastal zone (> 20 m of depth) zonemay therefore result in long-term changes in the seabed morphology. With the extraction of sand the benthicfauna was removed from the dredged track leaving the new sediment layer open to settlement. Species that weremost abundant in the pre-extraction survey (Magellona papillicornis. Nephlys hombergii and Urolhoeposeidonis showed strong reduction in their density in the post-extraction surveys. Opportunistic species, havinglife-history characteristics such as rapid dispersal and high reproduction rates, showed up after the extraction (Tlsurvey) and reached high densities. Molluscs densities increased temporarily because ofsettlement ofrecruitsbut life condition were not favourable to sustain heaIthy populations.Recolonisation processes were clearly demonstrated by the changes in population structure of long living species(molluscs and echinoderms). Adult populations were reduced and recovery ofthese species took place in the Tland TI surveys from settlement ofjuveniles. Recovery of this group takes place primarily through reproductionand most probably not by migration from neighbouring areas. Recolonisation ofthe area by the short-living andmore mobile polychaetes and crustaceans may include both reproduction as weil as migration (Fig. 8).Prelimanary results ofthe T3 survey confirms the futher recovery ofthe long-living species as molluscs andechinodenns.


CONCLUSIONNo evidence for an increased sedimentation or a filling in ofthe area where found, indicating long-term changesof seabed as a result of this type of sediment extraction. The relative shallow sand extraction did not interferewith the natural processes for water and sediment transport in the area. The benthic eommunity strueture at theTI survey deviated from the pre-extraetion situation but showed a recovery towards the pre-extraetion situationat the TZ survey. The effeets ofthe extraction ofsand on the benthic fauna are most evident for the long-livingspeeies as molluscs and echinoderms. Preliminary results four years after the extraction showed no differencesbetween the subareas in total abundance and in the densities ofthe major taxa, vs Mollusca, Crustacea andPolychaeta. Abundances have diviated from the pre-extraction values as a result of natural fluctuations.

LEGEND TO THE FIGURES:

•

•

Figure I.

Figure 2.

Figure 3.

Figure 4.

Figure 5.

Figure 6.

Figure 7.

Figure 8.

Map ofthe Island ofTersehelling and position ofthe areas studied in the RIACON project:borrow area, nourishment area and reference area.

Map ofsedimentation and erosion at the borrow area North off Terschelling betweenFebruary 1993 and May 1994. Two subareas are indieated: A = 'reference area' andB = 'disturbed'.

Mean total abundance (n/m2) of polychaetes (a), erustaceans (b) and molluscs (e) per sampie

in the subareas A and B in March 1993 (TO), Oetober 1994 (TI) and Oetober 1995 (TZ).

Mean biomass (g AFDW m2) ofmolluses (a) and polyehaetes (b) per sampIe in the subareas Aand B in March 1993 (TO), October 1994 (TI) and October 1995 (TI).

MDS ordination ofthe stations ofthe three suceessive sampling surveys (TO, TI, T2) in theextraction area North off Terschelling. Numerical densities were Log(n+ 1)-transformed.Stations ofsubarea A and Bare indieated as 'A' and 'B'.

Abundance of adults and juveniles of Echinocardium eordatum in subarea A and subarea B inMareh 1993 (TO), Getober 1994 (TI) and Getober 1995 (T2).

Abundance of different size c1asses (shelilength) of Spisula subtrzmcata in subarea A (top panels)and subarea B (bottom panels) in March 1993 (TO), October 1994 (Tl) and October 1995 (TI).

Conceptual model of different degree of impact of sand dredging in subarea A (single track)and B (interlinking and crossing tracks) ofthe extraction area, and processes (reproduction,reeruitment, migration) leading to reeolonisation ofthe benthic eommunity.


Map of the Island of Terschelling and position of the areas studied in the RIACONproject: borrow area, nourishment area and reference area. •

North Sea

(l'"~.~.. '

r.0

Wadden Sea

Figure 1.

EXTRACTION SITE MAST·NOURTECFEBAUARY 1993· MAY 1B94

ooo···

oooo..

•~.. I, ,

Sill a-a~":- + + 1118000

0 00 00 0· 0· .· .

dlf'....nc.. in c"' .ft., .xtr1lC1IOn

• • 1 S a 0 • 10 , 0

• • I! 0 • 100 0 ' 0.,

• .. 2. 0 0 .. , so ~., so

• • t S 0 .. 100 • SO 100

• • 100 • SO • ' 00 150

• • SO . ., • ' SO 200

0 . ., • 10 • 200 .. 0

Figure 2. Map of sedimentation and erosion at the borrow area North off Terschelling betweenFebruary 1993 and May 1994. Two subareas are indicated: A = 'reference area' andB = 'disturbed'.


Figure 4. Mean biomass (g AFDW m2) a g/m"

subarea Aof molluscs (al and 10

po(ychaetes (b) per sampie in 8

~• the subareas A and B in oeu

March 1993 (TO), Octoberon 6.:<ö

1994 (Tl) and October 1995 :::E 4(T2).

2 Cl

Q0

Mar.93 OCI.94 OCI.95

b g/m"subarea A

25

~ 20

~ 15

~ ~>-Öa.. 10 Q5

0Mor.93 001.94 OCI.95

a n/m"Ix 10001

Figure 3. Mean total abundance (n/m 2) 12subarea A

of polychaetes (a), 10crustaceans (b) and molluscs ·· 8

S(c) per sampIe in the t 6 gsubareas A and B in March Ci..1993 (TOI, October 1994 4

~(Tl) and October 1995 (T2). 2

0

1.1".93 00t.94 Oet.95

b n/m"

2500subarea A

· 2000·~ 1500~

Ü1000 9500 0 E;3• 0

1.1.,.93 Oet.94 Oet.95

C n/m"

subarea A1500

~ 1000'li:i

500

0c? ~ a

1.1...93 001.94 Oet.95

area 8

~ ~001.94 001.95

barea 8

·~ $et.94 Oet.95

barea B ·.·

Q~

et.94 001.95

barea B

·. ··T TQ g

CI.94 001.95

barea B

8601.94 001.95

April 1998

su

su

su

su

sub

Mor.930

1.1".93

Mor.930

Mor.93 0

471CES-WGEXT

8

October 1994 88

8

B

October 1995 8

8

B

8 A8A

A

8 8

8 8

B B

A

B B

ABA 8

BA B

BA

•Figure 5. MDS ordination of the stations of the three successive sampling surveys (TO, Tl,

T2) in the extraction area North off Terschelling. Numerical densities wereLog(n + 1)-transformed. Stations of subarea A and Bare indicated as 'A' and ' B'.

n/m 2

30

25

20

15

subarea A

Echinocardium cordatum

[J adult 0 juvenile

subarea B •10

5

oMar. 93 Oct.94 Oct.95 Mar.93 Oct.94 Oct.95

Figure 6. Abundance of adults and juveniles of Echinocardium cordatum in subarea A andsubarea B in March 1993 (TO), October 1994 (Tl) and October 1995 (T2).


subarea AIO~9",th r-"":M":'".-rc":'"h"":'":'"9":'"93o---,

20-30

10-20

<10

Octobor 1994 Octobor '995

o 10 20 30 40 n/m' 0 10 20 30 40 n/m' 0 10 20 30 40 n/m'

subarea B

•'on9th ""'--M-.-rc-h-'-9-9-3--,

mm

20-30

Octobor 1994 October '995

Figure 7. Abundance of different size c1asses (shell lengthl of Spisula subtruncata in subareaA (top panels) and subarea B (bottom panels) in March 1993 (TO), October 1994(T1) and October 1995 (T2).

1. Before extr.ction

o 0 ~ 0

2. Directly after extraction

single track

o 0

3. Recovery process

interlinking andcrossing tracks o

O'

Figure 8.

lCES-WGEXT

V reproductionl recruitment

= migration

Conceptual model of different degree of impact of sand dredging in subarea A(single track) and B (interlinking and crossing tracks) of the extraction area, andprocesses (reproduction, recruitment. migration) leading to recolonisation of thebenthic community.

49 April 1998

ANNEX IV Item 2 Nielsen. Monitoring of dredging activities on Kriegers Flak, Baltic Sea.

Monitoring of dredging activities on Kriegers Flak, Baltic Sea

Poul E. NielsenNational Forest und Nature Agency

Summary of Environmental Impact Assessments.

The dredging area Kriegers Flak is used by the 0resundskonsortiet for thedredging of sund fill for the fixed link between Denmark und Sweden. Thearea which is dredged by trailing suction dredgers has un area of6,7 km2

• Thewater depth is 20-22 m.

300.000 m3 was dredged in 1996 und 600.000 m3 in 1997. The spillage was2,7 %. The spill consists mainly ofvery fine sund with a content ofsilt undclay. Environmental impacts are accepted in un impact area of 1 km aroundthe dredging area. Outside this area, no impacts from the dredging activitiesare accepted (reference area).

A baseline investigation ofthe bottom fauna was carried out in 1995 prior tothe commencement ofthe dredging activities. Subsequently the area has beenmonitored in the auturnn of 1996 and 1997.

The Benthic fauna at Kriegers Flak is a denely populated Macomacommunitydominated by a few species ofpolychaetes, bivalves, gastropods und crustaceuns. The structure ofthe benthic community depends on the water depth,the composition ofthe sediment und the occurrence ofthe common mussel(AfytilliS edlllis).

Results from the monitoring programme are shown in figure 1. In 1996 asignificunt decrease in abundunce und biomass was observed in the impactarea mainly due to a decrease in the occurrence ofthe common musse!. Anequivalent decrease was observed in 0resund during 1996.

In 1997 a significunt increase in density und biomass was observed. Investigations in 1996 und 1997 ofthe sediment composition have shown un increase in loss ofignition and silt/clay content since 1995.

The composition ofthe bottom fauna has been uniform in thc impact area asweIl as weIl in the referencc area bcfore (1995) und after (1996 und 1997) thccommencement ofthe dredging.

Detailed unalyses ofthe fauna have shown significunt differences in thecomposition between the impact area und the reference area as weIl as significantly different developments. However these differences are mainlycaused by natural fluctuations in occurrence ofthe dominant species Ce.g.AfytilliS edlllis), and cannot be corrclated to changes in the sediment. No impact on the bottom fauna from sediment spill can be observed. Differencesand changes are natural variations.

'.

•

leES - lrGEXT 50 April 1998

No of species1430 ern-'16

14

12

e-!----,-----r----.--___,1995

Abundance

1996 1997

•* *300ol---,........;~--.-----:~..,....--___,

Biomass

1995 1996 1997

* *2001---,----,,.--...;.;,;,..--,---...,1995 1996 1997

ICES- WGEXT

• lrrpacI 0 Rderen:e

Figure 1. No. ofspecies recorded and total abundance and biomass per m2 inthe Macoma community.

References.

0resundskonsortiet, 1996: Investigation ofthe Impacts on the marine Environment Caused by a Fixed Link across the 0resund. Baseline study ofbenthic fauna at Kriegers Flak. Technica1 Report, 0resundskonsortiet, 1996.

0resundskonsortiet, 1997: Investigation ofthe Impacts on the marine Environment Caused by a Fixed Link across the 0resund. Sand Extraction atKriegers Flak in 1996 and the Impact on the Benthic Fauna. Technica1 Report, 0~esundskonsortiet, 1997.

0resundskonsortiet, 1998: Investigation ofthe Impacts on the marine Environment Caused by a Fixed Link across the 0resund. Sand Extraction at

51 April 1998

ICES-WGEXT

Kriegers Flak in 1997 and the Impact on the Benthic Fauna. Technical Report, 0resundskonsortiet, 1998.

52 April 1998

•

•

ANNEX IV Item 3 Stottrup et a/. Is there a case for artificial reefs in Denmark?

•

Is there a case for artificial reefs in Denmark?

J.G. Stottrup', S.HeImig2, J.K. Petersen 3,C. Krog4, R. Zorn', H.T. Madsen6 and A. Moller7•

'Danish Institute for Marine Research, North Sea Centre, DK-9850 Hirtshals, Denmark.2The National Forest and Nature Agency, Haraldsgade 53, DK-2100 Kbh 0, Denmark.lNational Environmental Research Institute, Frederiksborgvej 399, DK-4000 Roskilde, Denmark.4Association for Fisheries in Denmark, Box 251, DK-6700 Esbjerg, Denmark.'Danish Hydraulic Institute,Agem Alle 5, DK-2970 Horsholm, Denmark.6Danish Coastal Authority, Hojbovej I, DK-7620 Lemvig, Denmark.7AgriContact, Torupvejen 97, DK3390 Hundested, Denmark.

A 2-year project entitIted: "Deployment of artificial reefs for stock enhancment of lobster and theprotection of nursery grounds for marine fish", was initiated May 1 1996, financed through FIUF(Financial Instrument for the Development ofthe Fisheries Sector), 50% ofwhich are EU-funds.The project aimed at reviewing the available literature on artificial reefs, their uses and resultsobtained and evaluating the potential for deployment of artificial reefs in Denmark. This wascompiled in a Danish report completed in 1997 (DFU-rapport nr. 42).

During the course ofthe project special attention was brought to the particular Danish tradition forstone extraction from marine habitats which has been taking place for almost a century. Substantialamount ofhard bottom, stones and boulders have been removed in the shallow coastal zone withwater depths below 10 metres. The extent and impact ofthis activity on the habitat has not beendocwnented, and no action to date has taken place to restore the nature in these regions. Nosystematic research or research programmes have been focused on hard bottom, and no monitoringprogrammes have included hard-bottom fauna, not even during the first 10 years of the national\Vater Quality Plan. The importance ofhard bottom for the marine biodiversity remainsunquestioned, but the ecological significance and the importance for fish stocks and fisherydeserves research priority. There is still a need to develop methods for monitoring hard-bottomfauna and associatied fish populations. On the other hand, the project elucidated the importance of\\Tecks in commercial fishery for cod, a relatively new type of fishery which flourished with thewidespread use ofGPS and which docwnents the attraction offish with resulting high CPUE's forthese accidental artificial reefs.

One ofthe main recommendations from this project was for nature rehabilitation. But this may takeplace along with other considerations, such as the protection of feeding and nursery grounds or ofbiodiversity or it could simultaneously be directed towards enhancement ofa depleted stock, suchas the case for lobster. Knowledge gained from such interdisciplinary research may benefit othercoastal activites such as work with coastal protection or improving the design ofprotection aroundmarine constructions such as bridgepillars and windmill foundations in the marine environment.

ICES- WGEXT 53 ,lpri11998

ANNEX IV Item 4 Stottrup and Stokholm. Deployment of artificial reefs for stock enhancement oflobster and protection ofnursery grounds for marine fish.

.....

Kunstige rev

Review om formal, anvendelse og potentialei danske farvande

Hovedredakt0rer

Josianne G. St0ttrup og Hanna Stokholm

•

Danmarks Fiskeriunders0ge1serMd. far FiskebialogiBox 1019850 Hirtshals

ISBN: 87-88047-50-4

ICES- WGEXT 54

DFU-Rapport nr. 42

April 1998

English Summary

The project: " Deployment of artificial reefs for stock enhancement of lobster and theprotection of nursery grounds for marine fish", was carried out in co-operation with thefollowing partners:

•

Danish Institute for Fisheries Research (DFU) coordinator '

Ministry of Food, Agriculture and Fisheries

National Environmental Research Institute(DMU)

Danish Hydraulic Institute (DHI)

Danish Institute for Fisheries, Technology andAquaculture (DIFTA)

The National Forestry and Nature Agency (S&N)

Association for Fisheries in Denmark (DF)

Danish Coastal Authority (KI)

Agri Contact

Perstrup Beton Industri AlS' .

Josianne St,mrupHanna StokholmNiels-Henrik Norsker

Dan Herrestrup

Jens Kjerulf Petersen

Rene ZornErik Asp Hansen

Svend Steenfeldt

Stig Helmig

Carsten Krog

Holger Toxvig Madsen

Ame M0IIerJ0rgen alsen

ale Fast

This report is a result of the work earried out during phase 1 of a three-phase projeet. Qnly thefirst phase has been funded, finaneed through FIUF (Financial Instrument for theDevelopment ofthe Fisheries Seetor), 50% ofwhich are EU-funds. The report summarises 6individual reviews or reports on various subjects relating to artifieial reefs attaehed asAppendices. The language is Danish.

The airn ofthe projeet is to exarnine the potential for re-establishing, proteeting anddeveloping fisheries resourees in'inner Danish waters through deployrnent of an artifieial reef.Emphasis is on the lobster resourees as weil as eertain eomrnereially important demersal fishspeeies.

The seeondary airns are to:re-establish habitats ~n areas whieh have been disturbed through stone fishing, andregenerate habitats for naturally oeeurring hard-bottom fauna and flora (naturerehabilitation)

establish an environment similar to a natural habitat with maxirnwn density oflobsters in different stages of developrnent on loealities where these habitats are notavailabIe; in other words to enhance lobster stocks

lCES - lrGEXT 55 April 1998

establish an environment which renders proteetion to lobsters at all stages ofdevelopment

increase production (and biomass) ofthe bottom fauna in the target area and thusincrease fish prey

establish good nursery and feeding founds for marine fish (increased preyproduction, good shelter possibility, protection from dragging fishing gear

protect the coast through design and location of an artificial reef (coastal protection).

During phase 1, a literature study was conducted to examine the potential for fulfilling theabove-mentioned aims and whether or not it \vould be desirable in Danish waters. If deemedfeasible the following 2 phases would be put in action pending further funding which first hadto be sought. . •

The results from the literature study are thus summarised.Artificial reefs have been deployed in 29 countries, the heaviest activity being reported inJapan with over 7300 reefs until 1987, constituting a deployed volwne of 17 million m3 at atotal cost of 1.2 billion US$. The aims for deployment of artificial reefs are manyfold.However, the most widespread aim is the increase of fishery resources. Other aims include there-establishment ofthe.natural habitat, resource management and eoastal proteetion.

, ,

A major eontention of artifieial reefs is that they may simply attraet fish rather than eontributeto an ine,rease in production ofthis resouree. However, the catch p~r unit eITort has beendemonstrated to increase at or near natural or artificial reefs. Indeed Danish fishermen havesimilar experiences with \vrecks. This inerease, whatever its origin, has such advantages that itprovides the basis for the extensive Japanese reef poliey.

The deployment of artificial reefs will result in, the establishment of a new habitat with •settlement of larvae and plant spores which otherwise \vould have been lost to the ecosystem.On a stable, natural type of structure the succession of plant and animallife \'~ill resemble thaton natural reefs. Foreign studies on experimental reefs have ShO\'ffi that the physicalheterogeneity and site are the tv:o most important factors determining reeruitment of epifaunaand flora Thus, in designing an artificial reef, individual elements as weIl as the overall reef .strueture should consider the biology, dispersion and life eycles ofthe potential speeies foreolonisation.

Present day reefknowledge is insuffieient to predict effects on fauna, flor~ or fish. Thus thedeployrnent ofan experimental reefshould be aeeompanied by intensive research.on dynamicaspects of sedimentation, recruitment and eolonisation of reef organisms and the effects ofhydrographie and biologieal factors. Results from sueh research is not limited to reef

, management but has implications for nature-restoration policy in marine habitats.

The European lobster is a bottom-dweller, easy to catch, tag and release and the tags can beregistered eleetronically. The generation time is so long that a given stock would require morethan a deeade to re-establish itself naturally. Thus, this species is ideal for stock enhaneement


•

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in Danish waters in combination with an artificial reef. Results from several Europeancountries show that it is possible to enhance lobster stocks through releases of rearedjuveniles. In designing such a programme it is however, recommended that preliminaryresearch on habitat criteria for lobsters is conducted and that released lobsters are tagged tostudy the impact of such releases.

A well-developed reef and wreck fishery with non-dragging gear exists in Denmark.Utilisation of fishery resources on or around a reef will not require new knowledge, change ofattitude or investment in new gear. On the other hand, the catch on \\Tecks or reets is veryeffective and a conflict may arise bet\veen an optimal exploitation and fishery management.Therefore the deployment of an artificiaI reef requires the identification of fishery interestsand their incorporation in the overall fishery management. Socioeconomical analysis shouldbe an integral part ofthe study.

The importance ofhard bottom for the marine biodiversity remains unquestioned. It allowssessile fauna to establish itself and provides stable attachment for algal vegetation. The reefsare important feeding areas for fish and birds and these together \vith macrophyte forestsprovide sheIter for marine fish. In Denmark, stones have been fished for almost a centtu"vremoving a substantial amount ofhard bottom and reefhabitat particularly in the shallowcoastal zone with water depths below 10 metres. Very little information exists on thedistribution and extent of hard bottom or natural reefs in Danish waters and work to map thesewas first initiated in the present decade.

Thus exists the potential for re-establishing hard bottom or reef habitats in a structuredmanner. In' view ofthe on-going extensive terrestrial nature-rehabilitation, a similar activity inthe marine environment should be seriously considered. The mapping'ofthe extent ofhardbottom, the ecological significance and the importance for fish stocks and fishery should gainresearch priority. The deployment of an experimental reef with well-defmed aims willsignificantly contribute to the understanding of reef ecology and the importance of reefs forthe fishery and the environment.

• Existing knowledge from geological and biological research combined with fishermen'sknowledge on good lobster grounds provides the basis for site evaluation for the deploymentof a multi-purpose reef aimed at stock enhancement of lobster resources and naturerehabilitation. The re-establishment ofreefhabitat would increase the ecological andeconomic value of a previously disturbed locality.

It was not the purpose ofthis study to propose detailed locations, shape, size or material for anartificial reef, but these subjects have been discussed during the course ofthe project andseveral criteria have emerged which should be a tangible part of future work in this area.

The site of choice is closely linked with the purpose ofdeployment and is therefore limited toareas where fishing for stones has taken place, where there is a stony or mixed sand-stonebottom and in relatively shallow depths. Close to shore, the shape could be designed to add anextra dimension of coastal protection and in areas which would provide sheIter for juvenilefish or where lobsters occur naturally. Kattegat has been nominated as an area, which fulfillsseveral of these criteria and where the study of an experimental artificiaI reef would bepractically feasible.


The deployment of an experimental artificial reef is recommended. In'stead of simply layingdov.-TI stones in a random fashion, an artificial reef should be constructed to fulfiIl severalpurposes simultaneously:

nature rehabilitationenhancement oflobster stocksprotection of feeding and nursery groundsprotection and increase ofbiodiversity.

