DISSERTATION RESEARCH: Complex Effects of Humans and Piscivores on Fish Assemblages in a Speciose Tropical River

世界上大部分物种多样性位于热带和亚热带生态系统中，有必要更好地了解这些系统的生态，以帮助遏制生物多样性的丧失，并评估社区和生态系统一级对人为影响的反应。在这项研究中，我们将研究两个物种之间的相互作用，孔雀鱼和食人鱼，可能会使孔雀鱼更容易受到商业网捕的影响。我们假设食人鱼将孔雀鱼限制在近岸栖息地，在那里它们很容易被网民利用。在大规模(约500平方米)的实验区，我们将研究孔雀鱼在有食人鱼存在的情况下是否会进入较浅的水域。此外，我们将研究孔雀鱼的行为反应是否对较低的营养水平具有级联效应，即当孔雀鱼被限制在浅水时，捕食鱼组合的组成不同。实验操作将与景观规模的调查相结合，以检查孔雀鱼、食人鱼和这些物种的主要猎物的分布。这些数据将与广泛的胃内容物和同位素分析相结合，以提供物种丰富的热带河流中食物网络结构的详细信息。通过描述食物网络背景下的人类影响，我们努力提供对特定环境问题的预测能力，但仍允许一般性，这将拓宽食物网络生态的理论基础和应用。

Much of the world's species diversity is located in tropical and sub-tropical ecosystems, and a better understanding of the ecology of these systems is necessary to help stem biodiversity loss and assess community- and ecosystem-level responses to anthropogenic impacts. In this study, we will examine how the interaction between two species, the peacock bass and piranha, may render the peacock bass more susceptible to commercial net fishing. We hypothesize that piranha restrict peacock bass to near-shore habitats, an area where they can be readily exploited by netters. In large-scale (~ca. 500m2) experimental areas, we will examine if peacock bass move into shallower water in the presence of piranha than they otherwise would. Further, we will examine if the behavioral response of peacock bass has cascading effects on lower trophic levels, that is, composition of prey fish assemblages are different when peacock bass are restricted to shallow water. Experimental manipulations will be combined with landscape-scale surveys to examine the distribution of peacock bass, piranha, and the dominant prey of these species. These data will be incorporated with extensive stomach content and isotope analyses, to provide detailed information of food web structure in a species-rich tropical river. By describing human impacts within a food web context, we endeavor to provide predictive power regarding a specific environmental problem, yet still allowing for generality that will broaden the theoretical foundations and applications of food web ecology.