Restoration of the Bay of Torslandaviken

as a Natura 2000-area

Even wintering diving ducks like the Smew Mergus albellus need a dry, open, flat and safe shore to get some rest (Photo: Lars Carlsson)

Olof Pehrsson Ekologi-Konsult 2003

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Olof Pehrsson Ekologi-Konsult Tjuvkil 700, S-442 75 Lycke, SWEDEN Tel / fax +46 303 22 55 62 Mobil +46 706 71 38 50 e-mail: olof.pehrsson@swipnet.se

Restoration of the Bay of Torslandaviken as a Natura 2000-area

1. Introduction Early in 2000 the Bay of Torslandaviken, a remaining part of the River Göta Älv estuary in south-western Sweden, was qualified as an Important Bird Area (IBA) at the pan-European scale, supporting highly significant numbers of several waterbird species [1]. The area was adopted as an IBA-area (code 044) with special regard to whooper swan Cygnus cygnus, scaup Aythya marila and goldeneye Bucephala clangula [2] after preparatory work by en-gaged local ornithological societies. Later, according to a press release on July 6th 2000, Swedish authorities have designed the wetland Torslandaviken (SE0520055) as a Special Pro-tection Area (SPA) under Art. 4 of the Bird Directive 79/409/EEC. Species pointed out in this designation are whooper swan, smew Mergus albellus and ruff Philomachus pugnax. A total of 203 bird species have been recorded in the Bay [2]. Among them, 152 species are ac-counted for in Appendix 1, of which further 26 species are Natura 2000-species [3], the three selected SPA-species represent at least three important food and habitat types in the area (Ap-pendix 1).

The original boundary of the IBA-area, as proposed by the ornithological societies, has been considerably reduced by the Swedish Government (Appendix 2). This has resulted in an appeal to EU from local ornithological societies. So far, this has not resulted in any judgement by EU. But, in the meantime, the local authority, the Göteborg Community, as an owner of the Göteborg Harbour and origin of the unacceptable delineation, is trying to persuade the ornithological societies that habitats attractive to birds can be established together with an extension of the harbour in the Bay [6]. This comprehension is founded on the remarkable idea that a water surface forms the primary ecological key habitat in a Natura 2000-area sup-plying necessary food and cover to birds. This unscientific definition, considered by harbour and community officials to account for a considerable reduction of the original boundary, has been accepted and signed by Sveriges Ornitologiska Förening [7] without agreement from and information to the local and regional ornithological societies and before the report [6] was written. Since this conception unmasks the total absence of ecological knowledge behind the decision, this article is considered to repair this deficiency.

2. The estuarine function Estuarine environments belong to the most productive ecosystems on Earth [8]. The nutrients phosphorus and nitrogen are brought by the river water towards the sea. Sedimentation of clay particles in the slowing currents outside the widening river mouth formed shallow bottoms above which light starts high primary production. This is transformed to fish and bird food in food chains. Since currents are turning to the right on the Northern Hemisphere, this has fa-voured both fish and bird life in the Torslandaviken area. Before the arrival of wastewater treatment plants, the estuarine environment was dominated by detritus feeding organisms like the common mussel Mytilus edulis. After that, abundant dissolved and biologically available nutrients were utilized by phytoplankton and green algae. The estuary was overtaken by the

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cultural eutrophication. Now, as a result of effective phosphorus reduction in the wastewater treatment plants, primary production is reduced in the inner parts of the estuary, the Älvsborg Fjord. But, as the river water is gradually mixing with the phosphorus-rich bottom water, the eutrophication is maintained in the archipelago outside [9, 10]. The Bay of Torslandaviken on a level with the Rivö Fjord, halfway out in the estuary, is moderately affected by eu-trophication but has a high production of rooted and floating macrophytes constituting food to plant-eating birds and environment to aquatic invertebrates.

The opposite interest in the estuary has primarily been harbour activity. During the plan-ning in the 1960-ies, it was considered necessary to expand westwards along the coast. There was a want for ground surfaces for different terminal buildings and a starting off-shore activi-ties. The demand for special localities for discharge of dredged material was considered large as a consequence of planned large dredging projects in the harbour areas at the same time as the bottom sediments had high concentrations of high toxic pollution. Dumping in the sea was

Fig. 1. The Bay of Torslandaviken in the 1960-ies before the filling started.

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considered to be in doubt in view of environmental effects. Dredged material from the har-bour could contribute to the filling of the Bay of Torslandaviken. In this way, the sea was saved, since shallow estuarine bottoms were hardly considered as marine environments in a proper sense. The Bay was planned to be filled up to 2,5 m above sea level in 1977, but the expected demand for harbour and industrial installations failed to arrive. [11]

