Dynamic and Ecological Role of Mussel Farms in a Mediterranean Coastal Area

Solidoro C., Beran, A., Cabrini M., Cummaudo F., Del Negro P.,De Vittor C., Fornasaro D., Guardiani B., Libralato S., Lipizer M., Minocci M., Monti M.

Istituto Nazionale di Oceangrafia e di Geofisica Sperimentale - OGSDept. Oceanography & Dept. BiologyTrieste, Italy

INTERREG III - ECOMADR Project

Endorsed by

Mussel farming in the Gulf of TriestePart of the ECOMADR project (1.5 y; Scientific Coordinator: Cosimo Solidoro) was dedicated to a preliminary study of dynamics and role of mussel farms in the Gulf of Trieste (North Adriatic Sea, Italy):

approx. 200’000 m of ropes, 4’000’000 m2 of surface; potential prod. 8’000 ton/year; value 1.6 million €/year

Adriatic Sea

MediterraneanSea

Issues and problems:1- impacts on water & sediments quality;2- trophic interaction with other marine resources (small pelagics?);3- yearly fluctuation of production;

Issues, aims and methods

Biogeochemical measurements in water & sediment inside the farm and in the reference station (DOC, POC, nutrients, Chl-a, Pheo, LOM, etc)

1- impacts

2- trophic interactions

Qualitative evaluation of mussel diet(gut content)+ Plankton populationsin farm’s water and reference station

3- performance production

Growth measurements (2 coorts x 1 year)+ bioenergetic model of mussel

ECOMADR Project

1- Impacts of mussel farms on water quality

Chl-a and Pheosystematicallylower in musselfarm than inreference site:effect ofmussels’ grazing

0

0.5

1

1.5

2

2.5

3

Sep-06 Oct-06 Nov-06 Dec-06 Jan-07 Feb-07

µg l-1

Chlorophyll

Pheopigments

Reference site (T21)

Mussel farm (M3)

M3(mussel farm)

T21(reference site)

Dissolved and Particulated OrganicCarbon are generally higher in the mariculture site

1- Impacts of mussel farms on water quality

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Sep-06 Oct-06 Nov-06 Dec-06 Jan-07 Feb-07

mg

l-1

DOCPOC Reference Mussel farm

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Sep-06 Oct-06 Nov-06 Dec-06 Jan-07 Feb-07

µM

N-NO2

P-PO4

Reference

Mussel farm

0

0.5

1

1.5

2

2.5

3

3.5

Sep-06 Oct-06 Nov-06 Dec-06 Jan-07 Feb-07

µM l-1

N-NH4N-NO3

Reference

Mussel farm

In december 2006 the lower DOC in mussel farm is accompanied bya higher concentration ofnutrients, i.e. phosphates, nitritesand ammonia): higher degradation rate in mussel farm

In general the data show animpact of mussel farm on waterquality parameters

1- Impacts of mussel farms on sediments

Biopolymeric Carbon

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0M

3 - s

ept0

6

T21

- sep

t06

M3

- dec

06

T21

- dec

06

M3

- feb

07

T21

- feb

07

M3

- may

07

mg

C g-1

Carbohydrates_waterCarbohydrates_EDTALipidsProteins

5.9%38.5%

5.1%

4.4%

5.4%

6.2%9.2%

(Chl-a %)

Sediments show a general higher content of Biopolymeric carbon (also LOM) in the mariculture site

2- Trophic interactions: effects on plankton communities

M3(mussel farm)

T21(reference site)

Abundance of phyto and microplankton species evauated in the 4 samples(sept06, dec06, feb07, may07) in water samples collected inmussel farm (M3), inreference site (T21).

0%

5%

10%

15%

20%

25%

30%

35%

0% 5% 10% 15% 20% 25% 30% 35%

Relative abundance in Reference site (T21)

Rel

ativ

e ab

unda

nce

in m

usse

l far

m (M

3)

Is this a direct effect of mussel selective filtration?

1:1 line

Phytoplankton speciesabundance

0.0%

20.0%

40.0%

60.0%

80.0%

100.0%

0.0% 20.0% 40.0% 60.0% 80.0% 100.0%

Relative abundance in water (M3)

Rel

ativ

e ab

unda

nce

in M

ytilu

s

_

2- Mussel selectivity of plankton species

Indifferentspecies

Sele

cted

spe

cies

Rejected species

Comparison of the relative abundance of phyto and microplankton species in waterfrom mussel farm (M3) and in gut of mussel (50 each season) should evidence selectivity of mussels on each plankton species (phyto & micro).

Bacteriastrum delicatulum

Coscinodiscus spp.

Nitzschia spp

Pennate indeterminate

Prorocentrum minimum

Dec-06

Cyclotella spp.

Prorocentrum micans

.0% 20.0% 40.0% 60.0% 80.0% 100.0%

May-07

Prorocentrum micans

Pennate indeterminate

Pseudo-nitzschia seriata Chaetoceros spp.

0.0%

20.0%

40.0%

60.0%

80.0%

100.0%

0.0% 20.0% 40.0% 60.0% 80.0% 100.0%

Feb-07

Prorocentrum micans

Prorocentrum compressum

Peridinium quinquecorne

Pennate indeterminate

Navicula directaLeptocylindrus

danicusChaetoceros spp.

