杭州西湖湖底附泥藻群落

Epipelic Algal Community on the Bottom of West Lake, Hangzhou

杭州西湖在 ２０世纪 ４０年代湖底附泥藻群落以蓝藻门静水隐杆藻为优势，占 ９８％－ ９９％，而 ９０年代本次调查时发现随着水体富营养化底栖性的附泥藻群落由蓝藻型转变为以硅藻门放射针杆藻为优势的群落．根据１９９１年４月及１２月调查全湖各湖区该群落分为三个组合：（ １）放射针杆藻组合：外湖及北里湖，藻密度高，（ ３０２－ ５７５） ｘ １０_４个· ｇ^（-１）．放射针杆藻占总藻量的４１２％－５２８％．（２）凸腹脆杆藻－放射针杆藻组合：分布在西部三个湖区．藻密度低，仅为前一组合的 １１３或 １１８．（３）静水隐杆藻组合：仅存在于三潭印月内湖．

Epipelic algal community and phytoplankton community are' two correlative communities in the same ecosystem of West Lake, Hangzhou. In the 1940s, Aphanothece stagnina was a dominate species in the epipelic algal community, occupying 98% - 99% of the sediment in West Lake. Therefore forwarded a half centenary, following the eutrophication of the lake, the transparency of water decreased, and the decrement induced a corresponding succession of the epipelic algal community. The dominant species are changed from Aphanothe stagnina to Synedra berolinensis. The epipelic algal community in West Lake can be divided into 3 assemblages: (l ) Synedra berolinensis Assem.: Distributed in Waixihu and Beilihu area with relatively high algal density, 302 x 10_4-575 × 10_4 ind· g ^(-1) Synedra berolinesis is a dominant species, occupying 41. 2 % - 52. 8 % of total algal number in the assemblages. (2) Fragilaria construens var venter-Synedra berolinensis Assem.: Distributed in 3 lake areas which are located in the western part of the lake(Xilihu, Yuehu and Xiaonanhu). The algal density is 1/3 - l/8 of the first assemblage. (3)Aphanothece stagnian Assem.: Only exists in the inner lake on Santanyinyue island.