ECOLOGICAL PROCESSES UNDERLYING ONTOGENETIC HABITAT SHIFTS IN A CORAL REEF FISH

摘要: Distribution of mobile animals may reflect decisions on how to balance conflicting demands associated with foraging and avoiding predators. A simple optimality model predicts that should respond changes in mortality risk (μ) growth rate (g) by shifting habitats a way maximizes net benefits. In this study, field caging tethering experiments quantified habitat-specific rates risk, respectively, for three different sizes coral reef fish, Nassau grouper (Epinephelus striatus), during its juvenile tenure off-reef nursery habitats. These bracketed the size at which species undergoes an ontogenetic habitat shift from interstices macroalgal clumps (“algal habitat”) areas outside, or adjacent to, macroalgae other physically complex microhabitats (“postalgal habitats”). Experimental results were used cost–benefit analysis test following alternative (but not mutually exclusive) hypotheses: (1) (g); (2) juveniles minimizes (predation) (μ); (3) if trade-offs exist between maximizing minimizing ratio (μ/g). Results suggested small fish face trade-off living relatively safe algal achieving high postalgal The value μ/g was significantly lower than typically reside habitat, medium large Thus, use consistent “minimize hypothesis.” highlight behavioral responses ecological processes, such as changing predation body size, determine distribution patterns animals.