0.0%

20.0%

40.0%

60.0%

80.0%

100.0%Sep-06

Rel

ativ

eab

unda

nce

inM

ytilu

s

Selected species:Prorocentrum micansProrocentrum compressusPeridinium quinquecorneNavicula directa

Rejected species:Chaetoceros spp.Leptocylindrus danicusPseudo-nitzschia seriataNitzschia spp.

No selection:Pennate indeterminateCyclotella spp.

Relative abundance in water

Phytoplankton

2- Mussel selectivity of plankton species

3- Production performances: mussel growth Experimental measure of growth:monthly biometric measurements on 2cohorts displaced in a dedicated area of a mussel farm (M3).50 individuals each month for each cohort

length (mm); Width (mm);total wet weight (g ww)shell free wet weight (g ww)dry weigth (g dw)

Sep Oct Nov Dec Jan Feb Mar

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g dw

Sep Oct Nov Dec Jan Feb Mar

0.5

1

1.5

2

g dw

Dw – cohort juveniles

Dw – cohort adults

Feces

Respiration

Somatic growth

Pseudo-feces

Filtration

Ingestion

Assimilation

Seston

MaintenanceRespiration

Useful energy

Somaticinvestment

Gonads

Investimentreproduction

Gamets

Emission ofgametes

3- Bioenergetic model of mussel physiology

TPM

IngestionfI(TPM)

T

Respirationfm(T)

POM/TPM

Assimilation

fA(TPM, POM)

T

Filtrationfa(T)

POM

ClearencefCR(POM)

⎩⎨⎧ >⋅

=therwise 0

0 IF o

wwg dd &&&

γ⎪⎩

⎪⎨⎧ ≥≤≤−

= therwise

& F supinf

ow

ICICTT TIgww threshspawnspawn

[ ] 1)()()()(),()1(2maxmax

M

ndOm

mdCRaIPOMAd wTfRwPOMfTfCRTPMfETPMPOMfw

εεα ⋅⋅⋅⋅−⋅⋅⋅⋅⋅⋅⋅−=&

3- Bioenergetic model of mussel physiology

Juveniles cohort

Adults cohort

Dry

wei

ght

(g)

Dry

wei

ght

(g)

Calibration parameter:Maximum clearence rate (CRmax) and fraction into gonads (γ).

Forcing:TSMPOMChlorophyllTemperature(local data)

The model runs on length,wet and dry weight basis by using allometric scaling factors.

Bootstrap allowed obtaining distribution of estimated parameters (Crmax, γ).

Spawning periods

3- Annual flows associated to mussel farms

ANABOLISM

Feces

FILTRATION

Pseudofeces

consumo energia

INGESTION

ABSORPTION

650 tonC (1,18 1010 kJ)

TOTAL WEIGHT mussels

356 tonC (6,46 109 kJ)

Energy consumption

294 tonC (5,34 109 kJ)

3220 tonC (4,48 1012 L)

1880 tonC

RESPIRATIONGROWTH GONADS

Energy investment

6124 ton ww

Energy intake SESTON(TPM)

1340 tonC

1230 tonC

Montecarlo:virtual population of theGulf of Trieste composed by different individuals(different Crmax and γ).Realistic seeding time (Sept) and differential harvesting (from May to Sept).

Annual flows for all the mussel farms of the Gulf of Trieste

The mussel farmed in the Gulf of Trieste derivedirectly from phytoplankton

104 tonC/year of the 3220 tonC/year filtered

3- Annual flows associated to mussel farms

Average Primary Production of the GoT:

42-53 gC m-2 year-1

(Fonda Umani et al., 1992)

Assuming area of influenceof 1 km from the coast:Total Primary Productionapproximately1160-1460 tonC year-1

Mussel farms consumeSlightly less than 10% of this production

Conclusions

ECOMADR Project

Mussel farming impacts on water quality:drecrease of Chl-a and Pheo, increaseDOM, modify degradation of OM in someperiods (see december 06)

Mussel farming produces increase of LOM in bottom sediments

Mussels are selective filter feeders: inducemodification on plankton communities but we need lab experiments for soft species(non detecteable in guts)

We set up a model that reasonably represent mussel growth on the basis of water column data (POM, TPM, Chl-a, T)

About 10% of the Primary Production of the Gulf of Trieste is estimated to be consumed by mussels

All this need to be studied deeperand linked together: in the next

project (starting Jan08)!

Thanks!

Istituto Nazionale di Oceangrafia e di Geofisica Sperimentale - OGSDept. Oceanography & Dept. BiologyTrieste, Italy

Berger P., Fabbro C., Falconi C., Frangipane G., Larato L.,Lorenzon S., Manno C., Trevisani S.

Doz M., Barbieri G., Kutin S.Lisert s.r.l cooperativaTrieste, Italy

Valli G., Negusanti J., Fonda Umani S., Del Piero D.Università di TriesteTrieste, Italy

ECOMADR Projecthttp://doga.ogs.trieste.it/doga/echo/ecomadr/

Odorico R., Tempesta M.Shoreline ScarlTrieste, Italy

Endorsed by