Parallel to the above research could be conducted to examine the potential for secondarypurposes such as:

coastal protectionprotection of ship harbour channelsimprove the design of protection around marine constructions such as bridgepillarsand \vindmill foundations to serve as functional artificial reefs.

The project would require an integrated research effort in co-operation between those partners\vith the necessary expertise to produce the scientific evidence for the extent ofwhichartificial reefs fulfill the aims set down. The present group agreed that the foIlo\ving basicelements should be incorporated in such a project.

a well-defined research area large enough for a reference and artificial reef areaan artificial reef area large enough to enable the study of colonisation with andwithout the influence ofthe releases oflobstersthe results should be based on research of minimum 2 years before deployment and 5years post-deployment -:data to be compared with similar data, where available, on natural reefssocioeconomic .studies should be an inherent part of the projectthe fishery utilisation arid value ofthese resources should-be examined andcompared to the value ofv.-Teck fishery and weIl as to the extra costs involved inlaying a specifically designed artificial reefinstead ofrandom laying ofrocks orboulders. -

•

•


ANNEX Lv.. • Jte91 5 Shell Exq-action !.IL12:.NetherMiM5~rieC'6Ib'g4dut!effe't{8tl!Atl.policy development.W erKaOCument~ Directoraat.Generaal Rijkswaterstaat

~ Rijksinstituut voor Kust en Zee/RIKZ

Aan

ICES Working Group on the Effects ofExtraction of

Marine Sediments on the MarineEcosystem (WGEXT)

Meeting 20-24 April, 1998

Haarlem, The Netherlands

• Van

Dr. Karel EssinkDatum

6 April 1998Onderwerp

Shell extractionDoorkiesnummer

+31.50.5331 373

8ijlage(n)

Nummer

RIKZ/OS-98.604xProject

ICES·ICES

She/l Extraetion in The Netherlands:

ecological effeets and policy development

1. INTRODUCTION

Marine shells have been fished in Dutch coasta/ waters (mainly the WaddenSea) since lang. Originally, they were burned to produce Iime. At presentthese shells are being used for various purposes to a total amount of 257.00- 277.00 m3 per year (Table 1). For the coming 10-15 years an acceptedannual demand of 297.00 - 364.000 m3 is foreseen (RWS, 1998a).

The majority of the shells fished consists of cockles (Cerastoderma edule).Spisula spp., Macoma balthica and various other species constitute therest. An non defined proportion consists of fossil shell material from Eemien(Wadden Sea) or even Pliocene and Eocene (SW Netherlands) (OE BRUYNE,1992.)


Table 1. Demand tor shells (1995; m 3) tor various applications in The Netherfands

(trom RWS. 1998a)

ApplicationDrainageFoot- and cydepathsUme in poultry fodder etc.Floor Isolation in housesUmeHelophyte filtersOther, incl exportTotal

Demand (1995)60.000 - 75.00072.00040.00025.0008.0004.000

48.000 - 53.000257.000- 277.000

•In the preparation of new national policy regarding the exploitation of sheHresources two main issues have been considered recently, viz.:

• environmental effects• extraction vs. natural production

2. ENVIRONMENTAl EFFECTS

2.1. Effects on geomorphology

Extraction of shells from deposits in tidal areas such as Wadden Sea, Easternand Western Scheldt, may locally increase erosion of tidal flats margins andenhance the dynamics of tidal gullies and channels. These effects areconsidered to be relatively small-scale by nature.

Extraction of sheHs will also increase the tidal prism of tidal basins. Theextent to which this occurs , e.g. as compared to extraction of sand, is notconsidered to cause real problems. One exception is being made for theEastern Scheldt. a system which since the construction of the storm-surgebarrier still is out of balance as far as sediments are concerned (RWS,1998a).

2.2. Effects on ecology

Extraction of shells may lead to increased turbidity of the water co/umn,especially in case of sheHs embedded in c1ay deposits. This may lead toreduction in phytoplankton primary production, productivity of nearbyeelgrass beds, impairment ofgrowth of filter feeding zoobenthos andreduced foraging possibilities for visual predators such as the Arctic Tern(Sterna sandvicensis).


•

Quantitative information, however, of these ecological effects is notavailabfe.

Disturbance of birds may occur by shell extracting vessels when operationless than ca. 500 m from concentrations of foraging birds at intertidal flats,of from breeding colonies.

Disturbance. of seals «(ommon Seal-Phoca vitulina; Grey Seal-Halichoerusgrypus) may occur by shell extracting vessels when operation /ess than ca.1500 m from haul-out and nursing locations.

Shell deposits on the seabed may serve as deposition area for eggs of gobies(Pomatoschistus minutus, Gobius microps) (FONDS, 1973). There are noindications that egg deposition possibilities are affected by shell extraction ..

3. POLl(Y DEVELOPMENT

3.1. How to manage shell extraction?

One of the tasks of the Ministry for Transport, Pub/ie Works and WaterManagement is to take care of the regular provision of materials such assand, gravel and shells.With respect to shells resource management has to deal with a) fossildeposits, and b) natural production of shell material. Shell extractionexploits both sources (Figure 1).

Extraction

Natural Production

Recent

Fig. 1. Shell extraction in relation to natural shell production and fossil deposits.


3.2. A new policy

Recently, in The Netherlands a new policy has been developed with respectto the extraction of marine shells. In line with the policy of sustainable useof the Wadden Sea as an ecosystem, it is proposed to balance shellextraction with natural shell production. This new policy proposal is now in.the course of following the necessary political and legis/atory procedures.

To obtain a firm fundament for the implementation of this policyestimations were made of the average annual natural shell production inDutch coastal waters. This was done for the cockle (Cerastoderma edule)and for 5pisula spp. Loss factors, e.g. due to cockle fisheries, due to burialat places where extraction will not be possible, and due to fragmentation instomaehs of birds and flatfish were taken into account. For cockle in theWadden Sea • these estimations were based on data sets of ca. 30 year, forother areas and for Spisula, only much shorter data sets were available.

In Table 2 an overview is presented of the obtained estimates of the 'net'natural production of shells in different water systems.

Table 2. Estimated 'net' annual production of shells (m 3) in different Dutch coastal

waters (From: RWS, 1998a.b)

•

2.00078.0005.000

217.000

Water system CocklesWadden Sea 132.000Wadden Sea coastHolland coastVoordelta .Eastern ScheldtWestern ScheldtTotal:

4. REFERENCES.

Spisula

137.000121.000102.00012.000

2.000374.000

OE BRUYNE. R. H., 1992. Onderzoek winbare schelpvoorkomens. RijksGeologische Dienst, Haar/em. Rapport nr. OP6528.

FONDS. M .. 1973. Sand gobies in the Dutch Wadden Sea (Pomatoschistus.Gobiidae, Pisces). Neth. J. Sea Res. 6: 417-478.

RWS. 1998a. Draft-National Poliey for Shell Extraetion (Landelijke NotaSehelpenwinning). Ministry for Transport. Pub/ie Works and WaterManagement. Directorate-General tor Publie Works and Water Management (inprep.) (in Outeh)

RWS. 1998b. Draft-Environmental Impact Study Shell Extraction (Concept MERSchelpenwinning). Ministry tor Transport. Public Works and WaterManagement. Directorate-General for Publie Works and Water Management (inprep.) (in Dutch)

ICES- WGEXT62

April 1998

•

•

ANNEX IV ltem 6 Kenny. A biological and habitat assessment ofthe seabed off Hastings, Southem England.Biological and Habitat Assessment of Hastings Shingle Bank

A BIOLOGICAL AND HABITAT ASSESSMENT OF THE SEA-BED OFFIIASTINGS, SOUTI~ERNENGLAND.

A. J. Kennyl on behalf of the Hastings/Cutiinc Dredging Association

1. INTRODUCTION

In support of an application by the Hastings and Cutline Dredging Association toextend dredging to the south of their existing Iicense on Hastings Shingle Bank, anilssessment of the benthos and associated habitats was undertaken in September 1997(Figure 1). This report provides new infonnation on the present status of thc biologyand habitats found on Hastings Shingle Bank.

Marine won aggregate has been dredged off Hastings Shingle Bank since 1988 andduring this time various monitoring programmes and assessments have beenconducted by both the industry and MAFF. For example, Shelton and Rolfe (1972),and Dickson and Lee (1972) examined the physical and biological characteristics ofthe sea-bed following the excavation ofrelatively large pits by suction hopper dredger.However, it was not until 1986 that a comprehensive assessment of the benthicmacrofauna inhabiting the gravel deposits was carried out by MAFF (Rees, 1987).This study provides valuable baseline data on the status of the macrofauna prior to thestart of dredging.

In 1989 under the tenns and conditions of the old licence, the licensees were pennittedto extract up to 1.5 million tonnes per company, with no time limit. The licence todredge was renewed in 1995 and extended for a further 5 years following a positive'Govemment View'.

Under the terms ofthe existing conditions there are 5 licencees (collectively known asthe Hastings/Cutline Marine Aggregate Dredging Association), namely; ARC MarineUd., Civil and Marine Ud., SCS Co. Ud., East Coast Aggregates Ud. and UnitedMarine Dredging Ud. Each company is allowed to extract up to a maximum of 1million tonnes per annum, but no more than 3 million tonnes over 5 years.

In order to characterise and define the spatial extent of the principal macrobenthiccommunities, a survey of single benthic grab stations was devised to cover both theapplication area and surrounding sea·bed. In addition, the monitoring requirements ofthe assessment were satisfied by sampie replication in five areas to allow both theprimary and potential secondary impacts of dredging to be evaluated.

In recognition of the effects that sea-bed substrata, sediment dynamics and topographymay have on benthic communities, a side-scan sonar survey was conducted toestablish the exact spatial boundaries of the principal benthic habitats. The sonar datawas mosaiced to provide total coverage ofthe sea-bed and its associated habitats.

Additional data on the distribution and type of sediments was provided, er availablefor review, by the HDA. This inc1uded rcsults from a Shipek grab survey to

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Biological and Habitat Assessment ofHastings Shingle Bank

characterise surficial sediments within and adjacent to the extraction site, andgeophysical data co11ected within the proposed extraction site, including highresolution side scan sonar.

2. SURVEY DESIGN AND IMPLEMENTATION

2.1 Benthic Grab Survey

The design of the macrobenthic survey off Hastings was finalised after consultingBritish Geological Survey marine aggregate reports, HR Wallingford dredge plumedispersion models and existing benthic surveys carried out by MAFF since 1986.

Benthic sampies were co11ected from the fishing boat 'Corina' chartered out ofNewhaven on the 18 and 19 September 1997. Vessel navigation was achieved by a'Shipmate' plotter, however position fixing was obtained using a Rockwe11 ZodiacGrS 12 channel receiver and a Scorpio differential beacon receiver to provide positionfixing accuracy to within 20 metres.

A mini-Hamon grab was used for the co11ection of sediment and fauna, and standardoperating proccdures for its usc and subsequent sampie processing on board thesurvey vessel were fo11owed (see below).

In total 53 benthic sampies were co11ected from 32 stations, of which a total of 9 \vereselected for sampie replication. Three grab sampies were taken at each of thereplicated stations. Figure 2 shows the actual location and number of sampiesco11ected.

The mini-Hamon grab was deployed within 100 m range rings placed around eachstation. Onee the grab was on the sea-bed arecord of the position was made beforerecovery of the grab. Upon retricval, the sampie was released in to a 30 litre plasticbin and assessment of sampie quality was made by measuring the volume of sedimentco11ected. In addition, a 500 cc sub-sample was taken for particle size analysis (seebelow).

The macrobenthic sampies were initia11y sorted whilst at sea using a purpose builtbenthos sorting table fitted with a 5 mm square mesh sieve. Animals and sedimentpassing over the 5 mm sieve were subsequently co11ected on a 1 mm square meshsieve and then 'puddled' to remove the finer sediment. The material retained on the5 mm sieve was washed with sea-water, before a11 individual benthic organisms andrepresentative specimens of colonial taxa were removed and fixed in 7 % bufferedformaldehyde solution and stored for later laboratory identification and enumeration.Sampies co11ected at the replicated stations had a11 oftheir colonial fauna removed andfixed prior to laboratory biomass determinations. The sampie fraction retained on the1 mm sieve was retained whole and stored for laboratory analysis.

Laboratory identification of fauna was carricd out by SEAS Ud. in Oban, Scotland, amarine biologicaI consultancy who participate in the National Marine BiologicalAnalytical Quality Contral scheme.


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ßiological and Habitat Assessment ofHastings Shingle Bank

Sediment sub-samples were processed by ETS Ud, and were initially \-'let sieved overa 0.063 mm mesh to, provide an estimate of the 'silt' [raction. The remaining sampIewas then oven dried and sieved through a nest of sieves, conforming with theWentworth scale, from 16 mm to 0.063 mm. The percentage distribution, by weight,of particles for each size fraction was then calculated. It was considered that sedimentretained on a 16 mm sieve generally provides a stable coarse substrata for the benthicfauna and that size c1assification of sediment greater than 16 mm provides !ittleadditional information on the habitat characteristics ofbiological signifieance.

2.2 Side-scan sonar survey

A dual frequency 'GeoAeoustics' side-scan sonar tow fish with a 'GeoAcoustics'transciever surface control unit were used off the hydrographie survey vessel "rUgierRose" on the 14, 15 and 16 September 1997. The track plot ofthe survey is shov..n inFigure 3. The survey was conducted at 100 kHz frequency to provide sufficient swath(200 metres per channel) for thc given Hne spaeing (400 metres) producing 100%coverage of the sea-bed. Data was recorded digitally and 'real-time' post-processedusing a 'MUSE' sonar mosaie \'lork station, to provide a visual mosaie of the sidescan record. Survey speed varied between 2 and 6 knots and slant range eorreetion,water column removal and speed over ground were used to produce a true XY sidescan sonograph image of the sea-bed. The position of the tow fish was logged every20 metres using course-made-good information and manual layback entry to establishabsolute position. Positional data \'las obtained by a Magnavox MX200 6 ChannelGPS receiver, corrected by a Scorpio differential beacon receiver and logged viaCoastal Oceanographics "Hypack" survey programme (vA). Positional data wascorrected to OSGB 36 datum.

The area surveyed \'las selected to provide information on the dynamics and type ofsea-bed in the 'key' locations designated for benthic monitoring. A total of 15 surveylines were followed providing an acoustic map of the sea-bed covering an area about4 km by 15 km (Figure 3).

2.3 Data analysis and presentation

Tables of species abundance and biomass data from replicated stations have beencompiled and summary statistics of ta.'I{a, densities and biomass presented in thefollowing sections. The analysis of species abundance data follows the approachadopted by Field el ai. (1982), namely "a search for patterns amongst the biologicalvariables with an attempt to interpret these in terms of the environmental data". Inorder to achieve this a suite of numerical programs called PRIMER (PlymouthRoutines in Marine Ecological Research; beta test version 4.0), developed byPlymouth Marine Laboratory were used.

It is important to appreciate that meaningful estimates of community speciesabundance data, from benthic sampies, is necessary before quantitative communityanalysis can be performed. This implies that adequate quantitative benthic samplingtcchniqucs will bc uscd, such as thc mini-Hamon grab.

Patterns amongst sampIes have been analysed using multivariate cluster analysis of


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species abundance data after generating sampie similarities with the Bray-Curtis(dis)similarity index on doub~e root transformed species abundance values. Sampiesimilarities were then presented as a dendrogram havi.ng been group-average-sorted.

The characterising species were identified by ranking the species within each grouppreviously identified by sampie cluster analysis (as above). The ranking of specieswas first achieved by % frequency of occurrence across each sampie group and thenby % mean dominance. This procedure produces essentially the same resuit asSIMPER analysis (at least for the present data set), but is much less complicated andtherefore simple to understand.

Physical data, in particular sediment particle size information, was also analysed usinggroup average linkage cluster analysis. However, sediment data was first standardisedand double root transformed prior to applying the Euclidean Distance index of(dis)similarity.

3. RESULTS AND DISCUSSION

3.1 Physical Environment

3.1.1 Geomorphology

Gravels that are found offshore (including Hastings Shingle Bank) generallyoriginated as fluvial or fluvio-glacial deposits which were drowned by the most recentpost-glacial rise in sea level. Approximately 18,000 years aga the sea level was about120 metres lower than at present which coincided with the most southerly advance ofthe Devensian ice sheet. The earliest incursion of sea into what is now the southemNorth Sea occurred about 10,000 years ago (BGS, D. Harrison, pers. com.).

Hastings Shingle Bank forms a distinctive feature running in an ENE/WSW directionparallel to the major tidal currents. The bank crest is cIearly defined by the 20 metredepth contour on Admiralty chart 536 (Beachy Head to Dungeness) with depths on topofthe bank typically ranging from 14 to 18 metres (CD). Towards the landward sideof the Bank (i.e. in a northerly direction) the sea-bed shallows and forms part of theRoyal Sovereign Shoals. There are, however, two areas of deeper water which cutinto the bank giving it its distinctive morphology. The southem boundary of the bankseparates the shoals to the north from the deeper water of the English Channel to thesouth. The southem edge of Hastings Shingle Bank is characterised by a sharp changein bathymetry from 15 metres to 35 metres over a distance ofabout 400 metres.

3.1.2 Tidal currents

The tidal currents in this area are strong with surface spring tides typically reaching 3knots. A number of detailed current meter surveys have been conducted on andaround the Bank. They show that the main residual in water movement is towards theNE with the dominant excursion occurring on flood spring tides (north easteriyflowing).

Ihere are 4 characteristic phases to the tidal cycle which can be described as foIIO\vs:

/CES-WGEXT 69 April/998

Biological and Habitat Assessment of Hastings Shingle Bank

!- aperiod of ebb flow which lasts on average about 4 hours (4:03 ± 0:57.15 onestandard deviation) at a heading of about 240 degrees (242.7 ± 1.19) and an averagespeed of about 43 cms'! (42.89 ± 7.85), li. there then follows a rapid southerly swingin the current prior to the commencement of the flood tide, slack water is very shortlived, with the swing in the current lasting on average 1 hour 15 minutes (1:15.12 ±0:01.29), iii. the flood tide is characterised by an initial period (lasting 1:39.48 hrs ±0:17.14) ofchanging direction from 69.75 degrees C± 1.26) through to 50.00 degrees(± 1.4) during which time there is an increase in current speed from 53.76 cms'! ±5.34 to 88.34 cms'! (± 12.38), there then follows a short period during which time themaximum flow remains at a constant direction (i.e. 50.00 degrees) before the currentstarts to ease and turns northwards, iv. the turn at the end of the flood tide is muchless rapid than the turn at the end of the ebb. For example, the current swingsnorthwards from 50 degrees through to about 240 degrees over aperiod of 3: 18.3 hrs(± 0:30.70).

3.1.3 Grab sampIe sediment particIe size analysis

Summary sediment particIe size data for each of the benthic grab and Shipek grabsampIes is geographically presented in Figure 4. HO\vever, it should be noted thatalthough full particIe size cIassification was undertaken for sampIes taken with themini-Hamon grab, only a subjective description of surficial sediments from Shipekgrab sampIes was available. Nevertheless, the sediment descriptions from both grabsand their distributions on the sea-bed were in very cIose agreement (see Figure 4).

It may be observed that there are a number of sampIes which show similarsedimentary characteristics. For example, within the proposed extraction site sampiesgenerally contain an appreciable quantity of graveI. A second group of sampies, alsowith a dominant coarse fraction, can be observed to the south west of the extractionsite. Immediately to the south, however, there are a group of sampies whose dominantsize fraction is fine sand (0.25 mm to 0.063mm), whereas over in the north east thereure a group of sampIes which have a significantly higher silt content « 0.063 mm).

A more objective approach to determine sampIe similarities based upon their physicalproperties was undertaken using multivariate cluster analysis (see data analysis andpresentation section, above). The results of this analysis are presented in Figure 5.This figure cIearly shO\vs two dominant groups of sampIes, namely those with asignificant gravel fraction and those predominantly composed of sand. A number ofmore subtle groups can be observed at a dis-similarity level of about 0.5, but thesignificance of such groups is questionable, as will be discussed in-light of thebiological data presented below.

3.1.4 Side-scan sonar survey

\Veather conditions during the side-scan survey \vere moderate (force 3 to 5) howevcr,the strong tidal 'currents at the time (the largest predicted spring tides of 1997) causeda short choppy sea which prevented the side-scan fish from being towed near thebottom, at its optimum height above thc sea-bed. Although the conditions served topartially degrade the side-scan image, the survey nevertheless revealed a number ofdistinctive bedform types (see Figure 6), namely; i. an area of mobile sediment just to

•

•

leES - lrGEXT 70 i1pril1998

N

1

Water Oepth(CD: OSGB36)

10m20m30m

o 1.25 2.5,........, I

KIlometres

- Prospectlng site- ProductIon slte:

% Sediment(mini Hamon grab - PSA dala)

• Gravel• CoarH_Sando Fine Sand11 SIIt - •

Recorded sed. type'(Shlpek grab. Obaerved al aea)

eCleanSANDeCoarH GRAVELeSandy GRAVELeGravelly SANDeSlltySAND

e

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e

e

ee

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036 E

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() '::~~;. (.~ 'v'.).) .

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'.-'(-' 0.... . ~".'-.

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50 39 NO 24 E 0 30 E

..'

---

...~......... '---......- ,-,)

\..:

-...l-

Blologlcal and Habitat Assessment of HastingsShlngle BankThe Hastings/Cutllne MarineAggregate Oredglng Association

Figura 4. Sediment characterlstlcs frommini Hamon grab and Shlpek grab sampies

March 1998

1--

2

1

o

Sediment - SAMPLES-

PIE CHARTS· Sedlme.m

~GraVel (2 -16 mm)

, Coarse Sand (0.25 - 2 mm)Fine Sand (0.25 - 0.063 mm)

• Silt « 0.063 mm)

LEAF LABELS· Bentho.• gr.1velly SAND llulJmblaiC B• sand SCOUNd GRAVEL assemblage Al

Istahle sand and GRAva aJ'emblage Alclean mobile alullly SAND assemblage Clsilty SAND anemblage Cl

. .FiKure 5. Dendrogram showing sampie groups derived from group average Iinkage cluster analysis ofparticle size data having firstbeen standardised and double root transformed. The distance measure was the Euclidean Index. Summary sediment pie-charts havebeen superimposed to highlight the characteristics responsible for the cluster groups. Leaflabels (sampie numbers) have beencoloured according to the assemblage they represent (see Figure 10).

