横岗水库后生浮游动物群落特征

Metazoan zooplankton communities in a tropical eutrophic reservoir: Henggang Reservoir, Guangdong

横岗水库位于广东省东莞市,是一个富营养化水体,于2005年5月和11月对该水库后生浮游动物进行采样。该水库浮游动物具有种类少、丰度低的特点,在组成上以轮虫为主。两次采样共检到25种,其中枝角类4种,成体桡足类4种,轮虫17种。5月份,共检到15种,11月份有所增加,为20种。轮虫是主要的优势类群,5月份和11月份轮虫的平均相对丰度分别为82.8%和78.8%,以裂足臂尾轮虫、萼花臂尾轮虫和前节晶囊轮虫为主要优势种。其次是桡足类,5月份和11月份平均相对丰度分别为16.6%和19.9%,以无节幼体和桡足幼体为主,成体以舌状叶镖水蚤为优势种。枝角类相对丰度最低,5月份和11月份平均相对丰度分别仅0.6%和1.3%,以微型裸腹溞为优势种类·∮味锏淖槌伞⒎岫·和生物量均存在时间和空间上的异质性。5月份浮游动物平均丰度为242.6ind.·L-1,平均生物量为0.912mg·L-1,11月份浮游动物平均丰度为138.5ind.·L-1,平均生物量为0.317mg·L-1。从河流区到大坝区,浮游动物的丰度和生物量呈下降趋势,体现了水库中由水文和水动力学调节的浮游生物分布空间异质性。横岗水库中大个体的前节晶囊轮虫丰度较高,致使浮游动物生物量要高于浮游动物丰度相当的热带富营养化湖泊—星湖,但无论是生物量还是丰度要远低于温带富营养化湖泊。

Metazoan zooplankton was sampled in the Henggang Reservoir, a hypertrophic reservoir in Guangdong Providence in May and November of 2005. The results showed that the zooplankton was characterized by a few species with low abundance. 4 species of cladocera, 4 species of adult copepod and 17 species of rotifer were observed. The total species number in May and November was 15 and 20, respectively. Rotifer was the most common group. The mean relative abundances of rotifer in May and November were 82.8% and 78.8% respectively. The dominant species were Asplanchna priodonta, Brachionus calyciflorus and Brachionus diversicornis. Copepod was a less common group; its mean relative abundances in May and November were 16.6% and 19.9%, respectively. Copepod was composed mainly by nauplii and copepodid. Phyllodiaptomus tunguidus was the common species in adult copepod. Cladocera was the least common group; its mean relative abundances in May and November were only 0.6% and 1.3% respectively. Moina marocopa was the common species in this group. The composition, abundance and biomass of zooplankton had tempo-spatial heterogeneity in the reservoir. The mean abundance was 242.6 ind. L^-1 in May and 138.5 ind. L^-1 in November. The mean biomass was 0.912mg.L^-1 in May and 0.317 mg.L^-1 in November. The abundance and biomass of zooplankton tend to decrease from riverine to lacustrine, corresponding to the morphology and hydrodynamics of Henggang Reservoir. Compared with other waters, the high abundance ofAsplanchna priodonta in Henggang Reservoir lead to higher biomass of zooplankton than other tropical eutrophic lakes, such as Xinghu Lake, which had similar zooplankton abundance. However, both abundance and biomass of zooplankton in Henggang Reservoir were far lower than those temperate eutrophic reservoirs.