Filled water areas around the earlier island Hästholmen (Fig. 1) were given to Volvo and Danafjord AB. In the absence of industrial and harbour requirements, even areas within the suggested original Natura 2000-boundary are reserved for quite other interests. The lined wet-land area west of the island Karholmen (Appendix 2, Fig. 1) has rapidly been filled up for golfing. The green preservation area on the shore meadows north of the island Karholmen (Appendix 3) has been set apart for model flying-machines (toy aircraft), a noisy ac-tivity that may disturb both breeding and resting birds. The major road through the Torslanda community (Gösta Fraenkels väg) was placed close to the shore meadow (Appendix 3) on the earlier landing run-way (Fig. 1) of the former Torslanda air-port. Now, a road reserve for future local public transport is proposed on the shore meadows in the Natura 2000-area [6] as a justification for the reduction of the IBA-area. This means that people have to cross the major road with heavy traffic when walking from a bus stop to the community. A local road on the other side of the major road is said to be difficult because this area is marked for industrial purpose. Roads and a railway are proposed on both sides of the land area between the five basins A-E (Fig. 2). And this area in the middle of the Natura 2000-area is intended for future activities, obviously of industrial character. Though the originally suggested Natura 2000-area was situated outside the border of national interest for harbour activity, this border has now been moved out to comprise the whole Natura 2000-area.

3. Resting, moulting, wintering and breeding birds In the 1970-ies the Bay of Torslandaviken was found to bee the 4th most important shallow sea bay among 50 similar sites on the Swedish west coast with regard to fish-eating birds [12]. Large quantities of eel Anguilla anguilla has earlier been caught in the bay during spring and autumn [13]. The area was given the highest rank (1) in a classification of bird habitats of resting waders, ducks and passerines, hunting raptorial birds and moulting mute swans Cyg-nus olor and goldeneyes [14].

In the 1990-ies the bay was transformed to a lower class (2) in relation to its biological value [15]. This has to be seen as a concession and obligingness to demands for a develop-ment of the commercial and industrial life [11], because the biological development in the bay has been the opposite. Bird inventories along the Swedish West Coast performed during the

Fig. 2.. The 5 basins within the present Bay of Torslandaviken: A = Arendalsviken, B = Mellan-

bassängen, C = Södskärsbassängen, D = Stora bassängen, E = Södra bassängen.

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period 1968-1974 and repeated 1988-1989 show that the area has been developed towards a rich bird area with a higher status then it had before [16]. In spite of surrounding embank-ment, dumping of toxic dredged material and other waste material that considerably has re-duced the aquatic environment (cf. Fig. 1, Appendix 3), ducks geese and swans have arrived to the bay in increasing numbers (Appendix 1, Table 1). The explanation of this is that many of these birds have arrived to get food, because food is lacking in earlier feeding habitats that have been destroyed along the coast as a result of eutrophication.

The most remarkable change has occurred in tufted ducks Aythya fuligula and goldeneyes [4]. The wintering tufted Duck has declined from a maximum of 1650 to 200, depending on the reduced supply of detritus that earlier nourished a high production of their principal food in the estuary, the common mussel. On the contrary, the maximum number of goldeneyes has increased from 264 to 2100. This is a result of the eutrophication process that has suppressed most of the seed-producing eel-grass Zostera marina meadows along the Swedish west coast. Earlier, seeds from the plants and small molluscs (Hydrobia sp. and Rissoa sp.) on the leaves formed the principal food of resting and moulting goldeneyes but also of other ducks [12, 16-21]. Moreover, eel-grass leaves constituted food of wintering whoper swans that now have found a compensation area in Torslandaviken in numbers up to 200 birds. Also the two other IBA- and SPA-ducks, scaup and smew in numbers up to 30 and 75 respectively, utilising the same habitat, have increased. Among the 36 bird species (Table 1) getting their food in the aquatic environment exclusive of waders (fish-, aquatic invertebrate- and plant feeders) 7 (19,4 %) are Natura 2000.species and 15 species (41,7 %) are found on the Swedish Red List.

Among the 49 wader and shore birds, 11 species (22,4 %) are Natura 2000-species and 15 species (30,6 %) are on the Swedish Red List. The 3rd SPA-species in the area, the ruff, has been noted with a maximum of 400 birds. Almost half (46,2 %) of the birds of prey are Na-tura 2000 and Red List species. They are favoured by the abundant occurrence of prey, even among insect and seed feeding passerines constituting one third of all birds. Occurrence of rabbits Oryctolagus cuniculus and seed-feeding small rodents on the former islands increase the food supply to the avian predators.

4. Habitat types in relation to safety and food selection The three selected SPA-species represent the most important food and habitat types in the wetland area (Appendix 1, Table 1). However, wild birds also require certain protection from predators and also from human hunters. Even diving ducks and swans need a shore to get some rest (see cover). Then they search for open shores without tall vegetation, bushes and trees that may hide mammalian predators. Nor human activities and constructional work close to the water edge may render confidence in wild birds, whether resting or feeding on shallow water close to the shore. Many bird species adapted to an open landscape, like the ruff, require

Table 1. Occurrence of breeding (b) and resting (r) bird species in Torslandaviken (Appendix 1) in relation to food and habitat utilization

Natura 2000 IBA-species SPA-species Red List

b r b r b r b r b r

Fish feeders 1 11 4 3

Aquatic invertebrate feeders 5 15 2 2 1 1 10

Plant feeders 2 10 1 1 1 2

Terrestrial raptores 1 13 6 6

Wading and shore birds 14 49 1 11 1 2 15

Scavengers 2 3

Terrestrial invertebrate feeders 23 31 1 2 1 3

Fruit and seed feeders 6 20 2

Total

54 152 2 26 3 3 4 41

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a long distance to bushes and trees [22]. These require-ments import that the con-figuration of feeding, resting and also nesting habitats of water and shore birds also includes an open and undis-turbed land area of sufficient breadth (Fig. 3).

