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Secondary biological pump driven by food web interactions : A case study in Lake Biwa for gloval environmental issues

由食物网相互作用驱动的二次生物泵：琵琶湖全球环境问题的案例研究

基本信息

批准号：
08308031
负责人：
NAKANISHI Masami
金额：
$ 13.89万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

项目摘要

To understando responses of aquatic ecosystems to global environmental change, we studied biological and decomposition processes in relation to environmental variables such as nutrients, light and water temperature, and relations between sedimentation flux of biological products and food chains.1) Primary production of phytoplankton was limited by phosphorus in the layr above 5 m deep but by light intensity below 5 m deep. 2) Decomposition rate by bacteria was limited by phosphorus in the epilimnion and by water temperature in the hypolimnion.3) Sedimentation flux corresponded with 12% of daily production of phytoplankton and most of the phytoplankton production were consumed by zooplankton and bacteria in the epilimnion. 4) 20-30% of the sedimentation flux were assimilated by Amphipoda gammarid in the aphotic zone. 5) The sedimentation flux changed seasonally depending on precipitation and propagation of microplanktonic algae such as Fragilaria crotonensis.Biological production-decomposition rates and the sedimentation flux in Lake Biwa were strongly influensed by physical variable like light and water temperature, and food web structure. Further, they related closely to nutrients inflowing from rivers. These results suggest that climate change controlling precipitation, light, water temperature and nutrients influences directly acquatic ecosystems through processes of biological production-decomposition and vertical transportation of particulate organic matter.

为了解浮游植物对全球环境变化的响应，研究了浮游植物的生物和分解过程与营养盐、光照和水温等环境变量的关系，以及生物产物的沉积通量与食物链的关系。1）浮游植物初级生产力在5 m以上的水层受磷的限制，而在5 m以下的水层受光照的限制。2)表层水体中细菌对浮游植物的分解速率受磷的限制，而下层水体中细菌对浮游植物的分解速率受水温的限制。3）表层水体中的沉积通量相当于浮游植物日生产量的12%，浮游植物生产量的绝大部分被表层水体中的浮游动物和细菌所消耗。4)在无光区，端足类同化了20-30%的沉积通量。5)沉积通量的季节性变化取决于降水量和巴豆脆杆藻（Fragilaria crotonensis）等微生态藻类的繁殖，生物生产-分解速率和沉积通量受光照、水温等物理变量和食物网结构的强烈影响。此外，它们与河流流入的营养物质密切相关。这些结果表明，气候变化控制降水，光照，水温和营养盐直接影响水生生态系统通过生物生产分解和颗粒有机物的垂直运输过程。