基于水体交换能力的调水工程对底栖动物群落影响研究

Study on mechanism of water transfer project impacting on macrobenthos community based on water exchange capacity

水文条件的改变会引起水生态系统的波动变化,大型调水工程的实施会改变水生生物群落结构。本研究分别调研了南四湖和东平湖在调水工程实施前后一段时间的大型底栖动物群落结构,模拟分析了调水工程引起的湖泊水龄变化特征,从水体交换能力的角度探讨了大型调水工程对湖泊中大型底栖动物群落的影响。结果显示,调水工程运行一段时间后,东平湖中大型底栖动物群落在年尺度上从由小体型的水生昆虫类主导转变为由大体型的软体动物主导,南四湖中软体动物的优势在调水工程实施之后更加凸显。在季节尺度上,软体动物占比通常在调水期(非雨季)减小,而在非调水期(雨季)增大。调水工程的实施改变了湖泊水动力场特征,在年尺度上增强了湖泊水体交换能力,调水入流与入湖径流的叠加使湖泊水体的高流速时间变长,这不利于小体型物种稳定生长,进而导致在年尺度上大体型软体动物的占比逐渐增大。此外,调水工程的实施主要是提升了非雨季湖泊的水体交换能力,但增加调水后的非雨季湖泊水体交换能力仍然小于雨季,这也导致软体动物占比在调水工程实施前后均呈现在雨季减小在非雨季增加的规律。

Changes in the hydrological conditions cause the fluctuation of an aquatic ecosystem,and the operation of a large-scale water transfer project often changes the community structure of aquatic organisms.This study examines the community structure of macrobenthos in Nansi Lake and Dongping Lake before and after the implementation of a water transfer project.The characteristics of water age change caused by the project are simulated and analyzed,and the influence of such large-scale projects on the community of macrobenthos in the lakes is discussed from the perspective of water exchange capacity.The results show that on the annual scale,after the project’s operation for a certain period of time,a change in the macrobenthic community in Dongping Lake occurred from domination by small-size aquatic insects to domination by large-size molluscs,and the dominance of molluscs in Nansi Lake was more prominent.On the seasonal scale,the proportion of molluscs usually was decreased in the water transfer period(non-rainy season),and increased in the non-water transfer period(rainy season).The implementation and operation of the water transfer project has changed the characteristics of the hydrodynamic field in the lakes,and enhanced the exchange capacity of the water bodies on the annual scale.Superposition of the water transfer inflow and the river runoff into the lake causes a longer time of flows with high velocity in the lake,which was not conducive to the stable growth of small-size species and thus led to a gradual increase in the proportion of large-size molluscs on the annual scale.In addition,the project’s implementation mainly enhanced the water exchange capacity in the non-rainy season,but the capacity in the non-rainy season was still lower,even with an increased water volume being transferred,than that in the rainy season,which also caused a decrease in the proportion of molluscs in the rainy season and an increase in the non-rainy season before and after the implementation of the water transfer project.