The submersed macro-phyte vegetation in the basins C and D (Fig. 2) is domi-nated by the fennel-leaved pondweed Potamogeton pect-inatus that is compensating for the disappearing eel-grass. This pondweed is found in nutrient-rich water [23] and has consequently an important function in the estuarine environment to incorporate the nutrients into food chains. The submerged meadows of this plant together with Ruppia- and other Potamogeton-species form the environment for invertebrates and fish that are used by all groups of aquatic birds. The vegetative plant material is grazed by the swans but also by increasing numbers of geese.

This aquatic habitat is also of importance to the group terrestrial invertebrate feeders, both breeding and resting birds, as a result of the high benthic production of midges (Chironomi-dae) in the basins. In addition to the breeding sand martin Riparia riparia (up to 100 nesting holes) even other swallows and swifts Apus apus visit the bay in large numbers (up to several thousands from May to Sep-tember) when the midges are swarming. The midges are also expected to favour breeding warblers like the whitethroat Sylvia communis (more than 5 pairs) that also may be a nesting host to eg-glaying cuckoos Cuculus canorus.

Earlier grazed shore meadows (Fig. 4) are over-grown and need urgent resto-ration. The breeding habitat of shore bird species like the redshank Tringa totanus and the blue-headed wagtail Motacilla flava flava is threatened. The embankment along the shore line of the basin D in north-west (Fig. 1 & 2, Appendix 2 & 3) has reclaimed the former grazed shore meadows that could be flooded up to the landing runway of the former air-port. Through a restoration of the original vegetation zonation in combination with cattle grazing in the whole area it should be possible to get back an optimal habitat to breeding dunlins Calidris alpina schinzii, of which breeding was noted as late as 1959.

Fig. 3. There are few open and natural shores, like this on the southern side of the island Flatholmen, left in the Bay of Torslan-

daviken. (Photo: O. Pehrsson 2003-09-02)

Fig. 4. The shore meadows in the northernmost part of the basin D (Fig. 2) are overgrown with bulrush Bolboschoenus maritimus and

common reed Phragmites australis in the water and increasoing bushes and trees. (Photo: O. Pehrsson 2003-09-02)

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A special bird habitat is obtained on the filling areas between the earlier islands Rörskäret,

Torsholmen, Flatholmen and St. Risholmen (Fig. 1 compared with Appendix 3). The filling material of different kinds of refuse matter that is resting on blast stone has given a dry ruder-ate habitat type [24] with high seed produc-tion. This habitat is especially utilized by wintering seed-feeding passerines. How-ever, this area, with shores along all the wa-ter bodies of the originally suggested IBA-area, is often passed by birds moving be-tween different feeding and resting sites in the basins. Because of this function, together with the necessity of safe feeding and rest-ing sites close to the shores, this terrestrial habitat, in absence of disturbing activities, can not retain this function if it is encum-bered with industrial establishments forcing ducks, geese and swans to cruise among industrial buildings and freight containers (Fig. 6).

One remaining habitat type may be saved in the surrounding landscape also with the function to maintain the open landscape. Until 1975, the black grouse Lyrurus tetrix was observed in the area. Earlier, this spe-cies was rather common in the archipelago and it belonged to the heather Calluna vul-garis heath. This scrub is already returning to the Vadskär area (Appendix 2) and it may be maintained on bedrocks on the earlier islands Karholmen, Torsholmen and Flatholmen through proper management.

5. Importance as a staging area in the re-gion The Bay of Torslan-daviken is shown to be of highest importance to migrating and wintering birds. This status is a result of its location in a bird migration route across the Swedish West Coast in northeast-southwest direction [17]. Many fresh-water wet-lands east-wards along this migration route are destroyed or badly man-aged. And, as shown,

Fig. 6. A borderline close to the water edge gives the possibility to dis-turbing and noisy activities that do not give any confidential impression to feeding and resting wild birds with an experience of man as a dangerous creature. This situation gives no possibilities to restore and to manage the

shore. The eastern shore of the basin B in Fig. 2. (Photo O. Pehrsson 2003-09-02)

Fig. 5. A borderline close to the water edge should allow filling with blast stone and refuse

matter with a steep slope that, as here on the east-ern shore of the basin D (Fig, 2), should deter even mute swans to graze on the floating vegetation near

the shore, where the vegetation is dampening the waves. (Photo O. Pehrsson 2003-09-02)

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marine resting sites along the coast have lost their earlier importance as a result of eutrophica-tion and also from exploitation. The international co-operation behind the creation of both CW (Convention on Wetlands)-listed and Natura 2000-areas has had the aim to save areas that are urgently needed to save both populations and threatened species. The increasing numbers of some species in the Bay of Torslandaviken, in spite of the unscrupulous exploita-tion of the environment, indicate the necessity of the international exertions. Some of the ear-lier resting sites that have lost their importance are found along the River Göta älv that is also situated along this migration route.

