Dissertation Research: The Influence of Predation on Mayfly Assemblages: Comparative Studies in Neotropical Streams

人们对热带河流中捕食者的作用知之甚少。本研究将研究一系列委内瑞拉河流中的捕食者-猎物关系，在这些河流中，近距离发现了各种各样的捕食制度。为了调查捕食者对蜉蝣（蜉蝣目）的直接和间接影响，将在从天然无鱼到含有60种鱼类的溪流之间进行一系列比较研究。捕食者的直接影响将通过进行野外封闭实验来检验。野外实验将与蜉蝣漂移、捕食者数量和饮食数据相结合，以确定捕食者在控制猎物丰度方面的效果是否因捕食者密度和/或猎物再定居潜力而不同。捕食者的间接影响将在几种情况下进行研究。将比较不同地点间苍蝇在石头顶部漂移和活动的规律。电影摄影将用于探索捕食者在决定蜉蝣觅食的时间和地点的重要性，以及捕食者骚扰对觅食效率的影响。这项研究的发现将对有关捕食在构造生态系统中的重要性以及生物相互作用在热带和温带系统中的作用是否不同的一般问题产生影响。J. D. Allan教授和博士候选人A. S. Flecker完全有资格进行调查，这将带来重大的后勤和科学挑战。新热带河流生态学是生态学研究的一个重要领域。

Little is known about the role of predators in tropical rivers. This study will examine predator prey relationships in a series of Venezuelan streams, where a wide range of predation regimes are found in close proximity. In order to investigate the direct and indirect effects of predators on mayflies (Order:Ephemeroptera), a series of comparative studies will be conducted between streams that range from naturally fishless to others containing 60 fish species. Direct effects of predators will be examined by performing field enclosure/exclosure experiments. Field experiments will be coupled with data on mayfly drift, predator numbers and diet, to determine if the efficacy of predators in controlling prey abundance differs according to predator density and/or prey recolonization potential. Indirect effects of predators will be examined in several contexts. Diel patterns of mayfly drift and activity on stone tops will be compared between sites. Cinematography will be used to explore the importance of predators in determining both when and where mayflies forage, and the effects of predator harassment on foraging efficiency. Findings from this research will have bearing on general questions concerning the significance of predation in structuring lotic systems and whether the role of biotic interactions differs between tropical and temperate systems. Professor J. D. Allan and doctoral candidate A. S. Flecker are well qualified to conduct the investigation which will entail significant logistic and scientific challenges. The ecology of neotropical rivers is an important area for ecological research.