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The removal of apex predators is widely recognized to have broad ecological consequences for terrestrial and aquatic communities. In marine systems, the direct effects of fisheries exploitation include altering the community standing stock (biomass), species composition, and size- structure of the fish assemblage. Although the direct effects of fisheries exploitation are well documented, there is increasing evidence that the non-lethal effects of predation can also strongly influence the structure and function of ecological communities. In this dissertation I set out to increase our understanding of the effects of predators on coral reef fish assemblages by conducting a series of large-scale natural experiments across groups of Pacific islands spanning gradients of human population density and oceanographic productivity within four distinct geopolitical regions. My dissertation research reveals striking evidence for the effects of fisheries exploitation and oceanographic productivity on coral reef fish assemblages in three key areas. First, I found strong evidence that the effects of fisheries exploitation are not restricted to large-bodied species from higher-trophic levels but are realized throughout the entire fish assemblage and across multiple trophic groups. Importantly, I show that multiple forms of fisheries exploitation may be present on coral reefs, indicating the complex nature of coral reef fisheries. Second, I show strong evidence of biophysical coupling with gradients of oceanographic productivity and alterations in predatory fish abundance on the body condition, growth rates, maximum size, and longevity of coral reef fishes. I also observe a breakdown of natural coupling at inhabited islands, suggesting that local human impacts are capable of homogenizing life history traits of fishes even when strong environmental gradients are present. Third, I show that the trophic structure of coral reef fish assemblages are more tightly linked to changes in ocean

The removal of apex predators is widely recognized to have broad ecological consequences for terrestrial and aquatic communities. In marine systems, the direct effects of fisheries exploitation include altering the community standing stock (biomass), species composition, and size- structure of the fish assemblage. Although the direct effects of fisheries exploitation are well documented, there is increasing evidence that the non-lethal effects of predation can also strongly influence the structure and function of ecological communities. In this dissertation I set out to increase our understanding of the effects of predators on coral reef fish assemblages by conducting a series of large-scale natural experiments across groups of Pacific islands spanning gradients of human population density and oceanographic productivity within four distinct geopolitical regions. My dissertation research reveals striking evidence for the effects of fisheries exploitation and oceanographic productivity on coral reef fish assemblages in three key areas. First, I found strong evidence that the effects of fisheries exploitation are not restricted to large-bodied species from higher-trophic levels but are realized throughout the entire fish assemblage and across multiple trophic groups. Importantly, I show that multiple forms of fisheries exploitation may be present on coral reefs, indicating the complex nature of coral reef fisheries. Second, I show strong evidence of biophysical coupling with gradients of oceanographic productivity and alterations in predatory fish abundance on the body condition, growth rates, maximum size, and longevity of coral reef fishes. I also observe a breakdown of natural coupling at inhabited islands, suggesting that local human impacts are capable of homogenizing life history traits of fishes even when strong environmental gradients are present. Third, I show that the trophic structure of coral reef fish assemblages are more tightly linked to changes in ocean

Tropical marine nearshore environments are among the most complex and biodiverse ecosystems on the planet, providing an estimated 100 million people with coastal protection, career opportunities, and economic and natural resources. However, this habitat is threatened on a global scale, and is diminishing at an alarming rate as a result of anthropogenic impacts such as pollution, overfishing, habitat destruction, and global warming. These impacts jeopardize resident biodiversity, and make it critical for scientists to increase their efforts to study and protect these important ecosystems. Conventional study methods, such as SCUBA, focus only on depths shallower than 30m, leaving as much as 80% of the nearshore marine environment largely unexplored. This project aimed to conduct an assessment of the biodiversity of fishes found at Cocos Island, Costa Rica using SCUBA and the three-person submersible, Deep See. Quantitative and qualitative surveys of the transition zone down to 300m were completed to determine species richness at various depths.

Tropical marine nearshore environments are among the most complex and biodiverse ecosystems on the planet, providing an estimated 100 million people with coastal protection, career opportunities, and economic and natural resources. However, this habitat is threatened on a global scale, and is diminishing at an alarming rate as a result of anthropogenic impacts such as pollution, overfishing, habitat destruction, and global warming. These impacts jeopardize resident biodiversity, and make it critical for scientists to increase their efforts to study and protect these important ecosystems. Conventional study methods, such as SCUBA, focus only on depths shallower than 30m, leaving as much as 80% of the nearshore marine environment largely unexplored. This project aimed to conduct an assessment of the biodiversity of fishes found at Cocos Island, Costa Rica using SCUBA and the three-person submersible, Deep See. Quantitative and qualitative surveys of the transition zone down to 300m were completed to determine species richness at various depths.