6. Restoration of the original border line A site boundary of a Natura 2000-area has to be drawn in relation to the habitat requirements of the birds. Consequently, the primary aim must be to restore the original borderline around the wetland area pointed out to be a Natura 2000-site. Borderlines drawn as in Appendix 3 that may allow exploitation of the kinds shown in Fig. 5 and 6 are not applicable in relation to habitats of wader birds as represented by the ruff. The variation of the water level as a result of tide, air pressure and strong winds is shown in Box 1. Consequently, a shore habitat comprises levels from 1,2 below and more than 1,5 m above the mean water level in the sea (Box 1). After a restoration of the shore meadows north west of the basin D (Fig. 2, Appendix 4), the whole area is flooded at high water levels in the sea. These variations also affect other shores around the basins and form the vegetation zonation that both the ruff and other wader and shore birds depend on. Wintering whooper swans also graze the flooded shore meadows that are managed through cattle grazing. The new demarcation proposal (Appendix 3 [6]) im-ports that the Natura 2000-are should be divided in three different parts. The resulting demar-cation line should exclude most of the landwards shore habitat and the adjacent protection zone against disturbance.

7. Earlier restoration proposals Two restoration projects are suggested earlier, both with the aim to favour shore birds in the sense of birds that have possibility to feed, rest and breed in the area. This habitat type is a

Box 1. Characteristic water levels in the sea [11]. + 1,50 HHW highest high water + 1,00 MHW mean high water ± 0,00 MW mean water - 0,70 MLW mean low water - 1,20 LLW lowest low water

Fig. 7. In absence of cattle grazing, the overgrowth is now far advanced on the shore meadow in north-west with bulrush Bolboschoenus maritimus and common reed Phragmites communis in depressions

close to the mean sea level (±0). (Photo: O. Pehrsson 2002-07-27)

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deficiency commodity in the Bay of Torslandaviken, because most of the original natural shores are destroyed.

The shore meadow in north-west (Fig. 7, Appendix 4, cf. Fig. 1 and Appendix 2) was em-banked when the Torslanda Air Port was built in the 1940-50ies and was used until 1977 [27]. Cattle then grazed the meadows between the former runway and the embankment along the shore, but not during later years. A restoration of these drained meadows may be performed through a removal of the embankment and through a resumption of cattle grazing [25]. Bushes and trees have to be removed with the exception of minor groups of trees in the north-ernmost part that may give shelter during warm summer days. The suggested new bank (

in Appendix 4) should not be higher (< +2,00) than the present embankment and should allow

grazing cattle to pass to un-flooded pastures on both sides at high water levels in the sea.. In order to receive an optimal pasture habitat for birds a sufficient grazing pressure has to be combined with man-agement measures that favour grass-species (Puccinellia, Agrostis) that are favoured by both cattle, geese and whooper swans.

The Southern basin (Fig. 8, Appendix 5, Fig. 2: E) is proposed to be formed as a shallow wetland for breeding and resting wader birds after the dredge filling is finished [26]. The toxic dredge has to be isolated with a surface layer (~ 0,4 m) of clay and other acceptable material, of which the surface is formed according to Appendix 3. Because this basin is elevated high above the sea level, estuarine water has to be pumped into the basin. Flat breeding islands (Appendix 5: 1-6) adapted to the requirements of the Natura 2000-species avocet Recurviros-

Fig. 8. The Southern basin (Fig. 2: E, Appendix 5) from south-east. (Photo: O. Pehrsson 2000-07-27)

Table 2. Areas and water volumes in the Southern basin according to the principal drawing in Ap-pendix 5 with possible flows at alternative pumping capacities. The maximum water level = ±0.

Area Volume Flow (L s-1) at tapping during Pumping in (h) with NETAB pump

(ha) (m3) 10 days 15 days 60 L s-1 * 125 L s-1 **

250 L s-1 ***

Islands

0,41

Depth: 0,00 - -0,10

3,94 13395 15,5 10,3 62,0 29,8 14,9 -0,10 - -0,20

3,79 9534 11,0 7,4 44,1 21,2 10,6 -0,20 - -0,30

3,62 5830 6,7 4,5 27,0 13,0 6,5 -0,30 - -0,40

4,02 2010 2,3 1,6 9,3 4,5 2,2 Total water surface

15,37 30769

142 68,4 34,2 The total area

15,78

Energy required: * I-0, 3 kW

** I-1, 5,5 kW

*** I-2, 11 kW

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tra avosetta, sandwich tern Sterna sandvicensis and common tern Sterna hirundo are sug-gested. A similar saline water basin in the Getterö-reserve [28-29] has been used as a model. A fluctuating water level, similar to the natural tidal variation should favour food organisms and they should be brought to this environment as eggs and larvae. In a preliminary water regime (Box 2.), water levels are adapted to both breed-ing and resting birds. Birds breeding on the is-lands require water around their nesting islands. A later lowering of the water during migration increases the concentration of food organisms and wader birds obtain a larger foraging area. An optimal water environment may be obtained through measurement of salinity, sampling of invertebrates and bird observations.

