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，更好地了解这些系统的生态学对于帮助阻止生物多样性丧失和评估群落和生态系统对人为影响的响应是必要的。在本研究中，我们将研究孔雀鲈鱼和食人鱼这两个物种之间的相互作用如何使孔雀鲈鱼更容易受到商业渔网的捕捞。我们假设食人鱼将孔雀鲈鱼限制在近岸栖息地，在那里它们很容易被网虫利用。在大规模(~ca。500平方米的实验区，我们将检查孔雀鲈鱼是否会在水虎鱼存在的情况下迁移到较浅的水域。此外，我们将进一步研究孔雀鲈鱼的行为反应是否在较低的营养水平上具有级联效应，即当孔雀鲈鱼被限制在浅水中时，猎物鱼群的组成是否不同。实验操作将与景观尺度调查相结合，以检查孔雀鲈鱼，食人鱼的分布，以及这些物种的主要猎物。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食物网结构的详细信息。通过描述食物网环境中的人类影响，我们努力提供关于特定环境问题的预测能力，但仍然允许通用性，这将扩大食物网生态学的理论基础和应用。

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.