•50 48 N

/

/,/I

.'/''"

N

1

March 19981

o 1.25 2.5,........-.j i

Kilometres

Water Depth(CD: 05GB36)

10m20m30m

- Prospectlng slte .- ProductIon slte

~ stable sand & GRAVEL

m gravelly SAND

EJ sand scoured GRAVEL

8 clean mobile shelly SAND

~ sand waves over coarse GRAVEL

042 E

-:) .:..(:: ~-.:...... ,; ...

036 E

Flgure 6. Interpretation of slde-scan sona'",data

". ~. ~

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....... ",'..) <....... '-"\.}'

Blologlcal and Habitat Assessment of HastlngsShlngle BankThe HutingsJCutline Marine AggregateDr~glng Assoclatlon

", ....\ ...-"; -',-'-..': ..•.. "')

5039 NO 24 E


the south of the proposed extraction site dominated by meguripples with a wavelength of about 10.4 metres. SampIes collected in this urea with the mini-Hamon andShipek grabs indicated the sediment was generally a clean shelly medium sand (Fig. 6,Clean mobile shelly SAND). H. an urea within the proposed extraction site which isdominated by a relatively featureless medium-hurd ground (sand and gravel sediment).There ure, however, a number of incursions of finer (sand) sediment to the south andwest, suggesting the gravel may be subjected to occasional scouring by mobile sandtransported from the sandy areas to the south (Fig. 6, sand scoured GRAVEL). iii. atransition or intermediate bedform type, between types i. and ii above, that is relativelyfeatureless and lurgely consists of a medium-soft ground (Fig. 6, gravelly SAND) withthe exception of the occasional patch of gravel showing up as much darker areas on

.the sonograph. iv. a lurge area, on the western side of the survey, which is dominatedby very hard ground composed of a stable sand and coarse gravel (Fig. 6, stable sandand GRAVEL). The transition between areas iii. and iv. is very abrupt and weIldefined, and finally v. an area to the south which is dominated by large sand wavesover hard ground. The sand waves have a wavelength of about 15.6 metres and it isconsidered that the intervening hard ground would be considerably scoured by sand intransport (Fig. 6, sand \vaves over coarse GRAVEL).

It will be shown that a combination of the geomorphology, sediment dynamics andtidal currents have a significant inf1uence on the status of the benthic fauna offHastings.

3.2 ßiological Status

3.2.1 Previous studies of aggregate assemblages

Owing to the difficulties of sampling coarse sediment using traditional quantitativesampiers, such as the Day grab, many of the published descriptions of aggregateassemblages are, at best, semi-quantitative (Holme, 1961, 1966; Davoult et al. 1988;Davoult 1990; Kenny et al., 1991, and Dewarumez et al. 1992). However, suchstudies \vere among the first to begin defining the great variation in micro-habitatsafforded by complex mixtures of sand, gravel, shell and silt. They were able tobroadly reIate the physical environmental conditions with specific community types,but precise definitions, and quantifiable links with other environmental processes suchas the amount of sediment transport, were not possible.

More recent investigations of the impacts of aggregate dredging have employed theuse of aHamon grab which is particulurly weIl suited for the quantitative sampling of

.graveIs. The application of such quantitative sampling methods has allowed, not onlythe primary biologicaI impacts of dredging to be studied (see Kenny and Rees, 1994and 1996), but also the 'key' environmental factors regulating course aggregatebiodiversity to be evaluated.

In relation to the fauna off Hastings, the account given by Rees (1987) is mostspecific, but in terms of describing thc types of fauna in relation to the sca-bedenvironmental conditions, the work of Holme and Wilson (1985) is worth furtherconsideration.

•

/CES-WGEXT 74 April/998

•

•

Biological and Habitat Assessment of Hastings Shingle Bank

Holme and Wilson provide an account of the epifauna typically associated with aclean course aggregate subjeeted to varying degrees of tidal seour by sand. They

" .". 2 . : • ,. .', .. 'surveyed an area (about 6 kill ) in the north central English Channel, using undenvaterTV cameras. The use of cameras allowed specific sedimentary dynamies to beinvestigated in relation to maerofaunal species and their behavioural responses. Threedominant eommunity types were identified, namely; i. the T;pe A eommunity whieheonsisted of a stable epifauna with a diverse sponge, hydroid, aseidian and bryozoancover, whieh was present on bed-roek, pebbles and eobbles. This eommunitydeveloped in areas where the substratum had not been seoured by sand or gravel andhad remained stable for a eonsiderable number of years. ii. the Type B communitywas again present on cobbles and pebbles but was subjected to periodic seour andsubmergenee by sand. Three sub-types of the T>pe B were identified. The first (Bi)was defined as 30 '\vell developed faunal assemblage with Polycarpa violacea" andwas notably different from the Type A on aeeount of the paueity of sponges. Thesecond (B2) was subjeeted to eonsiderable sand scour and periodie submergence bysand and gravel. Sponges ,vere absent, as were various bryozoans, notably PentoporaJoliacea, whieh had been replaeed by the more robust FlustraJoliacea. The third (B3)eommunity was defined as an "impoverished Balanus - Pomatoceros assemblage". Itwas found on hard substrata whieh were frequently seoured ,md submerged by sandand gravel. The fauna was restrieted to fast growing eolonisers whieh eould establishthemselves in the short periods of physieal stability during the summer months. Thethird major type of community, T>pe C, was deseribed as a "eobble floor eovered bysand". The dominant animals present were members of the (B2) eommunity, namelyUrticinaJelina, FlustraJoliacea and Sabellaria spinulosa.

It will be shown (see below), that off Hastings generally the same biotopes exist. Theterm biotope has been used as it ineorporates elements ofboth the physieal habitat andthe assoeiated benthie fauna. The term assemblage has also been used in preference tocommunity, since the often harsh physical eonditions experieneed by fauna in coarseaggregate deposits greatly reduees any speeies inter-dependenee whieh is implieit inthe definition of a eommunity (Peterson, 1914 and 1918).

3.2.2 Mini-Hamon grab survey

The complexity of sea-bed physieal conditions (deseribed above) affords a hugevariety ofmiero-habitats for benthic eommunities to develop off Hastings. As a resultthe total number of speeies identified from all grab sampies was very high at 303 taxa.

In order to examine sampie similarities (based upon sampie species composition) andto geographieally determine the dominant assemblage types, multivariate clusteranalysis was performed (see data analysis and presentation, section above). Theresults of such analysis are presented in the form of a dendrogram in Figure 7.

It may be observed that a number of sampies have been grouped at varying levels ofsimilarity, namely; at about the 25 % level there are three major assemblages types.These ure assemblage type A, type Band type C. The type A assemblage was themost diverse and most closely reprcsents the Holme and \Vilson community 7)pe B.It is subjeeted to periodie disturbanee by sand in transport as evidenced by thedominant presenee of Balanus crenatus. The habitat is dominated by coarse gravel.


70

Figure 7. Dendrogram showing sampIe groups at varying levels of similartity basedupon the Bray-Curtis similarity index applied to macrofauna abundance data(>1mm) and double root transformed.

80~ .&.:. J,. l-.l ~ t.,) t.,) t.,) t.J \-.1 N l',J ~ t,,) t,,) looo' W ~ ~ W t.J \-.1 \.J to.J ~,J N I>,) t-.,) ~ \.0 -...1 0\ 0\ 0\ .. 00 t,,) ... t.J - ... - ...... N ...... - Ot CJJ CJJ looo' N___ O\~O\O\~~~~~O~O~~~~-~~~~~~~WA n~~ ooONooo\WWW-\.ON- NOt.nC"~~ n?~n~n~C"J C" L-S!nC"~n~l:T'~ ,t ,n t ~C"n ,

C2 Cl .-\2 Al B..-----------------,I gravelly SAND assemblage B

sand scoured GRAVEL assemblage Al

I stable sand and GRAVEL assemblage Alclean mobile shelly SAND assemblage Cl

• silty SAND assemblage C2

•

•

. "


However, there are two sub-types defined at about the 35 % similarity level whichmay be explained by differences in the stability ofthe sediment.

For example, Assemblage Al (stations 8, 4, 6a, 6b, 6c, 7 and 9) was the most diversehaving an average of 64 species and 428.3 individuals per sampIe. The dominantsolitary taxa are presented in Table 1 and include the barnacle (Balanus crenatus), the'ross reer worm (Sabellaria spinulosa) and the polychaete (Lwnbrinereis latreilli).Of the colonial epifauna Table 2 indicates that the dominant taxa present were thehydroid (Abientinaria abientina) and the bryozoans (Flustra foliacea and Escharellaimmersa). The ubiquitous presence of Flustra foliacea in this assemblage issignificant in that it most closely represents the "weIl developed BI epifuanal"community of Holme and Wilson. Assemblage Al is regurded as the most stableassemblage type off Hastings, as indicated by the presence of a lurge number colonialepifauna taxa which include several species of sponge (see Table 2).

Assemblage A2 (stations 14, 23a, 27b, 27a, 27c, 28a, 28b, 23c, 23b, 31) differs fromAl in that it is subjected to more frequent scouring by sand. The total number ofcolonial epifaunal species is fewer and there is not the dominant presence of Flustrafoliacea or other bryozoans. Assemblage ....12 most closely represents Holme andWilson community T;pe B2. The average number of species and abundance ofindividuals per sampie was 44.4 and 290.9, respectively.

Assemblage B represents an impoverished version of the type Aassemblage. Thepredominant sediment type is course sand with a smaIl amount of gravel and as such ithas many more species characteristic of a sandy sediment such as the small pea-urchinEchinocyamus pusillus (see table 1). Nevertheless it retains a number of colonialepifauna species similar to assemblage A and therefore has been clustered withassemblage A sampIes in the dendrogram (Figure 7). The average number of speciesand abundance of individuals per sampIe was 16.4 and 33.4, respectively.

Assemblage C was generaIly dominated by species characteristic of mobile sandysediments such as the infaunal polychaetes, Pectinaria koreni, Ophelia borealis andSpiophanes bombyx. Within this assemblage there ure two sub-assemblage types,determined by the relative amount of fine sand and silt present in the sampIes.Assemblage Cl (stations 25b, 25a, 25c, 24a, 24c, 26a, 26c) consisted of species mostassociated with clean mobile coarse sands such as those previously mentioned. Theaverage numbcr of species and abundance of individuals per sampIe was 16.4 and33.4, respectivcly. Assemblage C2 (stations 37, 26b, 41a, 41b, 41c) consisted ofspecies most associated with silty fine sands and was dominated (in terms ofbiomass)by the burrowing sea-urchin (Echinocardizmz cordatum). This assemblage representsthe least diverse and had the most restricted epifauna (see Tables 1 and 2). Theaverage number of species and abundance of individuals per sampIe was 12.6 and53.4, respectively.

Relationship between habitats and fauna

Traditional means of explaining biologieal diffcrences betwcen sampies has rclied onobserving differences in sediment particle size data taken from the same sampies. Inareas where the sediments are in equilibrium the correlation is often good, but in arcas

ICES- waEXT 77 ;tpri11998

...~~CI)

I:::cj

~"';

ASSEMBLAGE: B ASSJj=MBVAGE: Al ASSEM~LAGE:Al ASSEMffl·!§Es Cl ASSEMBLAGE: C2

Spf'clel ·/.MD ID: Srrcl.. ~ lli: ~ ~ °AlF Sp.cltr hW2 ID: h ecl•• liM1! ID:Echinocyamus pusiJIus IU ~7.5 ßalanps cre'lalus 578 1000 Scal/bresma IrIf1atum 2.8 1000 Pectinaria koreni 12.4 100.0 Magelona rnlrabilis 36.7 1000

ScaJibregma inflatum 99 875 Sabe/laria sl1inlllos(l 3 1 1000 Lumprltlerl.f latrell/i 18 100.0 Ophe/la borealis 6.0 85.7 Spiophanes bombyx 10.1 100.0

Sotomastus larericeus 68 ~75 /..lImbl'ineris larreiIJi 17 1000 Balanus crlfnatus 638 90.0 Lllmbrlneris lall'eiJli 56 8U Pectinaria korent 4 1 800

Ncmcrtea 58 875 Syllis $p. u 100 0 Gon(ada mflculata 0.4 900 Nephtys cirrosa 30 8U Bathypore/a pelag/ca 79 60.0

Syllis sp. A .5) 87.5 folycirnls SR· 09 1000 GIYOlll'a alqa 04 90.0 Glycera oxycepha}o 2.6 857 Abra pr/smatlca 2.6 60.0

G~vcera lapidum 2.2 875 (JIycel'a lap/Jum 07 1000 onChidoridrlle 2.1 800 SC(llibregma /nflat- 43 71.4 Ech/nocard/um cordatum 2.6 60.0

LlImbrineris la/reilli 29 750 !VorO"fOstus Jater/ctjus 06 1000 Plict/narta orenl 1.4 800 Splophanes bomhyx 8.1 571 Nephtys cirrosa 2.2 600

N<!phryssp. 14 750 Spisulp elliptlca 06 100 0 EchiflOcya'f/Us pusil/us 1.4 80.0 Pholoe /"oma/a 30 57.1 Angqlus tenuis 79 40.0

Syl/is sp. 5 I 625 (lct/n/oria sp.A 3 I 857 Notqmastu{ latericeus 04 800 Nemertea 2.6 571 Poecilochaetus serpens 3.4 40.0

Polycirrus sp. 2.2 62.5 fomatocero", triqueter 13 85.7 Cau(/lIrlllll41 zetland/ca 04 800 Abra pri.'lfflll/ica 2.6 42.9 Ampe/isca sp/nipes 3.0 40.0

Aonides pallcibranchiata 36 WO Syllis fP. A 12 857 PolYF/rrlls Ip. 0.3 80.0 Nematoda 60 286 Abraalba 1.9 40.0

Polycirrinae 36 '00 f:chinocyamlfs pus/lllIs 10 857 Nlll11llrtlla 1.2 700 Bathypore/a pilosa 3.4 286 Ophelia borealis 1.1 40.0

~ Spisula e/liptica 29 500 Nel11eJTlea 09 85.7 Ampflli.Jca -Ipinipes 1.2 700 Poeci/oehae/us serpens 1.7 286 Nemertea 1.1 40.000

Ophelia borealis 12 500 Nematoda 08 85.7 Aonldlls oxycephala 0.7 700 Nephtys "p. u ::86 Cau/leriella zetlandica \.1 40.0

Spiophanes bombyx 12 500 IlamlQthoe .It 07 85.7 Cau(/lIrlella alata 0.7 700 Bathyporilla pelagica u ::86 Mysel/a biqentata \.1 40.0

G~vcera o:cycephala 10 500 ~abellidae 0.6 85.7 Galqthlla /nlemJedia 0.7 70.0 Spisula eJ/ipt/ca 0.9 286 Corbula gibba 1.1 40.0

Maldaniduc 10 500 ,4onidrs pallf/branch/o/a 06 85.7 Aonldes pallcibranchiala 0.4 70.0 Spionidae 0.9 286 Chaelozone setosa 0.7 40.0

Uro/hoe marinIl 17 375 fsamrflechinlls mi/iaris 05 857 Psa,_ch/f/u.J ml/iaris 0.3 700 Nere/s lonJli.Jsima 0.9 286 Ne:matoda U 20.0

Nemalooa 11 ill ,.lctiniaria sp.B ~ 851 Ampllarllte I/nds',oemi 11 m Ac//n/urla $p.B Q..2 ;M Spio armata U 12J!

Ave. Species 121.6 ± 61 1~~fllUI I,.·.... + llU~ 16.4 + 6.9 12.6 + 4.7

Ave. Abundnnce 1,.8 + 25.7 .mU'+l~o..~ 290.9 + 1~5;2 33.4 + 20.S 53.4 + 30.1

Table 1. The top 20 SPCCiC8 cl\lIracleristic of e~ch major .,.;efllblage idcntifi,d "y c11J&<lr ",~Iy.i. (lII'e Figure 10) ~rfonned on quantitative abundanue datA (>1nun) f""" mini HaRlon grabs.Ranking \WS by rrcquency 01' sp.:cies tlccur~nce acrpss S<lmplcs ~Ihi'l ea<:~ grOUV (%F) anjIthen by their mean abllnd.w:e. Le. mean domlnance (%MD)Average numher 01' spccies and abundance is expre~ per lIlImple ",,;t arc'l. (Il. J m'). Erron are: one Stand'ard De"i<.tiort on a Saml'le mcm.

HUlIn'J' Shf'QIt BIN< Entlrormn" Asseumer1

•

ASSEMBLAGE Al

....R~

I

~ ASSEMBLAGE B

~ Slwci.. :!!..E""'iEscharella immersa 50.0

Hydrozoa 37.5

Sertulariidae 25.0

Abientinaria sp. 25.0

Abientinaria abientina 25.0

Cel/aria sp. 25.0

Clathrina coriacea 12.5

Hemiastercllidae 12.5

Haleeiurn sp. 12.5

Plumularia setacea 12.5

lAgenipora lepralioides 12.5

Flustra foliacea 12.5

Cel/aria jistulosa ill

-.)\0

Abientinaria abientinaEscharel/a immersaFlustra jb/iaceaCel/aria jistulo.yaPlumularia setaceaCampanulinidaeAlyconium digitatumScrupoce/laria .yp.Nemertesia sp.SertulariidaeClathrina coriacea

Diphasia rosaceaGonothyraea loveniAlcyonaceaEunicel/a verruco.YaMicropore/la ciUMaElectra pi/osa

100.0

100.0

100.0

llJ.3

50.0

50.0

50.0

50.0

33.3

16.7

16.7

16.7

16.7

16.7

16.7

16.7

1U

ASSEMBLAGE A2

~

Campanul inidaeEscharella immersaAbientinaria abientinaPlumularia setaeeaFlustra foliaeeaCellariaflstulosaNllme;·teJia Jp.

Clathrina eoriaeeaEscharella Jp.Schi:omauella aurieulataScrupoeellaria Jp.

ASSEMBLAGE Cl ASSEMBLAGE C2

:tt.E ~ :!!l: ~ :t!r

100.0 Plumularia Htacea 42.9 Abientinaria abientina 80.0

90.0 Sertulariidae 42.9 Plumularia setacea 40.0

40.0 EJeharelJa imfPHrsa 28.6 Sertulariidae 40.0

20.0 Abimti,lOria abientina 28.6 Halisarca dujardini 20.0

10.0 CamPßllulinidae 14.3 Athecata 20.0

10.0 Nemertesia Jp. 14.3 Anthoathecatae 20.0

10.0 Cellaria ",p. 14.3 Figularia figularis 2M10.0 DepaJtrum eyathiforme 14.3

10.0 Diphasia sp. 14.3

10.0 Obelia Jp. 14.3

ill.Q Bieellariella ciliata 14.3

ParaJmittina trispinosa 14.3

Celleporella hyalina 1U

Ave. Species /2.8 + 1.7 17.3 + 1.7 13.2::!: 1.4

Table 2. Epifaunal colonial species corresponding to each major assemblage id\:lltilied hy cluster analysis (see Figure 10). Ranking was by frequency ofspecies occurence across sampieswithin each group (%F). Average number of species is c:xpressed per sanpie unit area (0.1 m2

)

Errors are olle Slwulard Deviation on a SampIe mewl.

B,ologiCal and Habitat Asu..menl 01 Haslings Shingle Sank

The Hastlngs!Culhne Mann. Aggregate Oredgulg Associallon M.rch 1996


where the sediment is in transport, and not so v·,.eIl sorted, there is little correlation.between sediment particle size and the type of fauna. Areas of coarse aggregategenerally fall into the second category. This is highlighted by observing the results ofparticle size analysis in the present study.

For example, in Figure 5, the particle size analysis (PSA) clearly separates two groupsof sampies, Le. those which have a dominant gravel fraction, and those which have adominant sand fraction. Whilst such analysis may account for the broad separation ofassemblage types .11, and C, presented in Figure 7, it can not explain the clearbiological differences within assemblages .11 (i.e. Al and .112) and C (Cl and C2), orassemblage B. Clearly there are factors other than PSA involved in explainingvariations in the benthos associated with coarse aggregates.

The map ofhabitats, interpreted from the side-scan sonar mosaic (Figure 6), combinesinformation on the stability of the sea-bed with bedform topography and sedimenttexture. It can be seen that the geographie distribution of habitats in Figure 6correlates weIl with the distribution of assemblage types presented in Figure 8.Indeed, Figure 6, may be used to predict the biology in areas which have not yet beensampled. For example, the most southem habitat description from the side-scan sonarindicates an area of sand waves overlying coarse ground (probably gravel or rock).This type ofhabitat was observed by Holme and Wilson (1985), but was not sampledduring the present study. They describe it as a "cobble floor covered by sand". Thedominant animals present \vere members of the (R2) community, namely Urticinafelina, Flustra foliacea and Sabellaria spinulosa. It may be expected that similarorganisms would be found in this area south of Hastings Shingle Bank.

3.2.4 Predicted effects of dredging

The present study cIearly demonstrates the significance of natural sediment dynamics,combined with in-situ substrata, in determining the type of benthic assemblageencountered. Within the proposed extraction site, a relatively rich assemblage(assemblage .112) can be found. However, the benthos in this area is subjected to adegree of natural disturbanee caused by periodic scouring of sand and gravel. Thishas the effeet of significantly reducing the diversity of colonial epifauna found withinthis assemblage. Dredging will cause further physical disturbance, and as such it maybe expected that the resultant fauna, in areas of sea-bed not direetly removed bydredging, \vould more cIosely represent assemblage B. However, the potential forrecovery following dredging is high, owing to the absence of any long-lived and slow

.growing taxa in assemblage A2 prior to dredging.

Potential seeondary impacts of dredging to the south of the proposed extraction site,caused by the redeposition of fine sediment derived from dredge plumes, is consideredto be extremely unlikely. In support of this assertion the following points may beoffered, i. data from the side-scan sonar survey clearly shows thc area to thc south ofthe extraction site to be dominated by sand waves, which presumably have associatedwith them a considerable amount of sediment in suspension during storms or springtides. H. tlle associated dominant benthic fauna is adapted to living in mobile finesediment environments. iii. the sediments to the south are all 'clean' with very littleamounts of silt indicating that these areas are not a natural depositional area for fine


N

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• .table sand & GRAVEL ...emblage A1

@ ,and Icoured GRAVEL "Iemblage A2

• gravelly SAND ....mb/age B

fb mobile Ihelly SAND ....mblage C1

• sllty SAND aslemblag. C2

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(fl42 N

<.:-' .~'~:: (.' \;...).) .

