OBJECTIVES To define the different water bodies in Alfacs bay.

1. Dynamic model to calculate the carrying capacity for bivalvegrowth in a coastal embaymentJoana Ibáñez Solé1, Montserrat Ramón2,3 and Margarita Fernández-Tejedor11. Institute for Food and Agricultural Research and Technology (IRTA), Sant Carles de la Ràpita, Spain2. Institut de Ciències del Mar (CSIC), Barcelona, Spain3. Instituto Español de Oceanografía (IEO), Palma, Spain Symposium on Integrating New Advances in Mediterranean Oceanography and Marine Biology. Barcelona, 25-29 November 2013

2. OBJECTIVES • To define the different water bodies in Alfacs bay. • Modeling the depletion of seston and chlorophyll through a zero-dimensional dynamic model (using the half-saturation coefficient, χk ). • Application of the ecophysiological models SFG and DEB. • To calculate thecarrying capacity of Alfacs bay for bivalve aquaculture.

3. ALFACS BAY - Characteristics • Positive estuarine circulation pattern of the water inside the bay. • Wide range of temperatures. • Shallow waters. • Changes in the characteristics of the bay according to whether the irrigation channels are open or closed.

4. Pycnocline identification T (ºC) Closed channels Density = 27.10 kg/m3 Opened channels Density = 24.71 kg/m3

5. SITUATION OF SAMPLING STATIONS INSIDE ALFACS BAY Latitude (º) Longitude (º) Main pattern of water circulation inside Alfacs bay. (Camp et al., 1987).

6. Density [kg/m3] Surface (0.5m) Bottom (range 2.5 – 6m)

7. Salinity [PSU] Surface (0.5m) Bottom (range 2.5 – 6m)

8. Chlorophyll [mg/m3] Surface (0.5m) Bottom (range 2.5 – 6m)

9. TRANSECTS SAMPLED IN THE BAY Latitude (º) Longitude (º) Entrance transect Dock transect Central transect

10. ENTRANCE TRANSECT Density, σt [kg/m3] Salinity [PSU] Mitad boca Serramar Faro Stability, E [rad2/m] Chlorophyll [mg/m3]

11. DOCK TRANSECT Density, σt [kg/m3]Salinity [PSU] Chiringuito Muelle Chlorophyll [mg/m3] Stability, E [rad2/m]

12. CENTRAL TRANSECT Density, σt [kg/m3]Salinity [PSU] Emisario Trabucador Central Stability, E [rad2/m] Chlorophyll [mg/m3]

13. ENTRANCE DOCK CENTRAL Salinity [PSU] 38.5 38.5 38.5 36.5 36.5 36.5 34.5 34.5 34.5 29.0 29.0 29.0 Chlorophyll [mg/m3] 64 64 64 26 26 26 12 12 12 0 0 0

14. Modelling depletion at the mussel farm Latitude (º) A C B Longitude (º) Beginning Point A Middle Point B End Point C

15. Sampling points at the mussel farm 2123.8m 2672.5 m

16. Beginning rafts (A) Depletion [mg/dm2] Middle rafts (B) Depletion [mg/dm2] Seston [mg/dm2] Seston [mg/dm2] Depletion [mg/dm2] End rafts (C) Seston [mg/dm2]

17. Depletion [mg/dm2] The whole farm 200 150 100 50 0 -50 0 20 40 60 80 100 120 140 160 180 200 Seston [mg/dm2] DEPLETION EQUATION: d( ) = 0.7465· : concentration of available seston

18. [mg/h] Winter Spring Summer Autumn Winter Spring Summer Autumn From A to B Eastern part From B to C Western part Total: From A to C Average

19. [µg/L] CR [L/h] Half-saturation coefficient Winter Spring Summer Autumn Winter Spring Summer Autumn In situ simulated data (Galimany et al.) Datos de campo Field data Datos in situ simulados (Galimany et al., 2009)

