Vulnerability of newly settled red drum (Sciaenops ocellatus) to predatory fish: is early-life survival enhanced by sea grass meadows?
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Predation experiments were conducted to evaluate the vulnerability of red drum larvae and early juveniles to pinfish predators. Experiments were designed to analyze the effects of habitat complexity, prey size, and rearing condition on prey vulnerability. Three structurally different habitats were simulated in experimental mesocosms. Instantaneous hourly mortality rates for hatchery-reared red drum were significantly higher in the unvegetated habitat than in either shoal grass or turtle grass. A similar trend in predation mortality was observed for wild-caught red drum. Mortality rates for hatchery red drum were higher than for wild individuals in all three habitats; however, the differences were not significant. Predation mortality decreased increasing prey size, suggesting that small red drum were most vulnerable to predators. It was concluded that habitat complexity is critical to the survival of newly settled red drum, and changes in the complexity or aerial coverage of natural sea grass meadows may affect early-life survival and possibly recruitment levels.