台湾海峡微型浮游动物的摄食压力及其对营养盐再生的贡献

Grazing Impact of Microzooplankton in Taiwan Strait and Its Contribution to Nutrient Regeneration

于2005年3月台湾海峡的5个站位采样分析了微型浮游动物的空间分布,用稀释法研究了浮游植物的生长率和微型浮游动物对浮游植物的摄食压力,同时对微型浮游动物的氨氮产生率进行了推算.结果表明,各站微型浮游动物主要为红色中缢虫(Mesodinium rubrum)和以急游虫(Strombidiumspp.)为主的无壳纤毛虫,其次为异养甲藻-螺旋环沟藻(Gy-rodinium spirale)和砂壳纤毛虫.各类群在表层呈不均匀分布:红色中缢虫A6站最低,为425个/L,E2站达最大值,为27 125个/L,且在E2,E9和E13站占绝对优势,占微型浮游动物总量的84%以上;无壳纤毛虫丰度为203-5 025个/L,E13站最低,E2站最高;异养甲藻E9站表层没有分布,A6站达最大值,为463个/L;砂壳纤毛虫丰度为0-438个/L,F1站最高.垂直分布上,除A6站外,一般表现为表层多,中层和底层逐渐减少.表层浮游植物的生长率为0.36-0.50 d-1,微型浮游动物的摄食率为0.12-0.30 d-1,相当于每天摄食浮游植物现存量的11.09%-25.67%,初级生产力的28.38%-84.04%.利用微型浮游动物的摄食率推算其氨氮产生率为0.16-2.40 mg N/m3d,达到维持现场初级生产所需氮量的8.7%-28.1%.

Based on the dilution technique,the growth rate and morality rate of phytoplankton were studied at five stations in Taiwan Strait in March, 2005, the microzooplankton excretion of nitrogen derived from phytoplankton was also estimated. Microzooplankton was mainly composed of Mesodinium rubrum and aloricate ciliates, also including heterotrophic dinoflagellates and loricate ciliates,among which,Mesodinium rubrum was dominant,up to 425-27 125 ind/L in abundance,especially at E2,E9 and E13 station. The density of aloricate ciliates was 203 -5 025 ind/L at surface. Heterotrophic dinoflagellates and loricate ciliates were founded at every station,with the density of 0-463 ind/L and 0-438 ind/L at surface respectively. The vertical distribution of microzooplankton was generally more at surface water than in medium and in deep water. The growth rate of phytoplankton was 0.36-0.50 d^-1 and the morality rate was 0. 12-0. 30 d^-1. Microzooplankton grazed 11.09% -25.67 % of the phytoplankton stock or 28.38%- 84.04% of the primary production per day. Excretion of phytoplankton-derived nitrogen by microzooplankton varied between 0. 16 and 2.40 mg N/m^3d , which could potentially supply 8.7 -28.1 % of phytoplankton nitrogen demand.