50 39 NO 24 E 0 30 E

..\ ....-~.~ .'., ....-::..._... ..'

00-

Blologlcal and Habitat Assessment of HastingsShlngle BankThe Hastings/Cutline MarineAggregate Oredging Association

Figura 8. Benthlc biotopes

March 1998


sediment. iv. tidal current survey work indicates no net transport to the south.

4. CONCLUSIONS

1. A total of 53 benthic sampIes were collected from 32 grab stations. A total of 9stations were replicated for temporal monitoring purposes.

2. A total of 303 taxa were recorded, providing the most comprehensive species listoff Hastings to date.

3. A side-scan sonar mosaic covering 15 km by 4 km established the dominanthabitat types within, and adjacent to, the proposed extraction site. A total of 5benthic habitat types were identified, namely; i. stable sandy gravel, ii. gravellysand, iii. sand scoured graveI, iv. clean mobile shelly sand, v. sand \vaves overcoarse gravel.

4. Multivariate analysis of the macrobenthic grab data revealed 5 major benthicassemblage types, namely; i. a stable sand and gravel assemblage (Al) dominatedby Balanus crenatus and Sabellaria spinlilosa, H. sand scoured gravel assemblage(A2), dominated by infaunal polychaetes Scalibregma inj/atum and Lumbrinerislatreilli, iii. gravelly sand assemblage (R), dominated by Echinocyamlls plisillllSand Scalibregma inj/atllm, iv. mobile shelly sand assemblage (Cl), dominated byPectinaria koreni and Opelia borealis, v. silty sand assemblage (C2), dominatedby },fageloma mirabilis and Spiophanes bombyx.

5. The complement of species identified, and in particular the dominant taxa namedabove, are widely found in coarse mixed sediments off the UK.

6. Correlation of faunal assemblages with PSA data was of limited value. Forexample, PSA data indicated no separation between assemblages Al and A2, orCl and C2, hO\vever, correlation bet\veen side-scan benthic habitats and faunalassemblages was very good.

7. Habitat data from the side-scan mosaic predicts an additional faunal assemblage tothe south of the proposed extraction site (not yet sampled) which would coincidewith sand waves over a bed of coarse gravel.

•


•

•


5. REFERENCES

DAVOULT, D. (1990). Biofacies et structure trophique du peuplement des cailloutisdu Pas de Calais (France). Oceanol. ACTA, .11, (3), 335-348.

DAVOULT, D., DEWARUMEZ, J.-M., PRYGIEL, J. and RICHARD, A. (1988).Benthic communities map of the French part of the North Sea. Etudes etCartographie, Lille, France.

DEWARUMEZ, J.-M., DAVOULT, D., SANVICENTE ANORVE, L. E. andFRONTIER, S. (1992). Is the 'muddy heterogeneous sediment assemblage'an ecotone between the pebbles community and the Abra alba community inthe southern bight ofthe North Sea? Neth. J. Sea Res., .N. 229-238.

DICKSON, R. and LEE, A. (1972). Study of effects of marine gravel extraction onthe topography ofthe sea bed. ICES., C.M., 1972/E;25, pp19 (mirneo).

ETS Ud. (1997). Hastings Shingle Bank tidal current survey: 14-16 September 1997.Environmnetal Tracing Systems Ltd., Rossarden House, Argyll, Scotland.,pp8.

FIELD, J. G., CLARKE, K. R. and \VARWICK, R. M. (1982). A practical strategyfor analysing multispecies distribution patterns. Mar. Eco!. Prog. Ser., ~, 3752.

HOLME, N. A (1961). The bottom fauna ofthe English Channe!. J. Mar. Bio!. Ass.UK.,11,397-461.

HOLME, N. A. (1966). The bottom fauna ofthe English Channel: 11. J. Mar. Bio!.Ass. UK., 46, 401-493.

HOLME, N. A. and WILSON, J. B. (1985). Faunas associated with longitudinalfurrows and sand ribbons in a tide-swept area in the English Channe!. J. Mar.Bio!. Ass. UK., 65, 1051-1072.

KENNY, A. J., and REES, H. L. (1994). The effects ofmarine gravels extraction onthe macrobenthos: early post dredging recolonisation. Marine PollutionBulletin, 28., 7., 442-447.

KENNY, A. J., and REES, H. L. (1996). The effects ofmarine gravel extraction onthe macrobenthos: results 2 years post-dredging. Marine Pollution Bulletin,32.,8/9.,615-622.

KENNY, A J., REES, H. L. and LEES, R.G. (1991). An inter-regional comparison ofgravel assemblages off the English east and south coasts: Preliminary Results.ICES., CM., 19911E:27, pp15 (mirneo).

PETERSON, C. G. J. (1914). Valuation ofthe sea, 11. the animal communities ofthesea bottom and their importance for marine zoogeography. Report of theDanish Biological Station, 21, 1-44.

PETERSON, C. G. J. (1918). The sea bottom and its production of fish-food. Asurvey of thc work done in connection with valuation of the denmark ,vatersfrom 1883- 1917. Danish Biological Station Report, 25, 1-62.

REES, H. L. (1987). A survey of the benthic infauna inhabiting gravel deposits offHastings, southern England. ICES., CM., 1987/L:19, pp19 (mirneo).

SHELTON, R. G. J. and ROLFE, M. S. (1972). The biological implications ofaggregate extrac!ion: recent studies in the English Channe!. ICES., CM.,1972/E:26, pp 12 (mimco).

ICES- WGEXT 83 Apri11998

ANNEX V Item I Letter from Chairman ACME.

--IPlanning and International Relationsllead oe Department Stig R. Carlberg

23 lanuary 1998

Dr S.l De GrootNetherlands Institute for Fishery ResearchP.O. Box 68NL-1979 IJmuidenThe Netherlands

DearBas,

With this letter I want to thank )'ou and )'our working group WGEXT for )'our hard work and particularly for theextensive suevey )'ou did on the efTects of extraction of marine sand and gravel on the Baltic ecosystem. I ampleased to tell )'ou that ACME was very impressed and happy with your producl and the sun'ey is in fuHincorporated in the 1997 report of ACME.

Since information was missing from some of the Baltic countries ACME discussed the usefulness of referring theitem back to WGEXT for another turn in case you could find more information. Later we found out that withinIIELCOM another suevey was carried out on the same subject under German leadersbip and they had found more orless the information that WGEXT did not have access to. Obviously parallel activities were going on wbich causedconfusion in HELCOM. Within that framework Danmark now takes the lead in order to merge the different papersinto one background document for a Draft HELCOM Recommendation. So, quite obviously, the result your grouphas produced was vcry uscful to HELCOM. Many thanks for fine job which was greatly appreciated by ACME andalso IIELCOM Environment Committee. Since it is impossible for me to participate in )'our meeting I ask )'ou toconvey to the group the appreciation from ACME.

Below follows a general text that I send to all chairmen ofworking groups that now belong - or until recentlybelonged - to AC!'.ffi. Your working group is transferred from MEQC to its successor~ the Marine HabitatCommittee. Nevertheless, the text may be of same interest to )'OU as ageneral information. However, I would like)'OU to ask you to initiate in your group a discussion about the last ilem in that text~ the usefulness of theenvironmental work carried out by ICES!

On 12 February 1997 I \\Tote you a letter in which I introduced myself as the new Chairman of ACME andexplaining some ofthe changes going on in leES \\ith a major re\ision ofthe committee structure etc. I alsoindicated that this may lead to a change in the chairrnanship of ACME already after one year.

In the follo\\ing I will give you some infonnation from the lCES Annual Science Conference and the StatutoryMeeting held in Baltimore in September 1997 and the changes agreed so far. .

•


. '{" .~. .".. ~.' ~

•

Tbe ICES Delegates decided that it was not feasible to hold elections in the two advisory committees already afterone year and therefore I am continuing as ACME Chairman until the end ofmy original mandate, which is 31October 1999. However, since the strueture ofthe science committees was revised there was also a discussion in theConsultative Committee about the allocation ofworking groups between the committees.

This subject h3d been thoroughlydiscussed in ACME at our meetings both in June 1996 and 1997. ACMEconduded that, even though the resuits from agreat number ofworking groups are absolutely essential to the workof ACME, it is logical th3t scientific working groups belong to the science committees. Tbe most important aspcctfor ACME is not to be a parent committee for working groups but to have access to working groups and theirresults. We also discussed the possibility ofdual parentship "ith ACME and science committees for those workinggroups th3t ACME is regularly rel)ing on. However, "dual parentship" invokes some administrativecomplications concerning coding and distribution ofworking group reports ete. and, therefore, this system \\iIlprobably not be used at the prescnt time.

As a conscqence ofthe discussions the Consultative Committcc preliminary dccided (a definite dccision "ill followin June 1998) that the following working groups "ill be transferred from ACME to the new Marine HabitatCommitte which replaces the old Marine Emironmental Quality Committee (MEQC): MCWG, WGMS,WGBEC, WGEAMS and WGSAEM. WGITI.IO and the study group SGBWS, duc to their advisory character,rernain in AC11E. SGMBIS, finally, has been dissolved and the Council has rccommended that it should be setup as an joint ICES/GESMIP working group.

The reports of these working groups \,ill always be rcfcrenced to ACME and I can assure you that this newarrangement does not reduce the ACl\1E interest in your work. ACl\1E "ill continue to follow your work doselyand give spccific tasks to your group to cater for the ICES advisory function.

On the other hand, SGQAC and SGQAB (with its subsidiary workshops and training courses) are transferred fromMEQC to ACME. I \,ish to welcome you "to the family" and can assure that this administrative change mean verylittle in practice for you or the groups since the entire output from your working groups has been geared for theICES ad,isory function from the very beginning. FinaIly, SGQAE and SGMPCS stay "ith ACl\1E and also forthese groups there are no changes in the relation to the parent committee.

In all cases, to whatever committec a working group belongs, the same basic rule applies: tasks given by ACl\1E(and ACFM) have to be completed with the highest priority in the meeting in order not to dclay the advisoryservice! I

However, there are some other essential matters I would Iike to discuss "ith you. ACl\1E produces two kinds ofad,ice. The first kind is in direct respons to questions from international commissions (i.e. HELCO~1 and OSPARin the environmental sector) and sometimes also from indi\idual member countries. The second kind ofadvice isproactive - i.e. it has not becn spccifically requested - and the intention of ACl\1E is to assist member countries bypro,iding good service. This advice is ofa more generic type and, therefore, potentially of interest to many, or all,member countries. There is in ICES a discussion concerning full cost recovery from the commissions to theSccrctariat for running ACME (and ACThI) meetings and other administrative costs ofproducing the advice thecommissions have requested. Some delegates have the opinion that consequently ACME should deal only withthe ad,ice that is paid, i.e. it has been rcquestcd by a commission (with the exception that also individual membercountries could also rcquest spccific advice). In the past and in the immediate future a lot ofthe rcsults ofthe workin emironmenta11y rclated working groups have been publicised and made available through the ACME (andprcvious ACMP) reports. Thercby your results got recognizcd whether they had been asked for by a commission ornot!

It is intended that within the new committee structure each science committee "i11 be given a real job to do. Part ofthis should be to critica11y review the result from its Olm working groups and /0 prepare itfor /he advisorycommit/ees. This is part ofa strengthened quality assurance procedurc ofthe ad\isory process and ifwe can find theright working procedures this "ill greatly assist the ad\isory committees and I believe it \\ill also make the sciencecommittecs more interesting. The scicnce committees have been given the task to work out a five year science planduring the next year. No doubt the Chairman ofthe Marine Habitat Committee, dr. Jarre-Teichman, "ill contacther working groups to discuss La. these matters.

However, there does not exist any mechanism for the science committces to make the working group results kommexcept through the working group reports and these are in reality available only for group members and some oftheattendees of the Annual Scicnce Confercnce (Le. those who are quick enough to pick the reports before the copicsare exhausted).

If AC?-.rn were to deal only with the items spccifically requested by the commissions (and sometimes also by amember country) and not \\üh the other scientific working group results in a pr03ctive way the ACl\1E wouldgradually loosc contact "ith the basic science in ICES, the quality ofthe advise would gradually get lower, and atthe same time ~'our results would be much less visible.


Without interfering with the responsibilities ofother committee chairmen I think it would be very important and ofmutual interest ifyou would discuss these aspects with your working group at your next meeting and give feedback to me as weH as to your science committee chairman.

I would also encourage'you, and your working group members, to discuss this with your official national delegatesto ICES to make them realise that by utilising the strength and the competence of the environmental side of ICEStheir countries get much more benefit from their annual contribution C'the membership fee") .

I wish every success for your work and your endevour to make the work in your ICES group successful and useful!

With my best personal regards

( ,

'-!_~ ~ ('--~Stig R Carlberg .Chairman ofACME

PLEASE NOTE: From 9 February I have new phone and fax numbers:Phone +46 31 751 8976 Fax: +4631 751 8980Centralswitchboard for the entire SMHI: +46 11 495 8000 (yES, it is area code 11, not 31!)

Copy: Janet Pawlak,Astrid Jarre-Teichman, Chairman ofthe Marine Habitat CommitteeACME rnernbers and alternate rnernbers (the general text ofthe letter)

•

•


INTERNATIONAL COUNCIL FOR THE EXPLORATION OF THE SEA

CONSEIL INTERNATIONAL POUR L'EXPLORATION OE LA MER

I

ANNEX V Item 2 Letter on 1997 HELCOM EC Meeting with attachment from lCES Secretariat.

Dr S. de GrootNetherlands Institute for Fisheries ResearchP.O. Box 68NL-1970 AB UmuidenTHE NETHERLANDS

Our Ref: C.8.r

Dear Bas,

General Secretary: Proiessor Christopher C. E. Hopkins

26 February 1998

•

Janet asked rne to send you the enclosed infonnation from the 1997 HELCOM EC meeting.

As soon as I receive the contact data for the Danish representative responsible for cornpiling the paper fürsubmission to EC 98, I will pass it on to you. .

Melodie arl 0

Departm SecretaryEnvi ental Processes

encls.


5.20 The Committee welcomed the information that Poland is al ready in aprocess of establishing sanctuaries, and invited EC NATURE to take therecommendation by ICES into account in their future work.

5.21 The Committee welcomed the plan by Poland to restare and protect thestock of the grey seal in the waters of the Gulf of Gdansk IEC 8/97. 5/14).

5.22 The Committee invited the Contracting Parties to support the ongoing workto develop fishing gear and methods to minimize damage and lass caused by seals andthereby to minimize the conflict between seals and fishermen IEC 8/97, 5/15).

5.23 The Committee took note that several Delegates at EC NATURE 7/97supported the idea of having a project on seals and possibilities to enlarge it to coveralso harbour porpoise and decided to propose for adoption by HELCOM 19/98 a"Project on Marine Mammals". The project proposal agreed by the Committee is

./9 contained in Annex 9 to this Report.

5.24 The Committee particularly ill.e.d. Denmark to consider its possibility tonominate an experienced project manager who would be capable of handlingconflicting issues. In case Denmark will not, however, be in a position to nominate aproject manager, the Committee invited Sweden and Finland to consider theirpossibilities.

5.25 The Committee took note that EC NATURE 7/97 thoroughly consideredissues related to monitoring of BSPAs and that the deliberations of the meeting havebeen further submitted to the Project Manager of CMP.

5.26 Regarding the Lead Country role for bird issues the Delegation of Denmarkregretted that they were not able to confirm their position yet, but were requested bythe Committee to consider the issue after the Meeting and inform the Secretariat,accordingly.

5.27 The Committee took note of the background document concerning marineand sand gravel extraction in the Baltic Sea by Germany IEC 8/97, 5/4). the advice byICES IEC 8/97, 5/9) and comments submitted by Estonia IEC 8/97, 5/19) and DenmarkIEC 8/97, 5/21). The Committee welcomed the after by Denmark to combine thedocuments by ICES, Germany and Denmark and to submit a revised backgrounddocument for consideration of EC NATURE 8/98.

5.28 The Committee invited EC NATURE to consider the after by ICES to havea joint meeting in 1999 in case further information will be needed.

5.29 After detailed consideration of the comments by Poland IEC 8/97, 5/131,Finland IEC 8/97, 5/18), and Denmark IEC 8/97, 5/21) by the sessional drafting groupthe Committee proposed the draft HELCOM Recommendation concerning marinesediment extraction in the Baltic Sea Area for adoption by HELCOM 19/98 as given in

./10 Annex 10 to this Report.

Study reservations were given by Denmark, Finland and Germany. Denmark proposedto inc(ude under point B 2 in the draft Recommendation "water areas of water depthbelow 6 metres".

5.30 The Committee reguested the above mentioned countries to da their utmostin order to be able to lift the study reservations by the end of this year.

r


ANNEX V Item3 Background document conceming marine sand and gravel extraction in the Baltic Sea produced byGermany for HELCOM EC. [NOTE: This is a revised version of EC 8/97 5/4.]

.e

HELSINKI COMMISSION - Baltic MarineEnvironment Protection Commission

Working Group on Nature Conservationand Biodiversity (EC NATURE)Eighth Meeting

Neringa, Lithuania25-28 May 1998

Agenda Itern 9

EC NATURE 8/989/2

9 April 1998

EFFECTS OF SAND-GRAVEL EXTRACTION

Marine sediment extraction in the Baltic Sea; background document

Submitted by Gerrnany


Marine sediment extraction' in the Baltic Sea

Background Oocument for HELCOM, Environmental Committee (EC), EC NATURE

compiled by Germany Rev. Version March 1998

C. Herrmann (0), J. Chr. Krause (O),N. Tsoupikova (RUS), K. Hansen (OK)

1. Introduction eExploitation of marine sand and gravel resources has already a rather long tradition insome parts of the Baltie Sea area. However, in recent time the economieal interest inmarine sand and gravel extraction has increased eonsiderably for different reasons, andso has the amount of extracted material. The reasons why marine sediments have become more and more interesting for industrial exploitation are:

• increased awareness of environmental and social eonflicts of terrestrial mineral extraction (Ioss of arable land, permanent changes of the landseape, conflicts with nature conservation aims, impacts on ground water resources, conflicts with human housing and recreation due to noise, dust, transport, impacts on the scenery etc.)

• increasing legal restrietions for exploitation of terrestrial resources in many countriesas a consequenee of environmental considerations and diminished public acceptanee

• progress of extraction techniques which facilitate exploitation of marine sediments

• advantages of marine sediments with respect to quality, availability, and ease oftransport and delivery in many cases •

However, although not as easy visible as with terrestrial extraction, marine sediment extraction also may cause negative implications on the environment, feeding conditions ofsea ducks and fish, fisheries and coastal protection. Beginning in the 1970'ies the scien-tifie interest has been focused increasingly on the implieations of marine sediment extraction. Comprehensive work has been done, inter alia, by the International Council forthe Exploration of the Sea (ICES). Already in 1975 ICES has published its first "Report ofthe Working Group on Effects on Fisheries of Marine Sand and Gravel Extraction" (Res.Rep. 46). In 1986 the ICES Working Group on the Effects of Extraction of Marine Sediments on Fisheries was convened with the aim of increasing the knowledge and understanding of the impact of marine aggregate extraction upon fisheries in particular, andthe marine environment in general. The information gained was compiled in the "Reportof the ICES Working Group on the Effects of Extraction of Marine Sediments on Fisheries" (1992), which also includes a "Code of Practice for tl1e Commercial Extraction ofMarine Sediments (including mineral and aggregates)". In the following years ICES AC-ME (Advisory Committee on the Marine Environment) has elaborated several guidelines

" .

leES - lrGEXT 90 Ltpril1998

I .

and recommendations:

I. "Guidelines for environmental impact..a~sessment of marine aggregates dredging"(draft, ACME report 1993) .

11. "Guidelines for environmental impact assessment of marine aggregates dredging (ACME report 1994)

111. "Environmental effects monitoring of extraction of marine aggregates" (ACMEreport 1995)

In the frame of HELCOM so far not very much consideration was given to the ecologicaleffects of marine sediment extraction. Article 12 of the Helsinki-Convention refers to theprevention of pollution from exploration and exploitation of the seabed and its subsoil.However, the detailed regulations as given by Annex VI of the Convention exclusivelyaim on the prevention of pollution incidents of offshore oil and gas exploration and exploitation. The broad figure of environmental implications resulting from exploration andexploitation of mineral resources from the seabed neither is covered by Article 12 nor byAnnex VI. Until now, there is also no HELCOM Recommendation concerning mineralextraction from the seabed.

However, the mandate of HELCOM to consider the comprehensive ecological aspects ofmarine sediment extraction can be derived from Articles 3 (Fundamental principles andobligations), 4 (Application) and 15 (Nature conservation and biodiversity) of the Convention:

Article 3 (1) establishes the general aim of the ecological restoration of the Saltic SeaArea and the preservation of its ecological balance.

According to paragraph (2) the precautionary principle shall be applied when there isreason to assume that Iiving resources or marine ecosystems are harmed by direct orindirect introduction of substances or energy.

Article 4 (1) states that the Convention shall apply to the protection of the marine environment of the Saltic Sea Area which comprises the water body and the seabed including their living resources and other forms of marine Iife.

Article 15 obligates the Contracting Parties to take individually and jointly all appropriatemeasures to conserve natural habitats and biological diversity and to protect ecologicalprocesses. Such measures shall also be taken in order to ensure the sustainable use ofnatural resources within the Saltic Sea Area.

Recognizing the ecological implications that marine sediment extraction may have HELCOM has addressed the problem in most recent times. The sixth meeting of the HELCOM Environment Committee (EC 6, 1995) has requested EC NATURE to consider effects of sand and gravel extraction and the advice by ICES on this issue (document EC6/15, paragraphs 6.38-6.39). The seventh meeting ofthe Environment Committee (1996)took note of the concern expressed by EC NATURE regarding the problems arising fromsand and gravel extraction and invited EC NATURE to examine the existing advice byICES (e.g. Code of Practice) and to elaborate a draft HELCOM Recommendation on theissue, as appropriate (EC 7/96, document 15/1, paragraph 7.22).

The present paper aims at a compilation of background information on occurrence anddistribution of sand and gravel resources in the Saltie Sea and the current and expected


I'I '

I 'I

exploitation activities. Furthermore, an overview on possible environmentar implicationsis given.

This information can form the basis for conclusions, especially concerning the need foraction.