In order to maintain natural openness around this habitat type, bushes and trees on the sur-rounding banks must be removed.

8. Water regime in the basins Water levels in the basins A

D (Fig. 2) depend on the prevailing levels in the sea, at least at levels > ±0,00. Aren-dalsviken (A) is an excep-tion, since this basin is con-nected with the sea through a narrow sound. The basins B and C are connected with A through culverts (Fig. 9) which may prevent the low-est levels in the sea. The cul-vert between C and D is sup-plied with a threshold at ± 0,00 (Fig. 10). This imports that lowest water level in Stora bassängen (D) corre-sponds to the mean water level in the Sea. As a conse-quence of this, no water en-ters Stora bassängen from the Sea during dry periods with high air pressure and low water levels in the Sea. Dur-ing such periods, however, the water level in D may be reduced through evaporation and non-appearance of freshwater. This may be fol-lowed by increasing salinity. An other disadvantage is that less nutrients are brought to

Box 2. A preliminary water regime sug-gested in the Southern Basin [26]: 1/1-25/6 ±0,00 25/6-10/7 lowering from -0,00 to -0,10 10/7-25/7 lowering from -0,10 to -0,20 25/7-10/8 lowering from -0,20 to -0,30 10/8-25/8 stable level at -0,30 25/8-10/9 elevation from -0,30 to -0,20 10/9-25/9 elevation from -0,20 to -0,10 25/9-10/10 elevation from -0,10 to ±0,00 10/10-31/12 stable level at ±0,00

Fig. 9. The culverts from basin B to basin C. The water level in the Sea at the occasion ~ -0,06. (Photo O. Pehrsson 2003-09-02)

Fig. 10. The threshold inside the culvert from basin D to basin C. Water is still flowing out together with some sticklebacks Gasteros-teus aculeatus because the water level in the Sea was lower (~ -0,06)

(Photo O. Pehrsson 2003-09-02).

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Stora bassängen (D) in comparison with A

C.

The threshold between C and D (Fig. 2) was built in order to prevent a flow of toxic com-pounds to leave basin D when toxic dredge from the harbour together with water was pumped into Södra bassängen (E). The surplus of water was allowed to flow to D, but this flow also contained clay that has made the southern part of D more shallow than before (Fig. 1). This imports that the sediments in basin D, but also in the other basins, may contain toxic com-pounds. A water regime that contributes to cover older toxic sediments has to be brought about.

The tide-water in the area, about 10 cm (Table 3) together with effects from air-pressure and winds, imports that water enters from A to D but then re-turns the same way. When the water level in the Sea is < ±0,00 the wa-ter returns already in Södskärs-bassängen (C). In this latter situation only 22,78 ha (ba-sins A C) are supplied with nutrients, whereas Stora bassängen (90,51 ha) gets nothing. Only 20 % of the whole area is supplied with more phosphorous (P) and nitro-gen (N) that are necessary to produce vegetative and

Table 3. Area of the basins A D and water volumes and water currents required for a tide-wave corresponding to 0,1 m [11].

A

B

C

D

Total

Area (ha) 11,52

1,35

9,91

90,51

113,29

Volume (m3) from an elevation of 0,1 m 11520

1350

9910

90510

113290

Corresponding flow during 6 hours (L s-1) 533

63

459

4190

5245

Outlet D

Skepp-stad-holmen

E

Fig. 11. Proposed outlet from Stora bassängen (D) to Skeppstadviken through a cul-vert supplied with a unidirectional valve mechanism.

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animal food organisms to fish and birds. This explains way the shallow Södskärsbassängen (C) usually is visited by most birds in a comparison with Stora bassängen (D).

A unidirectional current through the basins has been proposed [11, 9]. The method is used on the Atlantic in USA to furnish fish and crayfish (personal observations) To attain this, the threshold between C and D has to be removed. A culvert (Fig. 11),

supplied with a unidirec-

tional valve mechanism, should be built from the southern border of basin D to the Bay of Skeppstadviken (cf. Appendix 3 and 5). A similar valve has to be built at the southern end of Arendalsviken (A, Fig. 2), between the former islands Hästholmen and Flatholmen (Fig. 1). At rising water level in the Sea, the A-valve is opened and the D-valve is shut. Nutrient-rich water enters the basins. At lowering tide, after six hours, the A-valve is shut and the D-valve is opened. Water with reduced nutrient concentrations is leaving the basins. The water regime obtained in this way is advantageous is several ways:

Nutrients (N and P) are reduced in an estuarine environment, almost the only remaining in the Göta Älv esturay.

Nutrients a transformed to biomass instead of being brought out into the archipelago caus-ing eutrophication.

The high production in food chains ends with fish and birds and nutrients are kept in bio-mass instead of being transported to the Sea as inorganic compounds.

