Predation Risk Affects on Fish Foraging Decisions
This research focuses on determining the distributional patterns and foraging behaviors of mangrove fishes in seagrass beds in relation to their food availability and risk from predators (particularly sharks) to provide further insights into how animals will react to ecosystem changes, which has important implications for their management and conservation.
Project Overview
The nearshore habitat of Biscayne Bay, Florida, provides an opportunity to observe and test the combined effects of food availability and predation risk on fish habitat selection across their foraging landscape, from the mangrove-seagrass ecotone to adjacent seagrass feeding habitat. The present study focuses on: (1) examining the apparent nocturnal foraging decisions of gray snapper (Lutjanus griseus), great barracuda (Sphyraena barracuda), bluestriped grunt (Haemulon sciurus) and seabream (Archosargus rhomboidalis) across a distance gradient extending from mangrove-seagrass interface across adjacent seagrass feeding habitat; (2) determining if and how differences in food availability and predation risk across this gradient influence fish distributions; and (3) testing if the observed patterns of fish distributions are predicted by classic foraging models. This work is being accomplished by undertaking the following integrated field and laboratory studies: (1) stomach content analysis of target fishes to reveal nearshore trophic linkages; (2) seine and gill net surveys to determine the nocturnal distribution and abundance patterns of the target fishes, their prey and their predators; (3) field manipulation experiments to explore gradients in predation pressure; and (4) model simulation to evaluate the effects of variations in food availability and predation risk on habitat selection by fishes across a subtropical marine ecotone.
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Nocturnal Fish Distribution, Feeding, and Predation Risk in Relation to a Mangrove-Seagrass Ecotone.
The combined effects of food availability and predation risk on foraging fish habitat use have been investigated via both laboratory and field experiments in contrasting habitat patches, primarily in temperate freshwater systems. In contrast, relatively little attention has been directed towards fish foraging decisions at subtropical marine ecotones.