Role of priority effects and habitat complexity in coral-reef fish communities (Bahamas, Australia).

摘要

Understanding the processes that influence the composition of animal communities is a central goal in ecology. Interactions between established residents and colonizing juveniles that affect the subsequent survival of juveniles may influence community composition. In a series of experiments on coral reef fish communities in the Bahamas and Australia, I tested whether and how interactions between colonizing juveniles and established residents, such as predators and territorial competitors, affected recruitment, and whether these interactions were modified by habitat complexity.; In the Bahamas, I factorially manipulated the presence and absence of resident piscivores and territorial damselfishes on 16 spatially isolated patch reefs and found that both groups had strong, species-specific effects on subsequent recruitment. In a second experiment, I tested whether the aforementioned effects of residents were due to direct interactions between residents and juveniles or were the result of differential juvenile settlement. This was accomplished by repeating the first experiment, except this time placing piscivores and damselfishes within cages to prevent direct interactions. I found no evidence for differential settlement, suggesting that effects of residents were due to direct interactions between residents and juveniles after settlement. In a third experiment, I cross-factored the presence and absence of piscivores and damselfishes with two levels of habitat complexity. I found that juvenile abundance was strongly influenced by prior residents and that effects of residents did not differ with habitat complexity. In contrast, the abundance of adult fish was strongly influenced by habitat complexity but not residents.; In Australia, I factorially manipulated the presence and absence of resident predators and potential competitors on 20 reefs to determine whether these fish communities were influenced by resident juvenile interactions comparable to those in the Bahamas. Results were similar to those obtained with the same experimental design in the Bahamas, indicating that priority effects may be a common feature of coral reef fish communities.; These studies illustrate the importance of both habitat complexity and interactions between resident fishes and newly settled juveniles in coral reef fish communities, and provide a means of qualitatively predicting the future composition of these communities based on their current structure.