20. Models DEB and SFG application Rate of energy ingestion (J/day): Arrhenius temperature function: • SFG equations is the chlorophyll concentration Ingestion (mg/day): k is the half-saturation coefficient Standard ingestion function: DEB equations

21. Models DEB and SFG application • DEB equations Rate of energy ingestion (J/day): Arrhenius temperature function: • SFG equations is the chlorophyll concentration Ingestion (mg/day): k is the half-saturation coefficient Standard ingestion function:

22. Models DEB and SFG application Rate of energy ingestion (J/day): Arrhenius temperature function: • SFG equations is the chlorophyll concentration Ingestion (mg/day): k is the half-saturation coefficient Standard ingestion function: DEB equations

23. Models DEB and SFG application Rate of energy ingestion (J/day): Arrhenius temperature function: • SFG equations is the chlorophyll concentration Ingestion (mg/day): k is the half-saturation coefficient Standard ingestion function: DEB equations

24. Models DEB and SFG application Rate of energy ingestion (J/day): Arrhenius temperature function: • SFG equations is the chlorophyll concentration Ingestion (mg/day): k is the half-saturation coefficient Standard ingestion function: DEB equations

25. DEB Model application Field data Chloropyll (mg/m2) Px (J/day) Winter Spring Summer Autumn Winter Spring Summer Autumn Chl-a available In situ simulated data Px (J/day) Chloropyll (mg/m2) Winter Spring Summer Autumn Winter Spring Summer Autumn Chl-a available

26. DEB Model application Field data Chloropyll (mg/m2) Px (J/day) Winter Spring Summer Autumn Winter Spring Summer Autumn Chl-a available In situ simulated data Px (J/day) Chloropyll (mg/m2) Winter Spring Summer Autumn Winter Spring Summer Autumn Chl-a available

27. SFG Model application Field data Chloropyll (mg/m2) I/Cmi (mg/m3) Winter Spring Summer Autumn Winter Spring Summer Autumn Chl-a available In situ simulated data I/Cmi (mg/m3) Chloropyll (mg/m2) Winter Spring Summer Autumn Winter Spring Summer Autumn Chl-a available

28. SFG Model application Field data Chloropyll (mg/m2) I/Cmi (mg/m3) Winter Spring Summer Autumn Winter Spring Summer Autumn Chl-a available In situ simulated data I/Cmi (mg/m3) Chloropyll (mg/m2) Winter Spring Summer Autumn Winter Spring Summer Autumn Chl-a available

29. Carrying capacity of Alfacs Bay • Approximations • Mussel Mytilus galloprovincialis: The only consumer species. • Only the food availability (seston/chlorophyll) and temperature are considered as limiting factors. We omitted oxygen concentrations and other characteristics of the bay as limiting factors. • We considered the circulation of the water inside the bay as unidirectional. Results The mussel farm can have 117 rafts similar to the current ones. The bay, in its whole extension, is able to accommodate 253 rafts.

30. Conclusions • Difficulty for working in shallow depths. • Chlorophyll spots inside the bay in the central zone, farther from the bay’s mouth. • Pycnocline variation – opened channels/closed channels. • DR rate and CR rate are lower during the hottest months of the summer. • The Χk parameter for Alfacs bay is variable throughout the year due to the wide range of temperatures in the bay water.

31. Conclusions • DEB model application in Alfacs bay and to the mussel species Mytilus galloprovincialis has provided satisfying results and also allowed to observe an important dependence between uptake and temperature. • SFG model is not applicable in Alfacs bay because it does not give a correct dependence between temperature and ingestion. It does not reproduce the observations correctly. • We were able to calculate a first approximation of the carrying capacity for Alfacs bay. This approximation shows that Alfacs bay is able to accommodate 3 times more rafts than there exist nowadays.

32. INIA: RTA04-023-Estudio integrado de los factores biológicos y ambientales condicionantes de la producción de mejillón en las bahías del delta del Ebro. XRAq: Ecofisiologia del musclo en relació a les característiques ambientals de les badies del Delta de l’Ebre. Thank you!