CHARACTERISTICS OF THE METAZOAN ZOOPLANKTON COMMUNITY IN XINGHU LAKE-A SOUTHERN SUB2TROPICAL LAKE

Xinghu Lake is a typical shallow lake located in the southern sub2tropical region of Guangdong Province, South China, and it comprises five basins, namely, Bohai, Li, Zhongxin, Xiannü and Qinglian1It has been eutrophic since the late 1990’s1In order to understand the response of zooplankton community structure to eutrophication, metazoan zooplankton, including rotifers, cladocerans and copepods, were investigated in 2002 in the lake177 taxa of metazoan zooplankton were observed1The metazoan zooplankton species were mainly composed of eurythermal ones and only a few thermophil ones were also found1The abundance of zooplankton ranged from 7152 ind1/L to 1505 ind1/L, and it was the highest in Bohai, namely 814199 ind1/L on aver2 age1Among three groups, rotifers dominated in the number of species, abundance and biomass, and the dominant genus was Brachionus1The abundance of rotifers in Bohai, reached 360124 ind1/L, was the highest in the four investigated basins, corre2 sponding to its highest trophic status1Copepods were the second dominant group1Nauplii and copepodites contributed more than 85% to the total abundance of copepods, and they had higher abundance in July and August1The dominant species were Mesocyclops thermocyclopoides and Thermocyclops taihokuensis1 Cladocerans were mainly composed of Bosmina longirostris and Bosminopsis deitersi1 The very low abundance of cladocerans and adults of copepods in the four basins was probably related to fish predation1In comparison with the data about zooplankton in the lake in 1996-1997, the abundance and biomass of metazoan zooplankton decreased significantly in 2002, and the crustacean changed into smaller2sized species1In contrast to the other lakes with similar trophic status in the northern sub2tropical region of China, the abundance and biomass of rotifers, cladocerans and copepods were much lower in this southern sub2tropical shallow lake1Although the lake is located far from the Equator, its meta2 zoan zooplankton community is similar to those typical lakes near the Equator1