For the elaboration of this document the work already done by ICES, other studies andreferenees concerning the item, as weil as information submitted by the Contracting Parties has been evaluated.

2. Legal regulations for marine sediment extractionIn all Saltie Sea Countries the extraction of marine sediments needs apermission tromnational authorities.

In Sweden an Environmental Impact Assessment (EIA) for marine mineral extractionprojects has been introduced already in 1987 by the Act (1987 : 12) on the Managementof Natural Resources.

In Denmark an EIA is an integrated and obligatory part of the Iicensing process. According to The Raw Materials Act exploration and extraction of raw materials in territorialwaters and on the continental shelf may take place only in geographically demarcatedareas which have been subject to environmental assessment, and subject to apermittrom the Minister tor Environment and Energy.

I

In Finland sand and gravel extraction does not require obligatory EIA. However, the extraction of mineral resources trom marine areas requires apermission trom the appropriate Water Court. The Court has to weigh the economic and other profits with the impacts on the marine environment As a result, the permission can be granted or denied.In order to be able to weigh the different interests the Water Court often demands assessment of impacts on fishery and marine environment.

In the EU member states the "Directive on the Environmental Impact Assessment torcertain public and private projects" (85/337/EEC) from 27/6/1985 also applies to the extraction of minerals trom the seabed. Mineral extraction is included in annex 11 of the Directive1. For projects according to annex 11 an Environmental Impact Assessment has tobe performed if the member states take the view that an EIA is required due to the character of the project. It is within the discretion of the member states to define criteriaand/or threshold values concerning EIA requirement.

In Germany, e.g., such threshold values are defined by the "Decree about EnvironmentalImpact Assessment for mining projects" trom 13/7/1990. According to this decree an EIAis 'obligatory if the extraction area exceeds 10 hectares or it the daily exploitation is morethan 3.000 tons.

'The Directive 85/337/EEC has been amended by the Directive 97/11/EC from 3/3/97. Themember states are obliged to implement the new regulations into national legislation until14/3/1999. In the new Directive the extraction of minerals from the seabed still betongs to theannex 11 projects. For these projects the member states may decide upon EIA requirementon the basis of an individual project study or defined threshold values or criteria. The newlyintroduced annex 111 of the Directive gives special criteria for the decision if an EtA is required or not.

•


In Denmark an EU-Environmental Impact Assessment, during which the general public,·public authorities and organisations have the opportunity to state their opinion, should becarried out "on top" of the obligatory'environmental impact assessment, if the appliedextraction activity can be assumed to have cl significant impact on the environment.

Since Finland has joined the EU in 1995 the regulations of the EIA Directive will be implemented into Finnish legislation.

In some non-EU states like Poland and Estonia an Environmental Impact Assessmentalso is required for marine sediment extraction projects.

3. Marine sand and gravel resourees in the Saltie SeaDenmark

The Danish marine areas, including the North Sea, the Kattegat and the Saltic Sea, arevery rich in mineral resources like sand, gravel and stones, which are exploited at a considerable rate.

Marine resources of fine sand in the North Sea and Saltic Sea are several billion m3 • However, the resources are not equally distributed and environmental constraints may seriously limit the reserves in some areas. It is expected that indicated reserves are available for at least 50 years in most areas.

Resources of medium and coarse sand are limited in volume and distribution. Most ofthe accessible resources are located in shallow waters and are smalI, complicated instructure, and therefore difficult to exploit. A few larger resources have recently beenidentified in deeper waters and are expected to produce the majority of marine mediumand coarse sand in the next 25 years.

Gravel (6 - 200 mm) is a finite resource dredged in a limited number of areas primarilylocated in coastal shallow areas of highly environmentally vulnerability, where promisingresources have been identified. Presently, the total reserves have not been evaluated.Sased on reconnaissance surveys a number of inferred resources have been found inthe North Sea and the Saltic.

Germany (Schleswig-Holstein)

There are various deposits of sand and gravel on the coastal shelf of Schieswig-Holstein.

Germany (Mecklenburg-Vorpommern)

The marine deposits of sand and gravel on the coastal shelf of Mecklenburg-Vorpommern are currently estimated to amount about 60 million tons. The thickness of the sandand gravel layers is rather low, in the average only about 1 m. The economically interesting deposits 'are mainly situated between the 6 and 20 m depth line (Krause et al.,1996, Gosselck et al., 1996).


I·

Tab. 1: Prospected areas on the continental shelf of Mecklenburg-Vorponimern (UWG1993) .

location sediment type estimated remarks.,amount

(million tons)(1) outer Wismar sandy gravel. sand 5,4 obviously severe conflicts with natureBight conservation aims

(2) sea area of Küh- sandy gravel. gravel 7.0 sediment layers of 0,2 - 2,5 m thick-lungsborn ness, total area 218 ha

(3) sea area of sandy gravel. sand 6,9Markgrafenheide

(4) Plantagenet- sandy gravel. gravel 9.1 shoal about 22 km NE DarßlZingstqrund peninsula, water depth < 8 m

(5) sea area north of sandy gravel, sand. ? only partly prospected. extraction diffi-Rügen pebbles cult because of pebble and boulder

lavers

(6) Tramper Wiek sandy gravel, sand 4.1

(7) Landtief/Osttief sandy gravel, sand 2,4 areas near to the Rügen - Usedom sill(Boddenrandschwelle). sediment lay-ers of 0.1 - 0,8 m

(8) Greifswalder sandy gravel 3,1 108 ha, average thickness of the se-Bodden diments 1.9 m; conflicts of exploitation

I with nature conservation aims (Speci-al Protected Area according to EUBird Directive)

(9) sea area off sandy gravel, sand 4,7 3 prospected areas, predominantlyUsedom thin sediment layers of 0,2 - 0,3 m

(10) Adlergrund sandy gravel, sand >20

total amount > 62.7.

Po/and

There are many prospective areas of raw materials in the coastal waters of Poland. However. most of them may be potentially only because they are poorly documented. Thedeposits are mainly stretching along the coastline, but there are also some deposits onthe Slupsk Bank, on the Southern Middle Bank, at Gdansk Bay and Odra Bank. Thesurface of the aggregate beds is locally covered with sand of 0,5 m thickness.

Russia (Kaliningrad region)

Bottom deposits of sand and gravel are widely spread on the Sambian-Curonian plateau. The most important of them are situated near to former accumulation zones of different stages of the post-glacial Baltic Sea history. One of the most prospective sites isthe massive of ancient dunes, situated in the vicinity of the oil drilling installation (0-6,see map), which covers an area of about 90 km2

• The sand resources of this siteamounts to not less than 300.000 m3

• (1, see figure)

Another area interesting for exploitation is situated in the region of the bore hole 0-6-5/1.This area is covered by an about 10m thick layer of ancient marine sands of medium

•

lCES-WGEXT 94 ;tpri11998

.,,'~:. .....:~; ...-, '~~..

., .

grain size, and an upper layer of 1 - 2 m of sand - gravel. (2)

A vast field of medium grained sands is situated in the Sambian depression. These thickcumulative strata (up to 10 :12 m) iridude shifting sands (aleurites, 0,01 - 0,1 mm) andpeat layers. According to preliminary calculations the sand resources accumulated onthis site amount more than 1 million m3

• (3)

A further sand deposit is scattered by paleogenian basic rocks. It mainly consists of sandof different grain size. The basic rocks at this site take up to 40 % of the whole paleogenian exposures of the Kaliningrad coastal waters. They are exposed at the bottom orcovered by a thin layer (1 - 2 m) of sediments. The reserves of these sands are estimated to be several million m3

• (4)

Gravel deposits are usually represented by thin (Iess than 1 m) lenses which are situatednear former coastal banks, foots and slopes on abraded terraces. The thickness of gravel areas on slopes of abraded and polygenetic terraces occasionally may exceed 5 m.

The south-eastern part of the Vistula lagoon harbours considerable reserves of glacialsand and gravel, which are torming mobile ridges. These ridges are the marine continuation of the exploited terrestrial deposits. (5)

Lithuania and Latvia

Marine sand and gravel deposits are situated also in Lithuanian and Latvian coastal waters.

Estonia

There are 4 proved deposits of sand and gravel which could be of interest for exploitation in the coastal waters of Estonia (Hiiumadala, Naissaare, Prangli, Ihasalu).

Russia (St. Petersburg region)

The Gulf of Finland harbours considerable marine sand and gravel deposits.

Finland

There are considerable sand and gravel resources which could be of interest for exploitation in the coastal waters of Finland. Investigations are going on.

Sweden

The usable sand and gravel fields are mainly situated at the south-west Saltic Sea coastof Sweden.

4. Exploitation of marine sediment resourees in the Saltie Sea states

Denmark

The· extraction of marine sand and gravel in Denmark represent 10-13 % of the total production of materials tor construction and reclamation.

The dredging of sand fill for land reclamation and beach nourishment has increased overthe last 10 years caused by several large construction works in coastal areas and a


change in approach to coastal protection. In 1996, the majority of the sand fill (3 mio. m3)

has been used for beach nourishment projects on the West Coast of Jutland.

Tab. 2: Marine sediment extraction in Denmark 1990-1996

Year Sand Gravel Gravel Sand fill Mise.0-2mm 0-20 mm Stones (TiII)

6-300 mm

·1990 1.0 mio. m3 0.2 mio m3 0.6 mio m3 3.9 mio m3 0.1 mio m3

1991 1.1 mio. m3 0.5 mio m3 0.9 mio m3 4.4 mio m3 1.0 mio in3

: 1992 0.7 mio. m3 0.5 mio m3 0.9 mio m3 1.2 mio m3 0.8 mio m3

·1993 0.9 mio. m3 0.2mio. m3 1.1 mio. m3 2.1 mio m3

.1994 1.1 mio. m3 0.2mio. m3 1.3 mio. m3 2.6 mio. m3

I 1995 1.1 mio. m3 0.2mio. m3 1.2 mio. m3 2.8 mio. m3 0.3 mio. m3

1996 0.9 mio. m3 0.2 mio. m3 1.1 mio. m3 4.1 mio. m3 2.2 mio. m3•

For many years, fossil shells have been dredged from three areas in Roskilde Fjord. Thisactivity was for environmental reasons stopped by the end of 1997.

In 1996 the dredging in the Baltic Sea, including Kattegat, amounted to about 40 % ofthe total dredging in Denmark and took place from 151 permitted areas. Most of the areas are located around Sjrelland and Fyn. In general all areas are loeated at waterdepthsover 6 meter and outside proteeted areas like Ramsar- and EU-Birdprotected Areas orar~as proteeted by The Nature Conservation Aet.

The dredging of aggregates for construction was about 1,9 mio. m3 of whieh 0,4 mio. m3

was exported to Germany and Sweden. In 1996 0,5 mio. m3 of sand fill was dredged forthe construction of the fixed link between Denmark and Sweden.

Germany (Schleswig-Holstein) . eNo extraetion of marine sand and gravel resourees has taken plaee during the last 10years on the coastal shelf of Schieswig-Hoistein, and no extraetion is currently plarined.

Germany (Mecklenburg-Vorporri~ern)

On the eoastal shelf of Meeklenburg-Vorpommem there are aetually 17 extraction fieldsfar whieh permission has been granted by national authorities. The majority of the extraetion sites· are used for eoastal defenee purposes. These sites are not permanenUyexploited but only temporarily, if there are coastal defence projects executed in the respeetive region. From four fields the sand and gravel is used. as construction material(eonerete produetion, filling material, road eonstruetion ete.). These fields are: sea areaoff Kühlungsbom, Greifswalder Bodden, Adlergrund, Plantagenetgrund.

The total area of permitted extraetion fields amounts 200 ha. The total exploitation was1.263.316 t in 1995 (about 1 million tons construetion material, the rest for coastal derencfi purposes) and about 2 million tons in 1996 respectively (1 million tons constructionmaterial, 1 million tons for eoastal defence installations).

/CES-WGEXT 96 L1pril/998

•

Poland

.Gf1J.Vß/: No large scale exploitation was carried· out in Polish marine areas neither in thepast nor is expected in the next future. Test extraction has been carried out in the SlupskBank area during the years 1985 - 1989. with about 1,4 million t of sand and gravel being removed. Some test extractions have been carried out also on the Southern MiddleBank and Koszalin Bay during the period 1987 - 1989. but only small amounts of sediments have been extracted (about 4.000 - 6.000 t from each site).

Licences for extraction of gravel have been issued for two areas. but exploitation is notexpected in the next few years.

Sand: Sand is extracted in Poland for coastal defence purposes only. i.e. replenishmentof beaches and dunes.

At the north-east of Cape Rozewie a 5 km2 area is designated for sand extraction for theneeds of artificial beach nourishmen1. It is exploited since 1995 at a rate of 100.000m3/year. A 1 km2 sand extraction field 5 km north of Jurata on Hel Peninsula was used in1993 and 1995 for beach replenishment purposes. the total amount of extracted sandbeing ca. 200.000 m3

•

In the past (1989-1992) sand was extracted at 4 sites in the Puck Bay for coastal defence measures on Hel Peninsula. In 1993 two sites have been c1osed. From the remainingtwo sites sand is presently extracted at a rate of 150 - 300.000 m3/year. but this shall bestopped in 1998 (except in case of emergency situations). The total amount of sand extracted from the Puck Bay is about 6 million m3

• Extraction of sand regularly takes placefrom approach channels to ports and from sand traps in relation to operation of artificialsand by-pass systems at ports. The annual amount of this sediment removal is about60.000 m3 at the port of Kolobrzeg. 80.000 m3 at the port of Darlowo. 80.000 m3 at Ustkat 30.000 m3 at Leba and 200.000 at Wladyslawowo.

Russia (Kaliningrad Region)

There is no actual exploitation of marine sand and gravel resources in the Kaliningradregion of Russia. and no industrial exploitation is expected in the near future. However•investigation of marine mineral resources is undertaken and exploitation can be expe'cted in a long term run if the economy recovers.

There are actual plans for the construction of an artificial island for oil exploitation purposes. A total area of 67 ha will be required for the construction of the island and extractionof building material. The duration of the work is expected to be one vegetation season.The recovery time of marine fauna in the extraction area is expected to be about 5 years.

Lithuania, Latvia and Estonia .

There is no actual exploitation of marine sand and gravel resources in Lithuania. Latviaand Estonia. and no exploitation is expected in the next future.

Russia (St. Petersburg region)

In the S1. Petersburg region of Russia sand and gravel resources are exploited on three


extraction fields. The annual extraction rate of all ttlree fields amounts about 1,2 millionm3

• The fields are: Styrsuddensky Bank (800.000 m3); south of the B. Beresow Island

(200.000 m3) and south of the Seskar Island (200.000 m3).

Finland

Since the extraction of sand and gravel on terrestrial areas was regulated in 1982 theextraction from marine areas has increased considerably during recent years, and canbe expected to increase further in the future.

The material is mainly used as construction and filling material in harbour works, roadconstruction and other projects in the coastal zone. A total extraction of 17 million m3 hasbeen planned for the period 1990-1997 in the three main areas: Helsinki, Kotka, and theland bridge to Hailuoto Island. The city of Kotka has extracted about 2,5 million m3 ofsand and gravel for harbour facility expansion. For the city of Helsinki apermit for 5 million m3 has been issued for landfill projects (housing scheme, harbour facilities) (ICES1992). _

Sweden

Marine sand and gravel extraction from the Swedish part of the Baltic Sea, mainly thesound, started in the beginning of the century. In 1966 the extraction was regulated bythe Act (1966: 314) on the Continental Shelf.

During the period 1966-1992 exploitation took place on 13 extraction sites. The amountof,extracted material was 12.937.282 m3 in the period 1966-1978 and 1.711.363 m3 inthe period 1979-1992. .

The gained material has mainly,been used as construction material (Iandfills), but also,regarding one site (V-Haken), as industrial mineral for glass manufacturing.

In 1992 sand and gravel extraction was stopped for environmental reasons.

5. Environmental impacts of marine sand arid gravel extraction

The two methods most commonly practised in aggregate extraction are anchor hopperdredging and trailer suction hopper dredging. In the former, the dredger anchors over thedeposit and mines it by forward suction through a pipe (fig. 1a). Large pits are thus formed on the sea floor, up to 10m in depth and 10-50 m in diameter (Hygum 1993, p.18). Most aggregate dredging in Denmark is conducted by this methode Trailer dredgers,in contrast, extract the deposit by backward suction through one or two pipes whilst underway, thereby forming shallow furrows on the sea flool- (fig. 1b). These are generally20 - 30 cm deep and up to 2 m broad.

In· both cases the aggregate and water are piped aboard to the ships hopper. As thehopper fills, the aggregate displaces the water, which overflows back to the sea, carryingwith it suspended fine material wtlich forms a turbidity plume. On some dredgers, screening of the aggregate is carried out and excess sand or pebbles are returned to the seabed to maintain a specific sand to pebble ratio in the cargo (ICES 1992).

Th'e physical and chemical impacts resulting fram these activities are:

I. 'substrate removal and alteration of the sediment composition and the boUom topography

lCES-WGEXT 98 ~tpri11998

.~" ... '." .. "'.....' .......;~~"'''., ....;...... : ....... :.~...

11. alteration of the hydrographical situation

111. formation of turbidity plumes and resuspension of chemical substances

IV. sedimentation of"s'~~p~nde(r~~t~ri~I:-'oversanding and other problems relatedto screening, including resuspension of the newly sedimented material

5.1 Impacts of substrate removal and alteration of sediment composition and bottom topography

The most obvious impact of sand and gravel extraction is the removal of the substrateand the resulting destruction of its infaunal and epifaunal biota.

The boUom topography is changed and the character of sediments may be temporarilyor permanently altered. The severity and duration of these impacts depend on extractiontechnology, hydrographical situation, sedimentation figures and other parameters at theextraction site. They may differ considerably.

Infill of the pits and furrows is dependent upon the exposition, Le. the ability of bottomcurrents to move surrounding sediments, and the availability of movable sediments inthe vicinity of the extraction site. Except in areas of mobile sand this tends to take a rather long time span: For example, according to observations of van der Veer et al. (1985,cl. ICES 1992) in the Dutch Wadden Sea, pits in tidal channels were filled within oneyear, those situated in tidal watersheds took five to ten years, and those dug in tidal flatareas were still visible after fifteen years.

Recovery time of benthic fauna may vary from one month to fifteen years or even more,depending upon the intensity and duration of changes of environmental parameters andsediment character, stock of colonizing species and the immigration distance (Krause etal. 1996; ICES 1992). If the character of sediments is not altered by the extraction, reestablishment of the former biocoenoses normally takes place within a time span of afew months to 5 years after the end of the mechanical disturbances (Hygum 1993). If thecharacter of the sediment is altered to a more soft sediment type, the original hard bottom community will change to a soft bottom community (COWINKI, 1992). No hydrodynamic processes are known to concentrate gravel and stones at the seabottom (Aagaard, 1991). The possibility of recovery is therefore reduced. Recolonization time depends on physical factors Iike depth, exposure (waves, currents), sedimentation characters etc. In areas with low depth and strong exposure normally it is faster, in areas withlow exposure it may last for a rather long time. According to investigations of Rhoads &Germano (1982) and van der Veer. et al. (1985) the re-establishment of the original coenoses in "Iow energy areas" may take up to 10 years (cl. Krause et al. 1996).

In the Baltic Sea the recovery of benthic fauna has been monitored on the Slupsk Bank(Poland) and in the sea area off Kotka (Finland). In both cases an examination of themacrobenthos at the dredging site indicated that the total number of taxa had returned tothe pre-dredging value within one year. However, abundance and biomass still remainedlow, suggesting that complete recovery of the community would need several years(ICES 1997). .

The extraction of 50.000 t of marine sediments at the eastern Scottish coast resulted in adeepening of the bottom of 30 cm, but not in an alteration of sediment quality. Sevenmonths after the extraction many of the original taxa already had resettled on the affec-


ted area (Kenny and Rees 1994). However, whilst the dominant species recolonizedquickly following dredging many rarer species did not. 24 month after dredging the biomass was still substantially reduced. This was thought to be due to a local increase insediment disturbance caused by tides and waves. Evidence from side scan sonar records and underwater cameras indicated a considerable sediment transport during thefirst two winters following dredging resulting in an infill of the once well-defined dredgetra~ks (Kenny & Rees 1996).

Alterations of the benthic communities are observed in areas where the sediment character is altered by the extraction process. The affected area will be recolonized by macrozoofauna communities which are different to the original ones. If the original sedimenttype is not re-established by transport processes the changes of fauna composition willbe permanent. In many cases the coenoses change towards soft bottom communities(Hygum 1993). Such alteration of fauna composition, e.g. has been observed after acommercial sediment extraction in the Dover street. The topography in the extractionarea was altered, the extraction had forrried furrows in the boUom which were filled bysedimentation with finer sediments than the original ones. The benthic communities of •these areas changed from coarse- to fine sand communities (Desprez 1992). Infilling ofdredged pits with sediment finer than the original one or the surrounding substrate andsubsequent alteration of the coenoses has been noted in several cases by a number ofauthors (ICES 1992). However, in some cases also permanent changes from soft tohard bottom communities may occur. One example is reported from the Seine Bay.When sand and gravel overlying a rocky substrate were removed, no deposition of sediments on the pebbly and rocky ground occurred and, as a result, a hard boUom faunadeveloped (ICES 1992).

Permanent alterations of sediments and, as a consequence, of benthic communiiies aresupposed by Krause et al. (1996)' and Gosselck et al. (1996) if the rather thin sedimentlayers dominating on the coastal shelf of Mecklenburg-Vorpommern areexploited. Thesand and gravel layers of the pote'ntial extraction sites have a thickness of between 0,35and 2,7 m (UWG 1993). These sediments are of glacial origin. Re-establishment of theoriginal sediment character after extraction therefore can not be expected. In some are-as refilling will take place with fine sediments, in other sites mari will become exposed.Species rich sand boUom coenoses will change to species poor mari bottom fauna. The eextraction of thin sediment layers can be expected to affect rather large areas. This gi-ves reason to assurne severe ecological effects for the marine ecosystem, if not an adequate layer of the original sediments remains on the bottom, which allows recovery ofthe coenoses.

In Denmark the stone reefs, formed by residual glacial deposits of boulders, stones, pebbles, and gravel, are of special concern. Biologically these reefs are very valuable sincethey are representing the only natural substrate for hard boUom communities of marinebenthic flora and fauna. The development of the biological communities depends on thecomposition of the bottom sediment being either dense boulders, mixed boulders andsmaller stones or pebbles and gravel.,Localities with a patchy bottom consisting cf areascovered with big boulders and gravely areas have the highest biodiversity. Marine aggregate extraction on stone reefs may include the reduction of hard bottom area, an alteration cf the sediment character towards softer sediments and/or a decrease in the diversity of geological and biological structures (Ministry for Environment and Energy Denmark 1997).


