海洋浮游生态系统中小型浮游动物的生态功能

小型浮游动物在海洋生态系统中的作用,主要指有多少能量通过小型浮游动物传递到桡足类,从而比较沿"浮游植物→中型浮游动物"和"浮游植物+细菌→小型浮游动物→中型浮游动物"两条食物链到达中型浮游动物的能流大小.为达到这个目的,需要研究各个能流路径的传递效率,即能量在各个营养级(初级生产--小型浮游动物,细菌生产--小型浮游动物,小型浮游动物的生长率,小型浮游动物--中型浮游动物)的传递效率.综述了国内外对上述营养级传递效率的研究现状,以期为我国的同类研究提供参考.浮游植物初级生产力被小型浮游动物摄食的比例平均为每天60%～75%,大大高于桡足类对浮游植物初级生产力的摄食压力每天10%.海洋浮游细茵的二次生产力相当于初级生产力的30%.其中80%～180%被小型浮游动物摄食.小型浮游动物的毛生长率为30%～40%,生产力是初级生产力的21%～34%.在西班牙西北部沿海,桡足类每天摄食2%～51%小型浮游动物生产力.因此,桡足类通过微食物网摄食的能量是初级生产力的0.4%～17%,与桡足类摄食初级生产的10%处于同一量级.不考虑碎屑提供的能流,小型浮游动物对桡足类饵料的贡献为20%以上,甚至可高达50%.

Role of Microzooplankton in Marine Planktonic Ecosystem

Microzooplankton is heterotrophic planktons in the size range of 0 ～ 200 mm. They graze on the phytoplankton primary production and bacteria production. At the same time, they are food items of planktonic co-pepods. Role of microzooplankton in marine pelagic ecosystem is (1) the magnitude of energy transferred from microzooplankton to copepods and (2) the contribution of microzooplankton to the food item ( microzooplankton and phytoplankton) of copepods. The energy transfer efficiencies between every trophic level (primary production-mi-crozooplankton, bacterial secondary production-microzooplankton, microzooplankton growth efficiency, microzoop-lankton-mesozooplankton) should be studied. This paper reviewed the status of above mentioned energy transfer efficiencies in order to provide references to microzooplankton studies in China. About 60%～75% of Phyplankton primary production is grazed by microzooplankton per day. This value is significantly larger than grazing pressure by copepods ( 10% d~(-1)) . The secondary production of marine planktonic bacteria equals 30% of primary production. About 80% ～ 180% of the bacteria production was grazed by microzooplankton. The gross growth efficiency (GGE) of microzooplankton is 30% ～40%. Therefore, microzoopolankton production is 21% ～34% of the primary production. Copepods grazing pressure on microzooplankton production is 2% ～51% per day (north coastal Spain). Thus, energy flow from microbial food web to copepod should be 0.4%～17% of the primary production, which is in the same level with the contribution of primary production. If the contribution of detritus was not considered , microzooplankton contributed more than 20% ( some times as high as 50% ) of the copepod food ingestion. Marine planktonic food web is a complex system. More studies are needed to elucidate every details of the production and transfer efficiency of every trophic level and, in the case of microzooplankton, of every group.