Size-fractionated plankton community respiration in Lake Taihu

Abstract

浮游生物群体分尺度估测方法在水生生态系统研究中应用越来越普遍,但大型浅水湖泊中不同尺度浮游生物群体研究鲜见报道.本文以太湖2002年10月至2003年9月的野外实测资料为基础,系统研究了不同尺度浮游生物群落的(R为浮游生物群体的平均直径,R ≥ 41μm,2μm ≤ R<41μm,R<2μm)呼吸率.结果表明,在太湖梅梁湾,R ≥ 41μm的浮游生物群体(主要是微囊藻群体)占优势,呼吸率占总呼吸率的70%以上,R<2μm的浮游生物(主要是浮游细菌)呼吸率占总呼吸率的18%左右;在太湖北部敞水区,R ≥ 41μm的浮游生物的呼吸率占总呼吸率的10%左右,R<2μm的浮游生物占优势,其呼吸率能占总呼吸率的65%以上.总体来看,梅梁湾中R ≥ 41μm的浮游生物群体特别是微囊藻群体呼吸率占优势,敞水区微型浮游生物特别是浮游细菌对总呼吸率的贡献很大.;Studies on the size fractions of plankton communities in large shallow lakes are rare. Here we report on size fractionated plankton communities from Lake Taihu based on bimonthly measurements in field from October 2002 to September 2003. Based on the diameter(R) of the plankton community we analyzed size fractions of R ≥ 41 μm, 2 μm ≤ R < 41 μm and R < 2 μm. The fraction larger than 41μm, represented mainly by Microcystis colonies, dominated in Meiliang Bay. The respiration of this fraction contributed over 70% to the total plankton community respiration, while the fraction < 2 μm(mainly bacteria) contributed about 18% of the total plankton community respiration. In the center of the lake, the plankton community with R ≥ 41 μm contributed about 10% to the total plankton community respiration, while the plankton community R < 2 μm contributed about 65% to the total plankton community respiration. For the whole lake, the plankton community with R ≥ 41 μm, particularly the Microcystis colonies, dominated total plankton community respiration in the northern part of the lake while bacterial respiration was most important in the center of Lake Taihu.