The effects of different extraction methods on sediment character and recovery of benthic fauna were studied by Norden Andersen et al. (1992). From July 1987 to March1988, three million m3 of sand were dredged in a depth of 12 - 16 m of Koge Say, Denmark. Dredging was performed as weil by stationary suction as by trailing suction. Thefirst method left up to 10m deep pits in the bottom, while trailing suction removed up to 2m of the sea bed, leaving a pattern of 1,5 m wide and up to 0,5 m deep furrows on thebottom. About 17 month later in the trailing suction areas annual benthic faunal specieshad largely recovered, whereas the larger perennial species were stilllow in biomass. Inthe pits formed by stationary suction at a depth of more than 7 m below the natural seabottom a dense layer of detrital matter and plant debris had brought about anoxic conditions. Recovery of macrofauna thus not was possible. Oxygen depletion at the bottom ofdepressions caused by sediment extraction is also reported by other authors (ICES1992).

Recovery time of benthic communities does not only depend on intensity, character andduration of mechanical seabed alterations but also on the species composition. Communities of short-living species or species with a high reproduction rate in general may recover more rapidly than communities of slow growing, long-living spedes. Representatives of the latter groups are, inter alia, the bivalves Aretiea islandiea, Astarle spec. andMaeoma ealearea. Sut also the communities of the bivalves Mya arenaria, Maeoma balthiea and Cerastoderma spec. need 4 - 7 years until the natural size and age distributionof the population has re-established.

Macrophyte stands and sand and gravel extraction may coincide in some regions of theSallic Sea. Macrophytes may occur up to a depth of 20 m, if the water transparency isappropriate (Schramm 1996). Schwenke (1996) even assurnes macrophyte occurrencesup to a depth of 30 m. However, during the last decades a massive decline of macrophytes has been observed, resulting in shifting of the distribution border towards lower waterdepths. Eutrophication, increased plankton growth and, as a consequence, reduced lightpenetration are considered to be the main reasons. Due to the already naturally restricted distribution on the coastal shelf and the overall decline in the Sallic Sea macrophytestands are generally of high conservation value. Knowledge about recolonization of macrophytes after mechanical destruction by dredging is rather poor.

Senthic organisms are the feeding base of waterfowl (especially sea ducks) and fish.Temporary destruction of the zoobenthos and/or permanent alteration of the compositionof benthic communities as a consequence of sediment extraction may change feedingconditions for species of the higher level of the trophic chain. Gosselck et al. (1996), e.g.suggest possible impacts on resting or wintering conditions for seaducks if sand and gravel extraction took place on the most favourable feeding grounds of the birds, like theexposed sand bares of the outer Wismar Sight, Hannibal and Lieps.

Fish stocks may be seriously affected by the dredging process where spawning groundscoincide with the deposit. One example is that of the herring, certain groups of whichspawn on stony substrates influenced by bottom currents. SandeeIs and edible crabmay be similarly affected (ICES 1992). In the Sallic Sea, e.g. the surface of the sand andgravel deposits of the Vistula lagoon (Russia, Kaliningrad region) is a spawning groundof zander, bream, roach, perch, herring and other fish. If the sand and gravel resourceswere exploited fish reproduction in the lagoon would be impaired.


Avoidance behaviour of fish as a consequence of sediment plume is a weUdocumentedreality.

Fisheries practice may be impaired by the. uneven sea bottom topography created byaggregate extraction, which may destroy bottom trawls and other fishery devices.

5.2 Impacts by alteration of the hydrographical situation

The alteration of bottom topography may cause changes in the hydrographical situationand thereby affect water exchange or sediment transport.

Gosselek et al. (1996) and ICES (1992) emphasize possible effects on coastal erosiondue to alteration of wave and current patterns if aggregate extraction is executed in shallow coastal waters. In this connection possible effects on coastal proteetion have to beconsidered, either by interference with the supply of sand and gravel to the beach or byreducing offshore wave proteetion and thereby changing the wave energy and/or direction reaching the coast.

According to Gosselck et al. (1996) distinct effects can be assumed if sediments are taken from shallow submarine sills. Such sills, e.g. are forming typical barriers betweenshallow lagoons arid bays and the open Baltic Sea, as it is the case with Wismar Bightand Greifswalder Bodden (Germany, Mecklenburg-Vorpommern). They are key elements for controlling the water exchange betWeen the lagoons and the Baltic Sea. If material is extracted from the sills, water exchange may be facilitated. Depending on thespecial conditions of the respective area, this may have considerable ecological effects.Gosselek et al. (1996) assurne, that for instance sand and gravel extraction on Hannibaland Lieps (the sills separating the Wismar Bight from the Mecklenburg Bay) may facilitate the entrance of anoxie bottom water from the Mecklenburg Bay into the Wismar Bight,resulting in severe effects on benthic communities and fish.

5.3 Impacts by sediment spill, turbidity plumes and resuspension of chemical sub-stances .

The amount of spill, dispersion and sedimentation patterns of suspended material de- •pend on the composition of the dredged material, the dredging and transport equipment,the reclamation process and hydrographical factors. Suspension of particles and increa-se· in water turbidity is caused as weil by the dredging process on the bottom as by theoverflow water from the hopper. Loading of transport vessels, transport and the reclama-tion process also may cause spill.

In general, sediment spreading from the draghead is Iimited compared to the amount ofsediment released with the overflow. The spill caused by transport normally can be corisidered negligible, but the overflow during filling of transport vessels may contain considerable amounts of suspended material (Nielsen 1997).

According to Danish records the overflow wate.. of the hopper may contain between 2and 10 % of the dredged material (Hygum 1993). Nielsen (1997) reports spill percentages between 0,5 and.25 % of the dredged material, depending on aggregate type anddredging technology.

The influence of dredging technology was demonstrated by ci spill monitoring during theextraction of sediments at Kriegers Flak (Denmark) for the construction of the Oeresund

leES - lrGEXT 102 itprill998

... '\ ,., rOH -'.'"

bridge. There were clear differences between both vessels used, tlle average spill percentages amounting 2,62 % and 1,26 % respectively (Water Consult 1997). To someextent it is possible to reduce the ar:nount of spill by adjusting the pumping and sailingspeed. Technical optimization of the pumping system, ships hopper, entrance and outletsystem also makes it possible to reduce spill. For the dredging of very fine-grain sediments (clay, silt, mari) special equipment has to be used which is capable to retain suchfine partides.

The magnitude of the turbidity plume depends on the mud and silt content of the aggregate and the natural water turbidity. In high energy areas close to the eroding coastlinenormally few problems can be assumed from the extraction-related turbidity since thenatural background level is already quite high (ICES 1992). In .Iow energy areas the elevation of turbidity caused by dredging activities may be more distinct and last for a langertime (up to several days), especially if the aggregates contain fines or if they are coveredby mud or silt layers. Eight- to fourhundred-fold increases in turbidity have been observed in connection with dredging activities (Hygum 1993, ICES 1992).

The duration and expansion of turbidity plumes depend on factors such as water temperature, salinity, Gurrent speed, and size range of the suspended material. At one extraction site, the extension of the turbidity plume may be different between the surface water,the water column and the bottom water. Such records are, inter alia, reported by Bohlenet al. (1979) from the Thames estuary: In the surface water the turbidity plume reached

. up to a distance of 300 m, whereas in the water column and at the bottom no elevatedconcentrations of suspended material was observed only at a distance of 700 m (cl. Hygum 1993).

Although elevated turbidities may be recorded up to distances of several hundred metersfrom the hopper, in special cases even several kilometres, normally the concentration ofsuspended material decreases rapidly with increasing distance. Kioboe & Mohlenberg(1981, cl. Hygum 1993) recorded concentrations of 3 - 5.000 mg/l dose to the hopper,but concentrations of more than 100 mg/l were restricted to a radius of about 150 m. At adistance of 650 m the concentration was 10 mg/l in the bottom water, and 1.000 m fromthe hopper no elevation of turbidity was observed.

e The resuspension of sediments in relation to dredging activities may cause alterations ofchemical parameters, like release of nutrients, heavy metals or other compounds to thewater phase. Also decrease of oxygen is a possible effect, if organic compounds are released. According to reports from dredging activities in the Belt Sea the concentration ofinorganic nitrogen and phosphorus may be elevated in the overflow water 3 to 100 fold(Hygum 1993). Considerable elevation of nitrogen and phosphorus in the vicinity of thehopper also is reported from the United States and from the Thames estuary. Release ofheavy metals was observed in some cases (Hygum 1993).

Measurements of nutrients and heavy metals in the turbidity plume done by Tramontano& Bohlen (1984, cl. Hygum1993) demonstrated elevated values of nutrients up to 180 mbehind the hopper, the highest concentrations being recorded within the first 50 m. Anincrease of heavy metals (Mn and Cu) was proved up to a distance of 12 m.

In general, the chemical effects are however likely to be minor due to the very low 0

rganic and clay mineral content of the sediments. Also, dredging operations are generally of Iimited spatial extent and short duration, which further limits the chemical impact


(ICES 1992).

The elevated concentration of particles in tile water means a threat for tile vegetation onthe seabed, which may be shaded. or covered by sedif!lented particles. The food supplyof seabirds may be affected, and the migration of certain fish species may be disturbed(ICES 1992).

Short time exposure with suspended material seems not to be harmful to adult musseisand fish. Filter feeding musseis may even show higher growth rates. However. eggs andlarvae of the species in general are more susceptible. In laboratory tests it was demonstrated that some fish species (e.g. visual feeders like mackerel or turbot) avoid concentrations of suspended material of more than 10 mg/I. The feeding of herring larvae is impaired at concentrations of only some mgll of suspended material (ICES 1992, Hygum1993). Other fish species may be attracted by the nodour stream" of the crushed benthos. Similarly. primary production within the water column may be either increased ordecreased depending upon the ability of plankton to deal with the increase in nutrientsand other suspended material and the decrease of light penetration (ICES 1992). •

However. although the concentration of suspended material caused by dredging mayreach magnitudes which are harmful to organisms, normally such concentrations arereduced rather quickly by dilution effects of currents and waves.

The release of nutrients as a consequence of dredging activities normally is also assumed to be of minor importance for marine Iife due to its temporarily and spatially restricted occurrence. Same minor effects on primary production are supposed for semi-closedsea areas like fjords, but detailed data are rather scarce (Hygum 1993). Release of heavy metals or other harmful compounds is assumed to be a minor problem, except if extraction takes place on former dumping sites (Hygum 1993).

Decrease of oxygen as a consequence of resuspension of oxygen consuming substances may be a problem if the deposit is covered by mud and silt layers. This is the case,inter alia, with deposits situated in internal waters like the Greifswalder Bodden (Germany) or Vistula Lagoon (Poland/Russia).

5.4 Impacts by sedimentation of suspended material and oversimding, including eresuspension of the newly sedimented material

Redeposition of spill sediments predominantly will take place within the dredging area,but will also extend beyond it, depending on current strength, waves, salinity and watertemperature. Concerning the sediment extraction at Kriegers Flak (Denmark) it was estimated that with the predominant flow velocities (0,1 m/s) 99,9 % of the spill will settleclose to the reclamation area and only a small proportion of very fine material « 0,063mm) will be carried away and scattered over a larger area.

However, the dispersion figure of particles strongly depends on the content of fine material and the hydrographical situation, especially sea currents and waves. The appearance' of suspended material occasionally can be recorded at distances of up to 1.000 mfrom the extraction site. Once settled on the sea floor, the sediment will still be liable toresuspension or transport. However, information on the behaviour and dynamic of sedimented fines is still scarce, and it is not clear yet if sedimentation of suspended materialis rather a short-term effect of a few hours or days, or a long-term effect lasting severalmonth or years (Hygum 1993). Results of Kenny and Rees (1996) indicate that sedi-


., .,. -.11', ~ ~ ". •

ments once disturbed by dredging activities are easier moved by tides and waves. Suchdredging-induced increase in sediment mobility also may cause oversanding of benthicorganisms and reduce their development and biomass.

The practice of screening out sand directly back to the sea floor may significantly alterthe substrate and create mobile sand areas on the former gravel banks.

The effects of sediment fallout on benthic communities outside the extraction area maybe quite different. Following possibilities have been recorded (ICES 1992):

a) defaunation within the affected area is initially virtually complete, similar to that in thedredging area, but recolonization progresses more rapidly

b) defaunation is less pronounced than in the dredging area and recolonization is morerapid

c) species diversity and abundance is enhanced in the area of sediment fallout

• d) the effect is negligible

Thus, the impact of sedimentation upon the benthic ecosystem is normally not as severe as that of the direct substrate removal (ICES 1992). The prime risk of redepositionof fines or screened sand are the smothering of fish eggs on spawning grounds, like herring and sandeei, and the suffocation of filter-feeding sessile benthos such as musseisand polychaets. In addition, shellfish such as lobsters may lose habitats through siltingup ·of crevices in which they live, and edible crabs which become torpid while broodingmay be especially susceptible to smothering and suffocation by sediment fallout (ICES1992).

Laboratory te~ts have shown that already a slight covering with sediments may reducethe hatching success of herring eggs and the colonization success of mussei larvae (Hygum 1993).

•6. Conclusions

Marine sand and gravel resources are widely distributed in the Saltic Sea area. They areexploited at considerable rates in Denmark, Germany, Finland and the St. Petersburgregion of Russia. Poland has used marine sand and gravel in the past to a comparablesmall extent. Sweden has stopped exploitation in 1992 for environmental reasons. In theother countries like Lithuania, Latvia, Estonia and the Kaliningrad region of Russia exploitation of marine sediments might become significant in the future, when economy willrecover.

Marine sand and gravel resources are mainly used as construction and filling materialand for coastal defence purposes (beach replenishment).

Extraction of marine sand and gravel resources may cause considerable impacts to themarine environment and fish stocks. Especially benthic marine flora and· fauna is destroyed at the extraction site and may be affected by dispersion and sedimentation ofsuspended material also beyond the extraction area. The recolonization of dredging sites needs several month to some years. Although recolonization in some cases may berather quick the re-establishment of the original age distribution and biomass of the communities normally needs a longer time span of several years. In some cases, if boUom

lCES-lrGEXT 105 April 1998

II'

substrate or character is irreversibly altered, the original flora and fauna not can reeover.

If ~ediment extraction affeets struetures with high signifieance for hydrographical conditions (e.g. submarine sills, banks, spits and near coastal shallow water areas), long lasting or even irreversible effects'on water exchange and coastal sediment dynamics canbe assumed. Such alterations may affect ecological conditions far beyond the extractionarea. They mayaiso have eonsiderable economical consequences for fisheries and coastal defence. They therefore have to be eonsidered especially earefully.

,Alteration of chemical water parameters like increase of turbidity, release of nutrients,heavy metals and other harmful compounds or oxygen eonsuming substances is a regu-lar side effect of the dredging process. Although these effects also may harm marine lifethey seem to have a rather temporary character. After termination of the eXtraction process the ehemical parameters of the water body return rapidly to the pre-dredging stage.

Taking into account the possible impacts on marine life and the marine ecosystem, forsand and gravel extraction projects in the Baltic Sea the following principles should be ..applied: _

General

Decisions of national authorities on permits for marine sediment prospection and extraction shall be based on an adequate 'investigation and evaluation of the natural condilions, the ecological consequences and possible interferences with other legitimate usesofthe sea.

A. Environmentallmpact Assessment

(1) An Environmental Impact Assessinent shall be an obligatory part of the extractionpermission procedure. It shall take into consideration:

a. the amount and type of the sediment being extracted

b. the eomposition of the aggregate (grain size structure, organie eontent, contaminationwith harmful substances etc.) ,

c. the extraction method

d. the species composition arid abundance of benthie flora and fauna at the extractionsite and other areas potentially affected by the extraction process

e. the significance of the extraction for fish, marine mammals and seabirds (spawning,breeding, migration, feeding, resting)

f. :the possible alteration of chemical and physical parameters in the water column andsediments (increase of turbidity, release of nutrients, harmful substanees, oxygen consuming compounds)

g.:the hydrological situation at the extraction site (waves, currents, salinity, water tempe,rature, sills and other structures with significance for hydrologieal proeesses ete.), ineluding its significance for the expansion of the turbidity plume, sedimentation of sus

.pended material and water exchange

h.' the duration of and the parameters for monitoring during the sediment extraction activities and after its termination

i. interference with other legitimate uses such as fishery, coastal defence, recreation


"Ie< , .•. ,' .. '... "',')0 ~"'"

and tourism or possible damage to submarine archaeological sites.

(2) The Environmental Impact Assessment shall also consider effects on the sea boUomand the water column at the extraction site, as weil as outside the extraction area caused, e.g. by turbidity plumes and sedimentation of particles. It shall also consider possible effects caused by transportation of the extracted materials.

(3) The results of the Environmentallmpact Assessment which has formed the basis fort~e decision on the extraction permit should be made available for scientific evaluation.

B. Sensitive Areas

(1) Permits for marine sediment extraction shall not be granted for:

a. Nature reserves

b. National Parks

c. Areas to be included or which are proposed to the European ecological NATURA2000 network according to the EC Habitats and Birds Directives (92/43/EEC and79/409/EEC) except when the procedure of Art. 6 of the Habitats Directive is followed

(2) Permits for marine sediment extraction in other sensitive areas shall only be grantedif a thorough EIA that covers at least point A of this Guidelines is proving that the extraction is not likely to cause significant negative ecological effects or lead to a deteriorationof the area. Such areas are:

a. Baltic Sea Protected Areas (BSPA) according to HELCOM Recommendation 15/5

b. Ramsar sites

c. areas inhabited by communities of long-living threatened invertebrate species (e.g.the bivalves Arctica is/andica, Astarte sp., Macoma calcarea)

d. important spawning areas of fish

e. important feeding grounds for migrating or wintering waterfowl within resting and wintering areas of international importance

f. large areas densely covered with macrophytes (especially such as Fucus, Zostera,Furcellaria)

g. submarine boulder fields on lag deposits [where they represent a rare or particularlyecologically valuable habitat type]

h. areas of permanent upwelling cold water which provide habitat niches for specializedthreatened benthic species

i. submarine sills with significance for the 'water exchange

j. marine areas near to the coast with significance for coastal sediment transport or withprotective function for the coastline (e.g. sand banks, spits and bars).

C. Extraction Practice

lCES-WGEXT 107 A.pri11998

(1) All appropriate measures shall be taken in order to minimize the ecological impactscaused by sediment extraction, and transportation of the extracted material. This includes:

a., the choice of an appropriate extraction method which guarantees minimum negativeimpacts to the marine environment

b. application of the "best available technology" (BAT) and "best environmental practice",(BEP)' '

c. optimization of the extraction process particularly in terms of reduction of the turbidityplume,

(2) Furthermore special seasonal susceptibilities of the affected area (e.g. bird and fishmigration, reproduction period of marine organisms) shall be considered.

(3) The recovery of marine Iife after termination of the extraction process shall be facilitated by appropriate precautionary measures. It shall be ensured that the original surfacesediment type shall remain on the bottom with an adequate thickness for recolonizationby. almost the same benthic organisms assemblage that inhabited the site prior to theextraction.

D.; Environmental Monitoring

M~nitoring shall be a component of ever'j kind of extraction activities.

Dredging vessels should be equipped with monitoring systems for recording the positionarid the amount of extracted sediments.

Spill monitoring shall be carried out, including the parameters

a) amount and composition of spill

b) , dispersion of suspended particles of the turbidity plume

c) , sedimentation pattern

d) I biological parameters (plankton, fish, sea birds etc.), as appropriate.

Depending on the extracted material monitoring mayaiso be necessary for oxygen andnutrients in the spill water, in the water column at the extraction site and in the turbidityplume; if the sediment contains narmful substances and release by the extraction process has to be assumed the monitoring shall also include these parameters.

After termination of the extraction the recovery of benthic communities shall be monitored as defined in the EIA.

Monitoring data should be made available for scientific evaluation.

"7. References

Aagaard, T. 1991: Sandsugning og det fysiske milj". (Extraction of sand and the physical envi, ronment). The Danish National Forest and Nature Agency, The Ministry of Environment and

Energy, DenmarkCOWINKI, 1992: Recovery of soft bottom fauna following dredging activities, with special refe-

•


... ~.

rence to the construction works in the Great Belt

Desprez, M. 1992: Recent research at the marine gravel extraction site of Dieppe, Eastern English Channel; In: ICES Coop. Res. Rep. no. 182, Kopenhagen 1992 S. 75-76. . .

