应用生态模型研究近海贝类养殖的可持续发展

Application of Ecological Model in Studing the SustainableDevelopment of Coastal Shellfish Culture

建立了一个贝藻混养生态模型 ,并应用于桑沟湾栉孔扇贝、太平洋牡蛎和海带混养生态系统的模拟。这一模型在个体生长模型的基础上模拟种群的生长情况 ;通过模拟不同播苗养殖和收获方式下的产量 ,以及不同混养方式对海洋生态系统的影响来确定养殖容量。采用该模型的研究结果表明 :当养殖密度分别增加到目前扇贝和牡蛎放苗量的 2倍和 15倍时总产量最高 (达到养殖容量 ) ,但单位面积产量和产量 /播苗比减少 ,因此效益是下降的 ;扇贝放苗量增加到目前的 15倍 ,牡蛎增加到 30倍时会导致养殖生产崩溃 ,同时生态系统也发生改变 :在目前养殖密度下 ,桑沟湾向黄海输出初级生产产品 ,但是当放苗密度增加到 15～ 2 0倍时 ,桑沟湾需要黄海向其输入初级生产产品。上述结果表明 ,该模型可以迅速模拟养殖生物量和生态系统的变化 。

An ecological model for shellfish and kelp polycultur e is established and used to simulate the scallop, oyster and kelp polyculture e cosystem in Sanggou Bay. This model can simulate the population growth condition s based on the individual growth model, and the culture carrying capacity is det ermined by simulating the yields for different seeding and harvesting scenarios and the impacts of different polyculture modes on ecosystem. It is shown from th e simulated results that the total yield is the highest (reaching the culture ca rrying capacity) when the seeding densities for scallop and oyster increased to 2 times and 15 times those at present, respectively, but the harvest per unit ar ea and the ratio of harvest to seed are reduced, which shows a reduced productio n efficiency. Increasing the scallop seeding density to 15 times that at present or the oyster seeding density to 30 times that at present would lead to the col lapse of culture production. Meantime, the ecosystem in the bay would change gre atly, namely, there is a net export of primary production from Sanggou Bay to th e Yellow Sea under present seeding density conditions, but the bay would be a ne t phytoplankton importer when the seeding density increases to 15 to 20 times th at at present. It is shown from above study results that the model can quickly s imulate the changes in cultured biomass and ecosystem, and is an effective tool for polyculture management.