丹江口水库底栖动物群落次级生产力空间分布

Spatial Distribution of Macrobenthic Secondary Production of Danjiangkou Reservoir

于2007年7月—2008年5月,分季度对丹江口水库底栖动物群落及水环境进行为期一年的调查。运用经验公式估算丹江口水库大型底栖动物群落的生产力,并分析底栖动物密度、生物量、生产力及P/B系数的空间分布,探讨环境因子与底栖动物群落生产力空间分布的关系。结果显示,丹江口水库底栖动物年平均密度、生物量及生产力分别为4 761 ind·m^(-2)、1.61 g DM·m^(-2)和35.45 g DM·m^(-2)·y^(-1),P/B系数为22.0 y^(-1)。不同区域生产力差异很大,湖泊区达61.80 g DM·m^(-2)·y^(-1),而支流区仅有5.48 g DM·m^(-2)·y^(-1)。P/B系数同样在湖泊区达到最大,为34.0 y^(-1);在丹江过渡区最低,为13.1 y^(-1)。颤蚓是生产力的主要贡献者,周年生产力为31.85 g DM·m^(-2)·y^(-1),占总生产力的90%。湖泊区由于其稳定的水动力条件,为颤蚓提供了非常适宜的生境,因此具有很高的生产力水平。与之相反,支流区由于水体扰动较大,底栖动物生物量及生产力水平均较低。从生产力的角度研究丹江口水库底栖动物群落的空间分布规律及影响因子,对丹江口水库的生态管理具有参考价值。

A year-long seasonal survey of macroinvertebrate community and environmental variables in Danjiangkou Reservoir was conducted from the July 2007 to May 2008. The annual macrobenthic secondary productions were estimated with empirical models,and the annual mean density,biomasses and P/B ratios were also calculated for spatial distribution analysis. Annual mean density,biomass and annual production were 4 761 ind.·m^（-2）,1.61 g DM·m^（-2）,and 35.45 g DM·m^（-2）·y^（-1） respectively,and P/B ratio was 22.0 y^（-1） in the whole Danjiangkou Reservoir. Mac-robenthic secondary productions among ecological zonations were evidently different. Annual production in lacustrine zone was up to 61.80 DM·m^（-2）·y^（-1）,and was only 5.48 DM·m^（-2）·y^（-1） in the tributary zone. P/B ratio was also highest（34.0 y^（-1）） in lacustrine zone but lowest（13.1 y^（-1）） in Danjiang transitional zone. Tubificidae contributed to the most macrobenthic secondary production in Danjiangkou Reservoir,whose annual production was 31.85 g DM·m^（-2）·y^（-1）,taking 90% of the total value. The stable aquatic environment and abundant sediment organic matter supplied the Tubificidae with suitable habitat,which consequently resulted in the high production and P/B ratio in lacustrine zone. In contrast,because of the strong water disturbance,advantages for the Tubificidae were decreasing in tributary zone and transitional zones,so were the productions and P/B ratios. It is of great significance to study the spatial pattern of secondary production and its impact factors in Danjiangkou Reservoir. This study has reference value for ecological management of Danjiangkou Reservoir.