MEPS 327:279-288 (2006)  -  doi:10.3354/meps327279

ABSTRACT: For newly settled coral reef fishes, survival advantages may be associated with specific early life history traits or condition levels that lead to differences in behavior. To identify physiological and behavioral characteristics associated with different condition levels, bluehead wrasse Thalassoma bifasciatum recruits were collected immediately after settlement from reefs in the upper Florida Keys, USA, and transported to the laboratory for experimental analysis. Quantification of swimming capabilities was coupled with otolith analysis to identify early life history traits associated with swimming performance. Fish with the highest critical swimming speeds were those that grew faster as larvae, had shorter pelagic larval durations, and were smaller at settlement, although these individuals represented only 10% of the total sample. To further investigate condition-associated behaviors, a feeding treatment established fish of 2 different condition levels for comparison. Recruits fed for 1 wk at higher levels grew faster, had greater standardized weight (Fulton’s condition factor), and swam faster than food-deprived recruits. In additional behavioral trials, high condition recruits evaded a simulated predator threat at faster speeds than the low condition recruits. High condition fish also exhibited less risk-taking behavior by sheltering more in the presence of a predator threat and consuming less food. For both high and low condition recruits, the number that sought shelter increased and food consumption rates decreased in the presence of a predator threat. These results link early life history traits and physiology with associated condition-based differences in behavior, likely underlying the observation that mortality in T. bifasciatum is frequently selective for condition.

KEY WORDS: Reef fish condition · Survival advantage · Early life history traits · Critical swimming speed · Juvenile behavior · Foraging · Predator evasion