温度与食物质量对太湖河蚬摄食及排泄的影响

Effects of Temperature and Food Quality on Corbicula fluminea Feeding and Excretion in Taihu Lake

河蚬(Corbicula fluminea)作为太湖大型底栖动物的优势物种,易受温度和食物质量等外界因素的影响,研究不同环境条件胁迫下的河蚬摄食及排泄变化,可为维护太湖生态稳定提供技术支持。室内模拟实验温度设置20~32℃的7个温度梯度处理组,河蚬食物分为藻华湖水、50%藻华湖水+50%绿藻、绿藻、50%绿藻+50%蓝藻、蓝藻共5种,通过温度与食物组合,测定不同条件下河蚬摄食率与排泄率,探究温度与食物质量对河蚬生存状态的影响。结果表明,温度对河蚬的摄食率具有显著影响(P<0.05),摄食率在20~24℃逐渐增至峰值后呈下降趋势;食物质量对河蚬的摄食率具有显著影响(P<0.05),表现为:绿藻>50%藻华湖水+50%绿藻>藻华湖水>50%绿藻+50%蓝藻>蓝藻;温度与食物质量对河蚬的摄食率具有显著的交互作用(P<0.05),且食物质量对其摄食的影响力会在高温胁迫下减弱。河蚬的排泄率会在食物质量较低的环境下增大,温度和食物质量对河蚬排泄具有显著的交互作用(P<0.05)。夏季高温期,河蚬的高能耗以及太湖蓝藻水华暴发造成的低质量食物,导致河蚬可用于生长和繁殖的能量锐减,可能是其种群衰退的重要原因之一。

Corbicula fluminea,the dominant species of macrobenthos in Taihu Lake,are very sensitive to external factors such as temperature and food quality.Investigation of changes in feeding and excretion of C.fluminea under different environmental conditions provides a theoretical basis for better understanding the ecological dynamics and stability of Taihu Lake.In this study,our aim was to identify factors leading to changes in C.fluminea populations.More specifically,laboratory experiments were conducted to investigate the single factor effects of temperature and food quality,and the effect of their interaction,on C.fluminea feeding and excretion.Seven experimental temperatures were set in the range 20-32℃(20℃,22℃,24℃,26℃,28℃30℃,32℃),along with five different food sources[(100%lake water),(50%lake water+50%Scenedesmus obliquus),(100%Scenedesmus obliquus),(50%Scenedesmus obliquus+50%Microcystis aeruginosa),(100%Microcystis aeruginosa)].The temperature and food quality interaction was investigated using different combinations of temperature(24℃and 32℃)and food quality[(100%lake water),(50%lake water+50%Scenedesmus obliquus),(100%Scenedesmus obliquus)].Results show that temperature had a significant effect on the feeding rate of C.fluminea;the rate gradually increased to a peak at 20-24℃and then decreased.Food quality also had a significant impact on the feeding rate of C.fluminea(P<0.05);lower food quality decreased the feeding rate,in the order(100%Scenedesmus obliquus)>(50%lake water+50%Scenedesmus obliquus)>(100%lake water)>(50%Scenedesmus obliquus+50%Microcystis aeruginosa)>(100%Microcystis aeruginosa).Further,the interactive effect of temperature and food quality had a significant effect on the feeding rate of C.fluminea(P<0.05);the effect of food quality on the feeding rate of C.fluminea decreased under the stress of high temperature.The excretion rate of C.fluminea increased in an environment with low food quality,and temperature and food quality had a significant interactive effect on the excretion of C.fluminea(P<0.05).The higher temperatures in summer lead to higher energy consumption,during the time that cyanobacteria blooms result in lower food quality.These two factors reduce the energy available to C.fluminea for growth and reproduction and are primarily responsible for the observed declines in C.fluminea population in Taihu Lake during the summer.