Migrating birds may use the increased biomass of plants, invertebrates and fish to a higher extent.

In autumn birds can stay longer utilizing the abundant food and avoid competition in their winter quarters.

Birds wintering in northerly areas may avoid competition in more densely populated win-ter quarters.

During spring, early migrants like the whooper swan depend on favourable feeding sites in a migration corridor during periods with weather deterioration.

Birds, supplied with optimal resting sites during spring migration, may get a more success-ful reproduction if they reach the breeding site with a high body condition.

9. Restoration and management to maintain and improve habitat quality The land areas between the basins and the original IBA borderline also have important functions to-gether with the aquatic parts:

They form together the shape of nature landscape that has been typical to the Swedish West Coast. Sheep and cattle earlier grazed the rocky islands (Fig. 1). As a result, they usually lacked both bushes and trees. An open landscape was prevailing.

Most migrating wet-land birds are adapted to an open landscape both in

Fig. 12. After ceasing grazing the former grass and heather vegetation on the island Karholmen has gradually been transformed to bushes and trees.

(Photo: O. Pehrsson 2003-09-01)

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their breeding areas and in their winter quarters. A resting site like Torslandaviken is conse-quently more inviting and confidential if it is brought to an earlier state.

Many aquatic birds prefer to place their nest at some distance from the shore but not among bushes and trees.

On the former island Karholmen (Fig. 12) most bushes and trees have to be re-moved. Some group of trees is left to give shadow to grazing animals. This grazing pen (Fig. 14) is extended to com-prise the banks along the south-ern shore of Stora bassängen (D). Sheep should preferably graze this pen.

The former hilly islands Tor-sholmen and Flatholmen (Fig. 13) have similar vegetation as the island Karholmen. The adja-cent ruderat vegetation (Fig. 15) is unsuitable to grazing animals. However, this seed-producing vegetation is very valuable to seed-feeding birds and rodents. Thus, management should be restricted to a reduction of trees.

The Vadskär area (Fig. 16, red colour) is dry and covered with stone powder (Fig. 17). The vegetation is sparse, but the most suitable plant, heather, is slowly entering (Fig. 18). This point of land has to be kept free from bushes and trees close to a water area that is expected to

Fig. 14. The grazing pen Karholmen (green).

Fig. 13. Ruderat vegetation (green) around the former islands Torsholmen and Flatholmen

(brown).

Fig. 15. The dry earth layer filled above blasting stones only gives a habitat of seed-producing plants. Trees only grow on the

former shores of the islands. (Photo O. Pehrsson 2003-09-02)

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be highly frequented by birds. The shore meadows around the inlet north of Vadskär (Fig. 16, green) should be grazed by cattle in a pen that is a part of the adja-cent, large and restored shore meadow in Appendix 4.

When the stone crushing ac-tivity on Rörskäret-Vaskär (Fig. 1, 19) is ceasing, the remaining mound of crushed stone sand has to be left. It is an important breed-ing site for the sand martin Ri-paria riparia with about 270 nest-ing holes in 2000 [4]. The ground with stone powder as on Vadskär may develop towards a heather heath in the future.

Thus, management of the open landscape around the aquatic environments constitutes reduction of bushes and trees, grazing by sheep in one area and grazing by cattle in another area. The principal purpose of this work is to get as large safe dis-tance as possible to disturbing activities.

10. Swedish application of the EU legislation concerning Na-tura 2000 A Natura 2000-area as the Bay of Torslandaviken is expected to restored and managed not only as a habitat to three bird species selected among a total of 26 Natura 2000-species ob-served in the area (Table 1). But, as shown above, proper management of the habitats of the three species may also be favourable to most of the other species.

Fig. 17. The dry Vadskär heath where bushes and trees should be removed in favour of heather. (Photo O. Pehrsson 2003-09-02)

Fig. 16. The Vadskär heath (red) and the shore meadows around the

inlet (green)

Fig. 18. Heather Calluna vulgaris is already expanding on the stony and sandy substratum on Vadskär. This plant should be

favoured on all the hilly former islands around Torslandaviken (Fig. 13, 14, 16) in order to retain the open landscape and to

restore the former habitat of the blackcock Lyryrus tetrix . (Photo O. Pehrsson 2003-09-02)

Fig. 19. The stone crushing area on Rörskäret-Vaskär with the sand martin nesting site in the background. . (Photo O. Pehrsson

2003-09-02)

15

The Natura 2000-conception is an international but also a national interest. An earlier na-tional harbour interest was restricted to areas outside the original borderline. The newly ex-panded national harbour interest, comprising the original Natura 2000-area, is found to belong to quite other activities.

In this report consideration has been taken to ecological demands of the habitats (Artikel 6-2.3.3) and deterioration of habitats as a result of reduced borderline (Artikel 6-2,3,4), [30].

