鄱阳湖鱼类群落结构及其时空动态

为系统阐明鄱阳湖鱼类群落特征及其影响因素,以便为鄱阳湖的鱼类资源保护及可持续利用提供理论依据,2010年4~11月对鄱阳湖鱼类群落空间差异和季节动态进行了调查。结果表明,共调查到鱼类72种,隶属于7目14科46属。在群落结构上,江湖洄游型鱼类占鱼类种数的25.00%,河流型鱼类占鱼类种数的19.44%,湖泊定居型鱼类占鱼类种数的55.56%。在空间结构上,沿岸带共采集到鱼类49种,其中鲫(Carassius auratus)、鲤(Cyprinus carpio)、鲇(Silurus asotus)、黄颡鱼(Pelteobagrus fulvidraco)等10个种类在数量上占优势;敞水区共采集到鱼类68种,其中刀鲚(Coilia ectenes)、鲫(Carassius auratus)、贝氏(Hemiculter bleekeri)、似鳊(Pseudobrama simoni)等10个种类在数量上占优势;沿岸带鱼类密度和生物量在各样点间存在显著差异。在季节变化方面,敞水区物种数和生物量在月份间存在显著差异。鱼类群落组成与环境因子的CCA分析发现,影响鄱阳湖沿岸带鱼类群落的环境因子为水温、支流影响、离长江距离和透明度,而影响敞水区鱼类群落的环境因子为离长江距离和透明度。

SPATIAL AND TEMPORAL VARIATIONS OF FISH ASSEMBLAGES IN POYANGHU LAKE

To evaluate the fish assemblages of Yangtze River connected lakes, spatial and temporal variations of fish assemblages in the littoral zone and open water of the Poyanghu Lake in the middle and lower basin of the Yangtze River were investigated seasonally from April to November 2010. Throughout the study, 72 species belonging to 7 orders, 14 families and 46 genera were collected. Lake resident species was the richest, accounting for 5556% of total fish species. River lake migratory species accounted for 2500% of total fish species. While riverine species was the least, accounting for 1944% of total species. We collected a total of 6 136 individuals, representing 49 species, with 10 species such as Carassius auratus, Cyprinus carpio, Silurus asotus, Pelteobagrus fulvidraco as the dominant species in the littoral zones. We collected a total of 6 136 individuals, representing 68 species, with 10 species such as Coilia ectenes, Carassius auratus, Hemiculter bleekeri, Pseudobrama simoni as the dominant species in the offshore areas. Fish density and biomass differed significantly among the sampling sites in littoral zone, while fish species richness and biomass differed significantly among the sampling seasons in open waters. As observed for littoral zone samples, fish density was the highest in W3 and the lowest in W4, fish biomass was the highest in W3 and the lowest in W5. As observed for open water samples, fish species richness was the highest in September and the lowest in April, fish biomass was the highest in November and the lowest in April. Associations between fish abundance and environmental variables were examined with canonical correspondence analysis, which is a weighted averaging method that directly relates assemblage data to environmental variables by constraining species ordination to a pattern that correlates maximally with environmental variables. Correlations between environmental variables and canonical correspondence analysis axes were used to assess each variables contribution. In the littoral zones, species environment correlation coeffcients for the first four pairs of axes (CCA 1-4) were 0853, 0789, 0781, and 0859, respectively. For the first four assemblage axes, cumulative percent variance of species data was 29%. In the open water, species environment correlation coeffcients for the first four pairs of axes (CCA 1-4) were 0864, 0. 0875, 0000, and 0000, respectively. For the first four assemblage axes, cumulative percent variance of species data was 55%. Canonical correspondence analysis indicated that the environmental factors shaping fish assemblages were different between the two zones: water temperature, tributary presence/absence, distance from main channel of Yangtze River and water transparency were the significant environmental factors in the littoral zones; while distance from main channel of the Yangtze River and water transparency were in the open water