Gosselck, F.; D. Lange; & N. Michelchen 1996: Auswirkungen auf das Ökosystem Ostsee durchden Abbau von Kies und Kiessanden vor der Küste Mecklenburg-Vorpommerns (Effects ofthe extraction of gavel and gravely sands from the coastal shelf of Meckelnburg-Vorpommern on the 8altic Sea ecosystem); study on behalf of the Agency for Environment and Nature Mecklenburg-Vorpommern

Hygum, 8. 1993: Miljoparvirkninger ved rar og sandsugning. Et Iitteraturstudie om de biologiskeeffekter ved rastofindvining i havet. (Environmental effects of gravel and sand suction. Aliterature study on the biological effects of raw material extraction in marine environments.)DMU-Report no. 81 (The Danish Environmental Investigation Agency and the Danish National Forest and Nature Agency)

ICES 1992: Effects of extraction of marine sediments on fisheries, ICES Cooperative ResearchReport no. 182, Copenhagen 1992

ICES 1997: Meeting of the Working Group on the effects of extraction of Marine Sediments onthe Marine Ecosystem, unpubl. meeting documents, Copenhagen 15-18 April 1997

ICES ACME 1993: ACME Report 1993, Chapter 13, "Guidelines for environmental impact assessment of mar!ne aggregates dredging", p. 43

ICES ACME 1994: ACME Report 1994, Chapter 15, "Guidelines for environmental impact assessment of marine aggregates dredging", p. 67-69

ICES ACME 1995: ACME Report 1995, Chapter 15, "Environmental effects monitoring of extraction of marine aggregates, p. 73-76

Krause, J.C., H. v. Nordheim & F. Gosselck 1996: Auswirkungen submariner Kiesgewinnung aufdie benthische Makrofauna in der Ostsee vor Mecklenburg-Vorpommern (Effects of submarine gravel extraction on benthic fauna in the 8altic Sea off Mecklenburg-Vorpommern).German Journal of Hydrography, Supplement 6, 189 - 199

Kenny, A.J. & H.L. Rees 1994: The effects of marine gravel extraction on macrobenthos: earlypost-dredging recolonisation. Mar. Pollut. 8ull. 28, 442-447

Kenny, A.J. & H.L. Rees 1996: The Effects of Marine Gravel Extraction on the Macrobenthos:Results 2 Years Post-Dredging, Mar. Pollut. 8uH 32, 615-622

Ministry for Environment and Energy Denmark 1996: Rastofproduktion i Danmark (Production ofraw materials in Denmark), Copenhagen 1996

Ministry for Environment and Energy Denmark 1997: pers. communication

Ministry for Economy of the State Mecklenburg-Vorpommern 1996: Mining in Mecklenburg-Vorpommern, Annual Report 1995

Nielsen, P.E. 1997: Sediment spill and sedimentation in connection with dredging and construction work in marine environments. Report submitted to the ICES Working Group on the Effects of extraction of Marine Sediments on the Marine Ecosystem, Copenhagen 1997

Norden Andersen, O.G.; P.E. Nielsen & J. Leth 1992: Effects on sea bed, benthic fauna and hydrography of sand dredging in Koge 8ay, Denmark. Proceedings of the 12th 8altic Marine8iologists Symposium, Fredensborg 1992

Schramm, W. 1996: The 8altic Sea and its transition zones. In: Schramm, W. & P.H. Nienhuis(ed.): Marine benthic vegetation: Recent changes and eutrophication; Ecological Studies,Analysis and Synthesis, Springer 8erlin

Schwenke, H 1996: Phytobenthos. In: Reinheimer, G. (ed.): Meereskunde der Ostsee (Oceanography of the Baltic Sea), Springer 8erlin, pp. 163-172

ICES-lrGEXT 109 April 1998

UWG 1993: Studie zu Möglichkeiten der Gewinnung geeigneter Sande für Küstenschutzmaßnahmen des landes Mecklenburg-Vorpommern aus der vorgelagerten Ostsee (Study onpossibilities of exploitation of adequate sand from the Baltic Sea for coastal defence measures of the state Mecklenburg-Vorpommern, Report on behalf of the State Agency for Environment and Natur Rostock

Water Consult 1997: The Fixed Link across Oeresund: Spill monitoring at reclamation of sand atKriegers Flak for use at the Fixed Link accross Oeresund. Report on behalf of the Oeresundskonsortiet

Adresses of Authors

Christof HerrmannAgency for Environment and Nature Mecklenburg-VorpommernWampener Str.0-17498 Neuenkirchen

Jochen Christian KrauseUniversity Rostock .Oepartment of Marine BiologyFreiligrathstr. 7-80-18055 Rostock

Nadja TsoupikovaEpronovskaja, 29-17RUS-236039 Kaliningrad

Kirsten HansenNational Forest and Nature AgencyHaraldsgade 53OK 2100 Copenhagen 0

Revised by:

•* National representatives of the HELCOM Working Group on Nature Conservation

and Biological Oiversity - EC-Nature (revised version Sept. 1997)


. ANNEX V Item 4 HELCOM RECOMMENDATION 19/1 of26 March 1998 regarding MarineSediment Extraction in the Baltic Sea.

BALTtC MARINE ENVIRONMENT PROTECTIONCOMMISSION - HELSINKI COMMISSION -

Environment Committee (H~LCOM EC)Eighth Meeting

Vilnius, Lithuania20-24 October 1997

IDRAFT HELCOM RECOMMENDATION 19t}(#;

::lb[Adopted ~ March 1998,having regard to Articfe 13, Paragraph b)of the Helsinki Conventionl

MARINE SEDIMENT EXTRACTION IN THE BALTIC SEA AREA *)

THE COMMISSION,

EC 8/9715/1

Annex 10

•

RECALLING Paragraph b of Article 13 of the Convention on the Protection of the MarineEnvironment of the Baltic Sea Area, 1974 (Helsinki Convention),

NOTING Articles 3, 4, 7 and 15 of the 1992 Helsinki Convention,

TAKING INTO ACCOUNT that marine sediment extraction is of increasing economical'importance in many regions of the 8altic Sea Area,

BEING AWARE that marine sediment extraction may have severe impacts on marine andcoastal ecosystems,

TAKING INTO ACCOUNT that marine sediment extraction beside its' environmental andecological impacts also may interfere with other legitimate uses of the sea or interests suchas fisheries and coastal defence,

DESIRING to minimize environmental impacts caused by marine sediment extraction and toavoid irreversible ecosystem disturbances,

TAKING INTO CONSIDERATION the work done by ICES on this issue, inter alia the "Codeof Practice for the Commercial Extraction of Marine Sediments (including minerals andaggregates)",

RECOMMENDS to the Governments of the Contracting Parties to the Helsinki Convention:

a) to carry out all sediment extractions according to the attached Guidelines (Attachment1);

b) to carry out an "Environmental Impact Assessment" prior to the extraction permit;

c) that extraction permits for ,-Sensitive Areas" shall be granted only following therestrictions as defined by the attached Guidelines (Attachment 1);

d) that the "Extraction Practice- shall cause a minimum environmental impact and allowthe regeneration of marine and coastal ecosystems;

e) that "Environmental Monitoring" shall be carried out ?s a component of any sedimentextraction, " .

RECOMMENDS FURTHER that the Contracting Parties report to the Commission every threeyears, starting in 1999, using the attached reporting format (Attachment 2).

.• ) Study reservation by FinlandStudy reservation by Germany lextraction for the purpose of coastal protection)

lCES-WGEXT III April 1998

Attachment 1

Guidelines (ar Marine Sediment Extraction

Definitions

Marine sediment extraction means the removal of sand, gravel, stones and othersediments from the sea bed for purposes such as construction, beach nourishment,landfill or as industrial raw material.

Environmental Impact Assessment (EIA) means an assessment carried out on the basisof an act on environmental impact assessment or an assessment in connection withany extraction permit procedure that covers the points as specified in A. 1. a-i of thisGuidelines.

General

Decisions of national authorities on permits for marine sediment prospection and extractionshall be based on an adequate investigation and evaluation of the natural conditions, the

. ecological consequences and possible interferences with other legitimate uses of the sea.

A.. Environmental Impact Assessment

(1) An Environmental Impact Assessment shall be an obligatory part of the extractionpermission procedure. It shall take into considerationa) the amount and type of the sediment being extractedb) the composition of the aggregate (grain size structure, organic content,

contamination with harmful substances etc.)cl the extraction methodd) the species composition and abundance of benthic flora and fauna at the

extraction site and other areas potentially affected by the extraction processe) the significance of the extraction for fish, marine mammals and seabirds

(spawning, breeding, migration, feeding, resting)f) the possible alteration of chemical and physical parameters in the water column

and sediments (increase of turbidity, release of nutrients, harmful substances,oxygen consuming compounds)

gl the hydrological situation at the extraction site (waves, currents, salinity, watertemperature, sills and other structures with significance for hydrologicalprocesses etc.l, including its significance for the expansion of the turbidityplume, sedimentation of suspended material and water exchange

h) the duration of and the parameters for monitoring during the sediment extractionactivities and after its termination

i) interference with other legitimate uses such as fishery, coastal defence,recreation and tourism or possible damage to submarine archaeological sites.

(2) The Environmental Impact Assessment shall also consider effects on the sea bottomand the water column at the extraction site, as weil as outside the extraction areacaused , e.g. by turbidity plumes and sedimentation of particles. It shall also considerpossible effects caused by transportation of the extracted materials.

(3) The results of the Environmental Impact Assessment which has formed the basis forthe decision onthe extraction permit should be made available for scientific evaluation.


B. Sensitive Areas

(11 Permits for marine sediment extraction shall not be granted for:

al Nature reservesbl National Parks , I. ; " ",'

cl Areas to be included or which are proposed to the European ecological NATURA2000 network according to the EC Habitats and Birds Directives (92/43/EEC and79/409/EEC) except when the procedure of Art. 6 of the Habitats Directive isfollowed

(2) Permits for marine sediment extraction in other sensitive areas shall only be grantedif a thorough EIA that covers at least point A of this Guidelines is proving that theextraction is not Iikely to cause significant negative ecological effects or lead to adeterioration of the area. Such areas are:

al Baltic Sea Protected Areas (BSPA) according to HELCOM Recommendation 15/5bl Ramsar sitescl areas inhabited by communities of long-Iiving threatened invertebrate species

(e.g. the bivalves Arctica is/andica, Astarte sp., Macoma calcarealdl important spawning areas of fishel important feeding grounds for migrating or wintering waterfowl within resting

and wintering areas of international importancefl large areas densely covered with macrophytes (especially such as Fucus, Zostera,

Furcellarialgl submarine boulder fields on lag deposits [where they represent a rare or

particularly ecologically valuable habitat type) *hl areas of permanent upwelling cold water which provide habitat niches for

specialized threatened benthic speciesil submarine sills with significance for the water exchangejl marine areas near to the coast with significance for coastal sediment transport

or with protective function for the coastline (e.g. sand banks, spits and barsi.0:'·

C. Extraction Practice

• (1 I All appropriate measures shall be taken in order to minimize the ecological impactscaused by sediment extraction, and transportation of the extracted material. Thisincludes:al the choice of an appropriate extraction method which guarantees minimum

negative impacts to the marine environmentbl application of the "best available technology" (BAT) and "best environmental

practice" (BEP)cl optimization of the extraction process particularly in terms of reduction of the

turbidity plume

(21 Furthermore special seasonal susceptibilities of the affected area (e.g. bird and fishmigration, reproduction period of marine organisms) shall be considered.

(31 The recovery of marine Iife after termination of the extraction process shall befacilitated by appropriate precautionary measures. It shall be ensured that the originalsurface sediment type shall remain onthe bottom with an adequate thickness forrecolonization by almost the same benthic organisms assemblage that inhabited thesite prior to the extraction .

• ) study rescrvatiön by Denmark

leES - lrGEXT 1I3 April 1998

D. Environmental Monitoring

Monitoring shall be a component of every kind of extraction activities.

Dredging vessels should be equipped with monitoring systems for recording the position andthe amount of extracted sediments.

Spill monitoring shall be carried out, including the parametersa) amount and composition of spillb) dispersion of suspended particles of the turbidity plumec) sedimentation patternd) biological parameters (plankton, fish, sea birds etc.), as appropriate.

Depending on the extracted material monitoring mayaiso be necessary for oxygen andnutrients in the spill water, in the water column at the extraction site and in the turbidityplume; if the sediment contains harmful substances and release by the excavation processhas to be assumed the monitoring shall also include these parameters.

After termination of the extraction the recovery of benthic communities shall be monitoredas defined in the EIA.

Monitoring data should be made available for scientific evaluation.

•


........lJl

·Attachment 2

Reporting format for draft HELCOM Recommendation 19/xx concerning marine sediment extraction in the Baltic Sea Area

Please fill in the required information for all extraction fjelds of more than 10 ha extension or an annual extraction rate of more than 10.000 m3•

No. Location Year when the Type of Purpose of the Annual amount of extracted material EIA Environmental1) permit was material extraction during the reporting period (m3

) (yes/no) monitoring duringgranted 2) and/or after extraction

(yes/no)

19_ 19_ 19_

1) please, indicate on a map2) e.9. filling material, beach replenishment, coastal defence, industrial raw material, others

ANNEX V Item 5 1997 Review ofthe efTects ofextraction ofmarine sand and gravel on the Baltic ecosystem.•Uarine Em'ironmental Quality Committee lCES CM 1997:E4

7 REVIEW OF THE EFFECTS OF EXTRACTION OF MARINE SAND AND GRAVEL ON THEBALTIC ECOSYSTEM

The following section of the Annual Report of the ICES Working Group on the effects of extraction ofmarine sediments on the marine ecosystem reviews the information and discussions on the effects ofextraction of marine sand and gravel on the Baltic Ecosystem. This task, set out in the Terms ofReference for its meeting (C Res 199612:28 (a)), was requested by the Helsinki Commission (HELCOM1996/11) and required the provision of information on the extent and volumes of sand and gravelextraction in the Baltic Sea, and on known impacts on ego benthos, diving seabirds and bottom spawningfish and invertebrates.

In undertaking this task the Working Group was conscious that:-

i) certain historical activities in the Baltic Sea had not conformed with the ICES Code of Practiceand that observed deleterious impacts associated with these were a feature of this departure fromgood practice rather than illustrative of particular risks in the Baltic from extraction operations,

ii) that the sources of environmental disturbance associated with sand and gravel extraction in theBaltic Sea, providing good practice is followed, would be similar to those from extractionoperations found in other locations, but

iii) that the specific composition and structure of Baltic ecosystems are substantially different fromthose in the North Sea and NE Atlantic where extraction activities are undertaken by other states.

The consequence ofthis is that the Working Group in addressing potential effects have assumed that goodextraction practice would be followed and that the sOurces of environmental disturbance arising would besimilar to those noted elsewhere (see for example ICES Cooperative Research Report No 182). Theconsideration of potential environmental impacts has been limited by the need for more detailedinformation on the Baltic ecosystem, notably in areas ofvery low salinity, and the requirement for furtherevaluation involving specialists in these areas of Baltic Sea ecology.

The Working Group did not specifically address the potential physical effects of extraction operations oncoastal processes. Certain extraction operations in the Baltic have led to coastal erosion and alteredsediment transport patterns. These risks would usually be evaluated as part of the environmental impactassessment for any project (see ICES Guidelines for the preparation of an Environmental ImpactAssessment evaluating the effects of seabed aggregate extraction on the Marine Environment) and have •been discussed in detail elsewhere (lCES Cooperative Research Report No 182).

7.1 EXTRACTION OF MARINE SEDIMENTS IN THE BALTIC SEA BY COUNTRY

The following sections provide information on the reported aggregate extraction activities in Baltic states.It is known that aggregate extraction operations occur in other areas but data was not available to theWorking Group on these.

7.1.1 Denmark

The extraction ofmarine sand and gravel in the Danish Exclusive Economic Zone ofthe Baltic represents30-50 % of the total marine production of materials for construction and reclamation. Most of thematerial dredged comes from areas along the east coast of Sja:lland, 1'.10n and Falster and from AdlerGround-Ronne Bank and Kriegers Flak.

The amount of materials dredged for construction has increased slightly since 1992.

During the construction of the fixed link between Denmark and Sweden 3 xl06 m3 of sandfili will bedredged from the Kriegers Flak in the Baltic. The dredging started in January 1996 and is expected to last

4 years. To date, some 350,000 m3 has been dredged in this area.


Marine Environmental Quality Committee lCES CM 1997:E4

Table 7.1: Extraction of marine sediments from the Danish Exclusive Economic Zone of the BalticSea

..

Year Sand Gravel Gravel/Stones Sand fill0-2 mm 0-20 mm 6-300 mm

1990 0.2 xl06m) 0.1 xl06m) 0.2 xl06m) 0.1 xl06m)

1991 0.3 xl06m) 0.2 X 106m) 0.4 xl06m) 0.2 xl06m)

1992 0.3 X 106m3 0.1 xl06m3 0.7 X 106m3 0.2 x106m3

1993 0.3 xl06m' 0.1 xl06m' 0.6 x106

m'

1994 0.5 xl06m) 0.1 xl06m3 0.7 xl06m' 0.1 xlO6 m)

1995 0.6 xl06 m' 0.1 xIQ6 m' 0.5 xl06m'

• 1996 0.6 xl06 m' 0.1 xl06 m' 0.5 xl06m' 0.6 xl06 m'

* The figures for 1996 are preliminary.

7.1.2 Estonia

No data available to the Working Group

7.1.3 Finland

The volume of sand and gravel extraction varies from year to year and there are no official statisticsavailable. The annual average extraction of sand and gravel is, however, estimated to be less than 0.5x I06 tonnes. The principal areas where extraction operations have occurred in recent years are in coastalareas off the cities of Helsinki, Kotka, and Pori (in the Gulf of Bothnia).

7.1A Germany

• 7.1.5

In 1995, approx. 1 x 106 tonnes ofsand and gravel were dredged in the Baltic and in the coastal seas. It isexpected that especially dredging for coastal protection will have increased in 1996. The sand wasdredged from areas near the coast.

Latvia


7.1.6 Lithuania


7.1.7 Poland

6From 1985 to 1989, about lAx 10 tonnes of aggregates were dredged from the Slupsk Bank. In 1990,exploitation was stopped for economic reasons. Test dredging was carried out from the Southem MiddleBank and in Koszalin Bay during 1987-1989. Approximately 4,000-6,000 tonnes were removed fromeach deposit. During the 1990s, a few thousand tonnes of aggregates were extracted from the eastem partof Pomeranian Bay without any formal controls.

A 1 km! sand extraction field located 4 km north-east of Jastamia on the Hel Peninsula was used in 1993and 1995 for beach nourishment needs (total amount of extracted sand was ca. 200,000 mJ). Sand iscurrently extracted in a 5 km! area north-east of Cape Rozewie for the needs of artificial beachnourishment. It has been dredged since 1995 at a rate of 100,000 mJ/year.


Marine Environmental Qua/ity Commiuee lCES CU 1997:E4

Since 1989 sand has been extracted at four sites in the Puck Lagoon for sand nourishment on the HelPeninsula. Since 1993 two sites have been c1osed. From the remaining two areas sand is presentlyextracted at a rate of 150,000 - 300,000 m3/year, but this is planned to be (except in instances of coastalcatastrophy caused by storm activity) stopped by 1998. The total amount of sand extracted from the PuckLagoon is about 6,000,000 m3•

Sand is also extracted from approach channels to ports and from sand traps at ports within operation ofartificial sand by-pass systems; such extraction has taken p\ace since about 1990 at the ports of Kolobrzegca.60,000 m3/year), Darlowo (ca. 80,000 m3/year), Ustka (80,000 m3/year), Leba (30,000 m3/year),Wladyslawowo (ca. 200,000 m3/year).

7.1.8 Russia


7.1.9 Sweden

No commercial dredging has taken place in the Swedish Exclusive Economic Zone of the Baltic in recentyears.

7.2 OVERVIEW OF DATA ON THE ßALTIC SEA ENVIRONMENT

7.2.1 ßenthic communititcs in the Polish marine area

Distribution of the bottom macrofauna depends strictly on the type of the bottom in a given area. In theBaltic Sea sand is the dominating type of bottom sediment down to 50 m. In the deeper part of the sea thebottom is composed mainly of muddy sediment. Composition and spatial variability of benthic speciesalso reflect a whole range of diversity of environmental factors such as temperature, salinity, oxygencontent in both water and bottom sediments.

In terms of species composition and macrofauna abundance, six bottom macrofauna communities havebeen identified in the Polish Marine Area (Figure 7.1). The communities described below are namedaccording to the occurrence of the most characteristic species (the most frequently found, dominating interms of total biomass or abundance during the whole year). While the Working Group was only in aposition to consider such data for Poland it was of the view that this provided an important illustration oftypes ofbenthic community likely to occur in many areas ofthe Baltic. In the Northem and Eastem partsof the Baltic, however, benthic communities more characteristic of freshwater environments will occur; •no data was available to the Working group on these.

A - ,Uacoma baltlzica - Mya arenaria community occurring on sandy bottoms down to 20 to 25 m (thelimit of warm water during the summer). This is a very diverse community composed of 20 macrofaunaspecies, mainly of Atlantic or Atlantic-Boreal origin. Some fresh water species can be also found in thiszone.

In terms of abundance the most dominant species in this community is the sedentary polychaete Pygospioelegans. The bivalves Mya arenaria, Cerastoderma lamarcki, Macoma balthica and the amphipodCorophium volutator are common as weil. Bivalves make up about 90% of total biomass. Thesupralittoral zone (splash zone) is a hostile habitat for benthic species due to wave action. Only a fewspecies (Bathyporeia pilosa, Eurydice pulchra) are able to tolerate these conditions.

ß - Myti/us edulis - Gammarus salinus community occurs in the sandy-stony bottom ofthe Slupsk Bankat depths ranging from 141020 m.

Aigae cavered stones create a diversified habitat, enhancing the faunal diversity: same 18 species arerecorded including 11 crustacean species. In terms of both abundance and biomass Mytillis edlilis is thedominant species constituting 72 and 96 % of the total macrofauna, respectively. Among the otherspecies, only Gammarus salinus accounts for more than 1% of the total biomass.

1CES-WGEXT 118 April 1998

". t· ... ... ~ ." ~. ' .. ~.

Marine Em'ironmental Quality Committee ICES CJf 1997:E4

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:,:>::::L:{:i::iufIuiu:~:u':: :_---,,..-_::-:_~_·~_·~,..~_~_!_F,...;-_~_~~_:_;....;r:. . . . . . . .

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•Figure 7.1: Benthic macrofauna communities inhabiting Southern Baltic area

A - ,\[acoma baltlzica -,llya arenaria communityB - Mytilus edulis - Gammarus salinus communityC - ,lfacoma baltlzica - ,lfesidotea entomon communityD - Astarte borealis - Astarte elliptica communityE - Scoloplos armiger - Macoma baltlzica communityF - Lack ofbottom macrofauna

C - Macoma baltlzica - Saduria entomon community occurs in sandyasweIl as sandy-muddy bottoms at

a depth range of25 to 60 m.

Approximately 20 benthic macrofauna species can be found in this community. As far as biomass isconcemed Macoma balthica is the dominant species; however, the most abundant are the crustaceansPontoporeia affinis and Pontoporeia femorata. Macoma balthica and the crustaceans Saduria entomon,Pontoporeia affinis and Pontoporeia femorata are the most frequently occurring species in this

community.

D - Astarte borealis - Astarte elliptica community occurs in the clay, sand and gravel bottom of theslopes and sills ofthe Slupsk Furrow at depths between 60 and 90 m.

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The community consists of 20 specimens, with Astarte sp.• Saduria entomon. Seoloplos armiger andTerebellides stroemi predominating. The clams Astarte sp. found in this community only, predominatedboth in tenns of abundance and biomass, contributing about 66% and 87% respectively.

E - Seoloplos armiger - ,~faeoma baltMea community occurs in the least populated, mainly muddybottom area below 60 m.