11. Social importance of a wetland In many Swedish cities, the authorities have been aware of the value of a wetland close to the town. Kristianstad has Kristianstad Vattenrike, Kalmar has Kalmar Dämme, Örebro has Kvis-maren, Karlstad has Karlstads Delta, Skara, Skövde and Falköping have Hornborgasjön and Varberg has Getterön. About 25 years ago, The Getterö reserve, which as an estuarine environ-ment has been a model in many regards to the Bay of Torslandaviken, suffered a similar con-flict between exploitation and preservation inter-ests as is now going on in Göteborg. Thanks to the international co-operation through CW-listing (the Ramsar Convention), the nature in-terest was victorious, a result that has given an important tourist attraction to the town. Now, the Natura 2000 legislation is expected to give a similar attraction to Göteborg for the future.

In well-managed wetlands the nature with its birds is a wonderful place for recreation and teaching [31]. The Bay of Torslandaviken is de-scribed as a valuable resource in the school work [32]. However, the history describing the trans-formation of a peaceful and productive estuary to a toxic, industrial environment is frightening [33-35]. The close distance between two opposite interests in the bay, exploitation or preser-vation of a small remainder of valuable nature illustrates the present economic advantage in relation to nature.

12. Transformation of a waste deposit area to alive wetlands A few decades ago, the Sea and especially shallow waters were considered capable to take charge of all kinds of waste material. In the Göta älv estuary the purpose was also to get in-dustrial and harbour space. The risk of dispersion of toxic compounds was not much taken into consideration. Very few analyses were made to control occurrence of toxic compounds in organisms. Now it is possible to repair some of this careless acting. It is still possible to man-age the remaining part of the estuarine Bay of Torslandaviken in a way that maintains an op-timal ecosystem with functioning habitats both to Natura 2000-species and other organisms in an environment that is not leaching toxic compounds in the future.

13. Summary The remaining rests of the Bay of Torslandaviken in the Göta älv estuary can not be reduced further if the present denoted habitats of Natura 2000- and other bird species have to be pre-

Fig. 20. So far, people are not welcome to the Natura 2000-area the Bay of Torslan-

daviken(Photo O. Pehrsson 2003-09-02)

16

served. Since the adduced national interest for harbour activities so far has resulted in quite other utilisation, the present planned activities as roads, railway and other industrial and lei-sure interests are hardly credible. The original IBA-border in a coherent Natura 2000-area must be recommended. Only then, can preservation according to the Bird- and Habitat Direc-tives be realised.

References [1] Bibby, C.J. 2000-01-07. To whom it may concern. BirdLife International. Letter. [2] Heath, M.F. & Evans, M.I. (eds). 2000. Important Bird Areas in Europe: Priority sites for conservation. Vol. 1. Cambridge, UK: BirdLife International (BirdLife Conservation Series No. 8). [3] Gärdenfors, U. (ed.) 2000. The 2000 Red List of Swedish Species. ArtDatabanken, Uppsala. [4] Thulin, J., Jacobsson, S., Andersson, R. & Ström, K. 2001. Torsvikens fåglar en artlista med sedda arter 1950-2000. Pp. 82-100, in: Torslandaviken industriell bakgård eller fågelparadis. Vår Fågelväld, supplement 34. Göteborg. [5] Ström, K. 2001. Torslandavikens status från en utfyllnadsepok i ett jungfruligt kustlandskap till ett eu-ropeiskt Natura 2000-område. Pp. 51-60, in: Torslandaviken industriell bakgård eller fågelparadis. Vår Fågel-väld, supplement 34. Göteborg. [6] Lagercrantz, J. 2003-07-01. Förslag till samverkanslösning Torsviken. Slutrappoert projekt samverkan Torsviken. Miljöbyrån Ecoplan AB. Göteborg. 10 pp. [7] Johansson, G., Nilsson, E. & Welander, B. 2003-06-12. Protokoll fört vid möte mellan Göteborgs Stad, Gö-teborgs Hamn AB och Sveriges Ornitologiska Förening kring Torsvikens utveckling. Minutes, 1 p. [8] Odum, E.P. 1971. Fundamentals of ecology. Sounders Company, Philadelphia. [9] Pehrssson, O. 2001. Torslandaviken som en fungerande rest av Göta älvs estuarium. Pp. 61-65, in: Torslan-daviken industriell bakgård eller fågelparadis. Vår Fågelvärld, supplement 34. Göteborg. [10] Pehrsson, O. Nutrient loading and reduction from source-lake to sea. Manuscript. [11] Pehrsson, O. 1996-09-20. Torsviken: ekologisk restaureringsmodell. Manuscript. 40 pp. [12] Pehrsson, O. 1979. Grunda kustområdens betydelse för förekomsten av sjöfågel och säl sammanställning och bearberning av ett inventeringsmaterial för norra Halland och Bohus. Natur och kulturvårdsprogram för Göteborg. [13] Enequist, P. 1972-03-24. Ans. Av Göteborgs kommun om tillstånd att utföra muddertippning och utfyllnad med muddermassor i Torsviken, Göteborgs kommun. (Statement from the Fishery Intendant to the Water Court) [14] Fastighetskontoret. 1979. Natur- och kulturvårdsprogram för Göteborg. Rapport 3, natur. [15] Stadsbyggnadskontoret. 1992. Ekologiskt särskilt känsliga områden i Göteborgs kommun. Översiktsplan för Göteborg. Underlagsmaterial (karta). 5:92. [16] Pehrsson, O. 1990. Vilka miljöförändringar indikerar sjöfåglarna utmed västkusten? (Summary: Which environmental changes are indicated by waterfowl on the Swedish west coast?) Fauna och flora 85(3-4):166-174. [17] Pehrsson, O. 1975. Regional, seasonal, and annual fluctuations of the goldeneye, Bucephala clangula (L.), on the Swedish west coast. Viltrevy. Swedish Wildlife 9:241-302. [18] Pehrsson, O. 1976a. Food and feeding grounds of the Goldeneye Bucephaka clangula (L.) on the Swedish west coast. Ornis Scand. 7:91-112. [19] Pehrsson, O. 1976b. Estuarine production of waterfowl food on the Swedish west coast. Pp. 221-226 in: Fresh Water on the Sea. Proceedings from a symposium on the influence of fresh-water outflow on biological processes in fjords and coastal waters, 22-25 April 1974, Geilo, Norway. [20] Pehrsson, O. 1984. Diving duck populations in relation to their food supplies. Pp. 101-116 in: Evans, P.R., Goss-Custard, J.O. & Hale, W.G. (eds.): Coastal waders and wildfowl in winter. Cambridge University Press, Cambridge. [21] Pehrsson, O. 2001. Hur västkustens rastande och ruggande knipor kom till Torslandaviken. Pp. 35-37, in: Torslandaviken industriell bakgård eller fågelparadis. Vår Fågelväld, supplement 34. Göteborg. [22] Svensson, S., Svensson, M. & Thernberg, M. 1999. Svensk Fågelatlas. Vår Fågelvärld, supplement 31. Stockholm. [23] Mossberg, B., Stenberg, L. & Ericsson, S. 1992. Den svenska floran. Wahlström & Widstrand. [24] Ljungstrand, E. 2001. Pp. 45-50, in: Torslandaviken industriell bakgård eller fågelparadis. Vår Fågelväld, supplement 34. Göteborg. [25] Pehrsson, O. 2002-09-17. Förslag till restaurering av strandängar i Torslandavikens Natur 2000-område. Manuscript. 6 pp. [26] Pehrsson, O. 2003-06-11. Förslag till utnyttjande och utformning av Södra bassängen i Torslandaviken som Natura 2000-område. Manuscript. 7 pp. [27] Wessberg, W. 2001. Gränsland i förändring. Pp. 12-17, in: Torslandaviken industriell bakgård eller fågel-paradis. Vår Fågelväld, supplement 34. Göteborg.

