固城湖生物资源利用和富营养化控制的研究

STUDY ON BIORESOURCES UTILIZATION AND EUTROPHICATION CONTROL IN LAKE GUCHENG

于1989－1992年通过野外调查、室内试验、池塘模拟和数学模型等方法,研究江苏省固城湖的理化条件,初级生产生物生长及其有关因子,水草、藻和鱼、蟹间的相互关系,以及水草渔业利用对水质的影响等。结果表明,固城湖渔业增产潜力还很大；但河蟹和鱼类的放养对水草资源有影响,如果放养强度过大,会使水草全部消亡,将会对水质产生不良影响(浮游植物过量繁殖,水透明度降低)。从兼顾资源持续利用和富营养化控制角度提出了渔产量模式建议,可增加河蟹产量约1．5倍,总渔产量约12．5％。

Field survey, laboratory experiments, .pond simulated experimeflts and mathematical modelling were resorted to in this 1989 - 1992 study on the physico-chdrical and biological conditions, the production of primary produeers and its environmntal factors, the relationship between equatic macrophytes,phytoplankton, and fish /crab, and the effects of utilization of macrophytes on water quality in Inke Gucheng, Jiangsu Province.The results showed that the stocking of crab and fish has effects on water plants.Pond simulated experiments showed that in pond with low stocking density (0.23g /m2,pond No.2) of crab, the macrophytes decreased, but did not disappear as in the other two ponds (No.3 and No.4) with stocldng density higher than 1.75g /m2.The decrease or disappearence of macrophytes increased phytoplankton growth and lowered water transparency.The ecological model, a modified Lotka-Volterra mddel of biological competition, predicted that if the standing crop of fish and crab in this lake during springtime were higher than 2.5 g /m2, the macrophytes would not grow. Based on the macrophyte resources (4.12kg /m2), the model predicted a potential atmual fishery productivity of about 1600t and an annually averaged phytoplankton chlorophyll content of 3.69mg /m3, which is lower than the criterion (10mg /m3) for eutrophic state.From the point of view of the sustainable utilization of bioresources and eutrophication control, the authors suggest a fishery production pattern which could in crease the yield of crab to about 1.5 times and the total fishery yield by about 12.5%.