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Title: A spatially resolved model of seasonal variations in phytoplankton and clam (Tapes philippinarum) biomass in Barbamarco Lagoon, Italy Authored by: Spillman, C.M., Hamilton, D.M., Hipsey, M.R., Imberger, J. Abstract:
Barbamarco Lagoon is a small lagoon in the Po River Delta, adjoining the Northern Adriatic Sea. It is the site of a commercially valuable clam (Tapes philippinarum) fishery. This study investigated the ecological dynamics within the lagoon and interactions with the adjacent coastal waters and riverine inputs by modelling both the lagoon and the Northern Adriatic Sea, using a dynamically coupled three-dimensional hydrodynamic-ecological model (ELCOM-CAEDYM) adapted to include the clam population. The clam model dynamically accounts for clam C, N and P biomass in the benthos through parameterisations for filtration, excretion, egestion, respiration, mortality, and harvesting, and allows for multiple size classes using a new population dynamics sub-model. Output from the coupled model is validated against hydrodynamic and water quality data collected during field campaigns and routine monitoring. Time scales of tidal flushing, primary production and clam grazing were investigated and show that the Northern Adriatic Sea is the dominant source of phytoplankton to the clam populations of Barbamarco Lagoon, with clam growth and phytoplankton biomass fluctuating concurrently. The impacts of clam grazing and waste production on water column nutrient concentrations and phytoplankton biomass were also investigated over both local and lagoon-wide scales. Effects of clam cultivation on nutrient concentrations and phytoplankton biomass were primarily localised, with minimal impact on lagoon-wide concentrations at current clam stocking levels due to strong tidal flushing. Clam populations were found to alter the cycling of nutrients in the system, causing the lagoon to become a net sink for particulate organic matter and to export dissolved organic matter to the adjacent sea via tidal flushing. Ecosystem health and sensitivity of nutrient cycles to clam cultivation are important considerations for the long term management and potential expansion of the fishery.
Reference: Spillman, C.M., Hamilton, D.M., Hipsey, M.R., Imberger, J., 2008, A spatially resolved model of seasonal variations in phytoplankton and clam (Tapes philippinarum) biomass in Barbamarco Lagoon, Italy, Journal of Marine Systems, , 79: 187-203 Keywords: Le Lagune del Delta Bel Po Full Paper: http://uwa.edu.au/paper2.PDF |
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