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[28] Pehrsson, O. 1993. Saltvattensbassängen i Getteröns naturreservat: tillkomst och avsedd funktion. Medde-lande från Getteröns fågelstation. 29:58-69. [29] Flodin, L.-Å. & Hirsimäki, H. 2002. Getteröns restaurering. Vår Fågelvärld 61:14-21. [30] Europeiska gemenskaperna. 2000. Skötsel och förvaltning av Natura 2000-områden. Artikel 6 i art- och habitatdirektivet 92/43/EEG. ISBN 92-828-9142-9. [31] Blomgren, R. 2001. En plats för rekreation och undervisning. Pp. 66-69, in: Torslandaviken industriell bak-gård eller fågelparadis. Vår Fågelväld, supplement 34. Göteborg. [32] Hägg, C. 2001. Torsviken som pedagigisk resurs i skolarbetet. Pp. 70-72, in: Torslandaviken industriell bakgård eller fågelparadis. Vår Fågelväld, supplement 34. Göteborg. [33] Larsson, K. 2001. Barndomsminnen från Syrhåla. Pp. 7-8, in: Torslandaviken industriell bakgård eller fågelparadis. Vår Fågelväld, supplement 34. Göteborg. [34] Eriksson, F. 2001. Syrhåla

axplock ur en bygds historia. Pp. 9-11, in: Torslandaviken industriell bakgård eller fågelparadis. Vår Fågelväld, supplement 34. Göteborg. [35] Wessberg, W. 2001. Grän-sland i förändring. Pp. 10-17, in: Torslandaviken industriell bakgård eller fågelparadis. Vår Fågelväld, supplement 34. Göteborg.

Lycke November 7th 2003.

Olof Pehrsson Dr. Phil.

The author of this report is a Senior Researcher associated with the Department of Zoology at the University of Göteborg. He has special-ised on the ecology of wetland birds and their habitats in both fresh and saline water. After disputation (Pehrsson, O. 1976. The importance of food in the regulation of some diving duck populations. Department of Zoology, University of Göteborg. Thesis.) Applied studies have been performed in a lot of wetlands resulting in management and restoration plans. Among these also some CW-listed wetlands are found: Lake Hornborgasjön, Lake Östen, Lake Kvismaren and the Getterö reserve. An international reward is obtained is obtained from The Foundation for Environmental Conservation as a recognition of published results (Pehrsson, O. 1990. The history of Lake Hornborga: A lesson in wet-land function and management from Sweden. Environmental Conser-vation 17(3): 245-255).

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