This community comprises species which are able to tolerate extensive changes in oxygen concentrationsuch as the polychaetes species Seoloplos armiger, Bylgides sarsi, Areidea sueciea and also the mostubiquitous benthic species occurring in the Baltie Sea. Maeoma balthiea. In this eommunity the mostfrequent and abundant species, which also comprises a large part ofthe biomass, is Seoloplos armiger. Inthis zone it is possible to observe temporary disappearance of some species due to oxygen deficit as weilas recolonisation ofthe bottom after refreshed oxygen eonditions (inflow of oxygen-saturated water fromthe North Seal.

F - Lack of bottom macrofauna - the muddy bottom region, below 70 m is practically not inhabited bybenthic organisms due to the long tenn oxygen deficit. Only a few small organisms such as nematodesexist at this depth. Recolonisation in this area has been observed; however, it has usually been short tenn.

Significant dominance of bivalves is a characteristie feature of almost all communities exeept Scoloplosarmiger - Maeoma balthiea, where polychaetes contribute 50% oftotal biomass.

7.2.2 l\1acrophytes in thc Daltic Sea

The Baltic macrophyte community is composed of marine and limnic plants and algae. Most of themarine algae can also be found in the North Sea. Due to the specifie hydrodynamics and geomorphologyboth the limnie and marine species have to cope with physiologieal stress caused by the very large rangein salinity, annual temperature fluctuations and seasonal changes in the intensity of the light in northemareas. The substrate type is also of great importance, as the Southem Baltie and the Baltie Proper consistmainly of sand and finer sediment, macroalgae have few areas to attach themselves. These areas aredominated by perennial higher plants such as eel grass, pond weed and reed.

Since the 1960's growing evidence of a massive macrophyte decline has been reported. Climatie andhydrological changes, and euthrophication have been identified as the most important reasons for thisdecline. The increasing nutrient concentrations (P and N) stimulate particularly the primary production ofplanktonic algae and fast growing epiphytie green algae. As a result the community composition,production and depth contour of the Baltie flora has changed. The most objective changes are thedeclining perennial macrophytes, (eg Fueus and Zostera) and an increase of the algal blooms (Schramm1996).

From the 1950's to the end ofthe 1980's (Vogt & Schramm 1991; Schwenke 1965) a tremendous loss inabundance and biomass has been observed for Fueus in Kiel Bay due to a shift in the lower depth contourfrom 10 m to 2 m. During the same period the lower depth distribution of the red algae community inKiel Bay shifted from 20 m to 18 m, while the contour ofmaximum biomass moved from 14-16 m to 8 m.The community changed from a Fureel/aria sp. dominated to a Coeeotylus sp. and Phycodrys sp. one(Schramm 1996).

7.2.3 Fish in thc Daltic

There are around 200 species of fish [ound in the North Sea, but this number reduces in the brackishwaters of the Baltic with many of the marine species being replaced by purely freshwater species in theNorth and West ofthe ßaltic Sea (Table 5.2). No detailed information on freshwater fish populations wasavailable to the Working Group.

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Table 7.2: Change in fish species and relative abundance of marine and freshwater types

Marine Migratory Freshwater Total.. .. ~

species species speciesspeclesBaltic Total (without Kattegat) 97 7 40 144

Beltsee and Arkonasee (Western Baltie) 97 7 22 126Bornholmsee, Gotlandsee and Rigaer 41 7 23 71

Meersbusen (Baltic proper)Alandsee, Seharenmeer, Finnischer 27 5 33 65

Meerbusen and Bottensee(Northern and Eastem Baltie)

Bottenwiek 10 5 25 40

source: Thiel et al (1996)

In addition to eommereially important species, there are several speeies that are proteeted by the BemConvention, or which appear on the 3 protected fauna lists of the EU Habitats Direetive. The marinespecies in this eategory are shown in Table 7.3, but it should be noted that there will be several otherfreshwater species on these lists. Several of these species also spawn on seabed substrates or have doseassociations with the seabed environment.

While less produetive than the North Sea the Baltie Sea supports a produetive fishery, with the marinespecies of herring, sprat and eod the most eeonomieally important. Catehes of these speeies peaked in thelate 1970's and early 1980's but in reeent years eatehes have deelined. Reeruitment in the eod fisherymay have been redueed by the prolonged period of lowered salinity. While less important in eommercialterms there are also several fisheries for freshwater species.

Table 7.3 Marine fish species protected by the ßern Convention or appearing in the speciesprotected Iists of the EU Habitats Directive

Speeies Endemiclnon- Geographical distributionendemie

Alosa alosa non-endemie southern BaltieAcipenser sturio non-endemie allAlosafallax non-endemie allCoregonus aIbuIa endemie Gulf of Finland. northem Gulf of BothniaCoregonus Iavaretus 'J non-endemie allCottus gobio non-endemie allCottus poecilopus non-endemie southern and north-westem BaltieLampetra jluviatilis non-endemie allTriglopsis quadricornis non-endemie all(MyoxocephaIus)Petromyzon marinus non-endemie southern BaltiePomatoschistus microps non-endemie middle and southem BaltiePomatoschistus minutus non-endemie middle and southem BaltieSaImosaIar non-endemie all

<tl SubspeciesC. lavaretus lavaretus: gillrakers 22-29 (mean 25), usually smooth; Gulf of Finland and Gulf of ßothnia.C. lavaretus mediospinatus Pravdin: gillrakers 27-40 (mean about 35), mostly with denticulations; Gulf of Finland.C. lavaretus pal/asi Valenciennes: gillrakers 39-48 (mostly 42-44), usually with minute denticulations; Gulf ofFinland.C. lamretus oxyrinchus Linnaeus: gillrakers 35-44 (usually 40), snout pointed; western ßaltic and south-easternNorth Sea.C. lavaretus pidsclzianoides Pravdin: gillrakers 21-33 (usually 25-26), lower jaw abou! equal to caudal peduncledepth; south-eastern ßarents and White Seas.

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7.2'" Importance of the Baltic to seabirds

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The seabird fauna of the Baltic is primarily characterised by the almost 10 million birds estimated toovenvinter in the region (Durinck et aI. 1994). The winter bird fauna ofthe Baltic is numerieally dominatedby benthivorous species, especially seaducks whieh comprise about 80% of the total number of birds. Eightspecies occur in the Baltic in numbers representing more than half the number in Western Europe (Rose &Scott 1995) and hence these species are most likely to become detrimentally affected at the population level:Red-IBlack-throated Diver (Gavia stellatalarctica), Mute Swan (Cygnus olor), Long-tailed Duck(Clangula hyemalis), B1ack Scoter (Melanitta nigra), Velvet Scoter (Melanitta jusca), Smew (Mergusalbellus), Razorbill (Alca torda) and B1ack Guillemot, Baltic form (Cepphus g. grylle).

7.2.5 Sensitiye and Designated Areas and Habitats

lt was noted that the 62 Baltic Sea Protected Areas (BSPAs) provided a net\vork of protected sites ofconservation importance, that red book data were being worked on and that there is ongoing work onhabitats and threatened habitats. Further information on these is likely to be available in the comingmonths.

7.3 ENVIRONMENTAL IMPACTS AND IMPACT ASSESSMENT

The Worklng Group noted that several of the dredging operations in the Baltic on which it hadinformation had not conformed to good dredging practice. Departures from agreed good practiee (such asdredging fine material or dredging deep pits) may result in deleterious environmental effects, such as therelease of nutrients into the water column or the development of anoxie conditions. The Working Groupstressed the importance of dredging operations following the ICES Code of Practice and generally seekingto follow good dredging practiee.The Working Group commended to HELCOM the ICES Code of Practice and Guidelines onenvironmental assessment for the extraction of sand and graveI. lt noted the requirements under the EspoConvention (not yet in force) for impact assessments where projects may give rise to transboundaryeffects, and additionally the requirements of thc European Union with regard to EIA. It is assumed thatsuch projects would be subjeet to environmental impact assessments in the Baltic Sea area, whieh is theease in most North Sea and NE Atlantie areas.

The notes below have also highlighted the importance of a full assessment of risk to seabirds, fish, thebenthos and to other special habitats, in particular the Baltic Sea Protected Areas (BSPAs).

7.3.1 Chemical Impacts on scabcd and water column

Seabed disturbanee of sediments may result in mlxmg of the sediment with the overlying water.Additional inputs arise as a result of discharge of fine sediments from the dredger overflow whieh maygive rise to localised turbidity.

The disturbance of sediment with a significant content of fine material will result in the mixing ofinterstitial water with overlying seawater and potentially the release of chemieal eomponents from thesediments. The eomposition of the interstitial water is Iikely to be most strongly affeeted by organiematter within the sediments. For example, the deeomposition of this material ean lead to inter alianutrient and metal release from particulate to dissolved phases.

Decomposition of organic matter, desorption of components from organie matter and elay minerals, anddissolution of soluble material mayaIso oecur when sediment particles and water are mixed bydisturbance, during uplift or discharge. The effects ofmixing on the water column may include increasedeonsumption of oxygen by deeomposing organie matter and release of nutrients and metals. EquaIly,suspended elay minerals, with a high surface aetivity may aet as adsorbents ofsome dissolved species (eg.trace metals).

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Marine Environmental Quality Committee ICES CM 1997:E4

It should be emphasised that the chemical effects arising from aggregate dredging are likely to be minoron account of the very low organic and clay mineral content of the sediments suitable for commercialextraction. In addition, dredging operations are very localised and transient which further limits sucheffects.

7.3.2 Impacts on Benthos

The Baltic environment is potentially much less stable than the North Sea and English ChanneI. Forexample, in addition to the effects of natural sediment disturbance, caused primarily by wave action, thereare large scale spatial ~nd temporal variations in salinity and temperature which can range over the entireBaltic Sea bet\veen 2 - 30 and 5 - 12°C, respectively. Such conditions favour the development of abenthic fauna more typical of an estuarine environment, and deposits of sand and gravel in the Baltic tendto be dominated by species such as Macoma balthica, Mya arenaria. Mytilus edulis, Cerastodermaglaucum and llydrobia ulva. Research into the effects of sand and gravel extraction in the Baltic indicatesthat, where these animals occur, they quickly return to their pre-dredged status. Three examples provideinformation on the impact and the recolonisation ofthe macrofauna after dredging.

• • In 1988 an area called Slupsk Bank, off Poland, at a depth of 17 metres and a salinity of 7 psu(Okolotowicz, 199 I), was extensively dredged. An examination of the macrobenthos followingdredging indicated that the total number of taxa returned to the pre-dredged value within oneyear.

• In 1985 offthe town ofKotka in Finland (Winterhalter; 1990), 100,000 cubic metres ofsand wasdredged; this led to a significant deepening of the site down to 17 m, resulting in the totalelimination of the macrofauna. After one year, the number of species had returned to thebaseline level, but the abundance and biomass remained at a low level, suggesting that thecommunity would need several years to fully recover.

•

• Bet\veen July 1987 and March 1988, three million cubic meters of sand were dredged offDenmark in Koge Bay, creating 10 m deep pits with anoxie conditions having significant effectson the benthos below 7m depth (Norden Andersen et al. 1992). In addition, trailing suctiondredging removed up to 2 m on the sea floor, leaving a pattern of 1.5 m wide and 0.5 m deepfurrows on the sea bed. In this area the benthic macrofauna had recovered in numbers of taxa,abundance and biomass within 17 months after dredging. The settlement of musseis, however,on boulders (exposed by the dredging operation) changed the composition of the formercommunity.

However, there are a number of benthic species and communities which are of particular sensitivity. Forexample:

• Habitats whieh support large slow growing invertebrates, namely; Artica islandica. Astarte spp.• Areas with maerophytes whieh provide important habitats for many other invertebrates, such as

species of gastropoda (Rissoidae), isopoda (Cyathura) and amphipoda (Gammarus sp.).• Spawning areas for fish.• Areas of sea-bed whieh are important as feeding grounds for wintering sea dueks, such as eider,

seooter and long-tailed dueks.

7.3.3 Effccts on macrophytes in the Baltic Sca

Parts of the maerophyte distribution in the ßaltic Sea overlap with candidate areas for sand and gravelextraetion. As there are only a few studies which address growth and recolonization of maerophytes, thedredging of sand and gravel in areas stressed by euthrophication is of particular concern. As aeonsequenee, shallow eoastal sandy areas to 8m depth and boulder areas to 20m depth should be treatedas partieularly sensitive.


Marine Em'ironmental Quality Committee

7.3.4 [ffeets on fish and fisheries

ICES CM I 997:E4

In its Co-operative Research Report No 182, the Working Group stressed the importance of carefulevaluation of seabed spawning habitats where the Iicensing of gravel extraction operations is beingconsidered. The Report stressed, in particular, the requirement for herring spawning grounds andwhitefish (Coregonus) spawning grounds to be assessed where extraction operations were planned in theßaltic Sea area.

There are a number ofways in which aggregate extraction operations may affect populations of fish:-

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Localized avoidance of any disturbance caused by extraction activities (notably of suspendedmaterial in the plume ego Westerberg et al, 1996).Localized alteration of the benthos and possible reduction in food resources for certain fishspecies.Localized alteration of seabed habitat caused by removal of sediment and settling of suspendedmaterial (identified as of particular importance for bottom spawning fish with discrete spawninggrounds occurring in candidate extraction areas).Localized effects of suspended sediments on egg and larval stages (important also for pelagicspawning fish ego Westerberg el al, 1996). •

As with marine mammals turbidity in the water column may result in avoidance behaviour by fish species.The environmental assessment should evaluate potential impacts particularly for any species with criticalmigrations through any areas likely to be affected in this way. Given the size of extraction areas anyeffects of altered benthic communities on fish stocks is likely to be small and not detectable againstnatural variation in the fish stock. It is, however, important that all licensed extraction operations retainthe nature and type of the original surface sediment"1ayer and that no areas are dredged to a depth whichresults in an altered sediment type. Particular attention should be given to seabed spawning species andthis aspect ofthe biology of freshwater species requires further attention.

Recent work in the ßaltic has also highlighted the possible effects that suspended sediments mayaisohave on the buoyancy of fish eggs and on the survival rate of ichythyoplanktonic stages (Westerberg et al,1996). The adhering of particles to cod eggs causes loss of buoyancy and the eggs sink to the bottom.Given the avoidance reaction of fish to suspended sediments, it is difficult to extrapolate from this workthe likely effects on a stock but again critical spawning areas for pelagic spawning fish should also bereviewed in any environmental assessment.

Conclusions on Fish

The Working Group was ofthe view that the sources of environmental disturbance arising from extractionoperations that might potentially have effects on fish and fisheries would be similar in the ßaltic Sea tothose recorded for other areas. The fish species, their ecology and populations are, however, much morespecific to this sea area and this feature would benefit from further investigation involving those withspecialist knowledge of this aspect of Baltic Sea ecology. The principal means of ensuring extractionoperations do not have deleterious effects on fish and fisheries is good management. In this regard anyimpingement on either critical spawning seasons or critical migrations can be avoided by selectivelyhalting extraction operations at certain times of the year if necessary. Similarly, as elsewhere, Iicensedextraction operations may not be permitted on known critical seabed spawning habitats (eg. herringspawning grounds). The general view ofthe Working Group was that while the ßaltic Sea ecosystem wasunique and different from the truly marine areas where extraction operations occur, extraction activitiescould be properly managed so as to ensure no detrimental effects to fish or fisheries.

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7.3.5 Impacts on seabirds in the ßaltic

General

ICES CM 1997:E4

•

Only in a very few recent assessments has the extent and nature of the impact of extraction activities onseabirds been investigated. The populations and distributions of seabirds in the Baltic may be affected inthe following ways:

• Reduction of feeding conditions for plunge and pursuit diving birds through reduction of waterc1arity;

• Reduction of food resources for herbivorous species through negative impacts from sedimentdispersalon vegetation;

• Reduction of food resources for piscivorous species through negative impacts from sedimentdispersalon vegetation and fish larvae;

• Reduction of food resources for benthivorous species through removal of benthic communitiesand negative impacts from sediment dispersalon the settling of mussels;

• Avoidance of any disturbance caused by extraction activities.

The Working Group regarded all such potential effects as being localised and confined to the vicinity ofany extraction operation.

Potential impact on benthivorous seabirds

Assessments ofthe impact of dredging activities associated with the construction ofthe fixed links across theGreat Belt and the Sound support the general concept that impacts on seabirds are local and site specific(Tasker et al in press). No impact has so far been experienced in relation to the earth works in the Sound(Miljo- og Energiministeriet 1996), whereas a strong local «5 km radius from the source) effect on thenumber of wintering Eiders Somateria mollissima has been reported in the Great Belt (lensen & Skov 1997).The overall distribution of birds wintering in the Baltic is characterized by a large number of spatiallydiscrete areas with distinct populations with strong gradients in densities of birds occurring over shortdistances. This characteristic, the variation in the response of prey species on sediment loads and type ofextraction makes extrapolation of results from site to site very difficult.

Sensitive areas and habitats

Due to the heterogeneity ofthe distribution of seaducks in the Baltic, future research should be directed to thecore feeding areas in the coastal lagoons and on the offshore banks, where densities above 1000 birds/km2

may be found. All available information on seabird distribution and numbers in the Baltic has been puttogether in a geographical information system and published in Durinck et al (1994). Based on thisinformation, 39 areas of international importance for seabirds were determined, of which only 10 areasheld about 90% of the total estimated number of seabirds wintering in the Baltic Sea. Clearly, in thesekey areas, it is important that birds need to be given due consideration during the preparation ofenvironmental impact assessments in relation to future extraction activities.

Conclusions on birds

There are likely to be only limited and very local effects on bird populations from aggregate extractionactivities. Major concentrations of seabirds can readily be avoided by selectively choosing certainlocations and seasons.

Information necessary for an assessment:

• proportion of the total population represented by any specific area (here 1% threshold noted asrepresenting a frequently used threshold of significance)

• is the population ofregional or national importance?• is it a rare or protected species and/or is it endemie to the Baltic?• depth range for feeding (overwintering migrants and those staking)


JJarine Em'ironmental Quality Commiltee

• breeding sites etc for resident species.

7.3.6 l\1ammals

ICES CM 1997:E4

It was noted that effects on marine mammals had not been considered for the fixed link project.Populations of marine mammals seemed to be increasing. Haul-out sites were coastal and not likely to beaffected. There was a view that any indirect effects (loss of food chain production) would beinsignificant. Perhaps localised avoidance behaviour might be observed as the only direct effect.

Conclusion on mammals

Marine mammals should be considered in any environmental assessment but the view was that sucheffects were not Iikely to be of significant concern.

7.3.7 Conservation and Protected Areas

As a general role, dredging operations would not be permitted in conservation areas. The Working Groupfeit that any effects of dredging extraction were Iikely to be localised. However, specific local conditions •should be appraised and potential effects on any nearby protected or sensitive areas addressed in theenvironmental impact assessment. The Group noted that during dredging in Oresund a plume ofsuspended materials of up to 40 km has been observed. Such factors clearly require proper evaluationprior to the licensing of an extraction operation, but in many areas of the Baltic such turbidity would befar more localised perhaps only extending to 1000 m or so.

Conclusion on Protected Areas

Clearly, any licensed extraction activities should ensure the integrity of protected and sensitive sites and,for species, their favourable conservation status.

7.4 RECOI\1I\1ENDATIONS

7.5

The ICES Working Group on the Effects of Extraction of Marine Sediments on the Marine Ecosystem(WGEXT) should collect further information on the effects ofextraction ofmarine sand and gravel on theBaltic Ecosystem with the understanding that in 1999 a combined meeting of members of this WorkingGroup shall take place with members from HELCOM EC NATURE in one ofthe Baltic states.

REFERENCES FOR SECTION 7

Durinck, 1., H. Skov, F.P. Jensen & S. Pihl, 1994. Important Marine Areas for Wintering Birds in theBaltic Sea. EU DG XI research contract no. 2242/90-09-01. Ornis Consult report, 110 pp.

Jensen, F.P.J. & Skov, H. 1997. The number and distribution of Eiders Somateria mollissima wintering in theGreat Belt 1987-1996. With an assessment of the impact of sediment dispersal caused by theconstruction ofthe Great Belt Link. AIS Storeba:lt. 50 pp.

Miljo- og Energiministeriet 1996. 2. halvarsrapport om miljoet og oresundsforbindelsens kyst-til-kyst anla:g.Miljo- og Energiministeriet, Trafikministeriet, Kontroll- och Styrgruppen för Öresundsförbindelsen.42 pp.

Norden Andersen, O. G., P. E. Nielsen & J. Leth 1992. Effects on sea bed, benthic fauna and hydrographyofsand dredging in Koge Bay, Denmark. Proc. ofthe 12th Baltic Mar. Biol. Symp. I pp.

Okolotowicz, G. (1991): Benthos ofthe Slupsk Bank and the GulfofGdansk (Preliminary information).Data Ichthyologica et Piscatoria 21 (supplement): 171-179.

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Rose, P.M. & D.A. Scott, 1994. Waterfowl population estimates. IWRB Rapport No. 29, 102 pp.

Tasker, M., L. Canova. & G. Tucker (in press). A marine habitat conservation strategy for birds in Europe.BirdLife International.

Warzocha,1. (1997). Personal communication to the ICES WGEXT, April 1997. (Sea Fisheries Institute,Gdinya).

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Schwenke, H. (1965): Beitraege zur angewandten marinen Vegetationskunde der westlichen Ostsee(Kieler Bucht). Kiefer Meeresforsch. 21, 144-152.

Winterhalter, B. G. L. (1990). The Baltic marine environment as a source of aggregates and as a recipientof dredged material. In; D. A. Ardus and M. A. Champ (eds), Ocean Resources, Vol I:153+158. Kluiver, Netherlands.

Schramm, W. (1996): Veraenderungen von Makroalgen- und Seegrasbestaenden. In: Lozan et al. (eds.)Warnsignale aus der Ostsee. Parey Berlin.

Westerberg, H., P. Rönnback and H. Frimansson, (1996). Effects of suspended sediments on cod egg andlarvae and other behaviour of adult herring and cod. ICES C. M. 1996 (E:26 (MarineEnvironmental Quality Committee», 13 pp.

Vogt, H. & Schramm, W. (1991): Conspicuous decline ofFucus in Kiel Bay (western Baltic): what are thecauses? Mar. Ecol. Prog. Sero 69, 189-194.

Thiel R., Winkler H. and Urho L., 1996. Fische und Fischerei. pp 181 - 20 I in Warnsignale aus der Ostsee.Bfackwell Wissenschafts-Verlag, Berlin.

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