PREDATION ON MUD CRAB MEGALOPAE, PANOPEUS-HERBSTII EDWARDS,H MILNE - EFFECT OF HABITAT COMPLEXITY, PREDATOR SPECIES AND POSTLARVAL DENSITIES

Laboratory experiments were conducted to evaluate the magnitude of pre dation on megalopae of the Atlantic mud crab, Panopeus herbstii H. Mil ne Edwards, in four simulated habitats (salt marsh bottom, shell botto m, seaweed patch and sand bottom). Predators included juvenile blue cr abs (Callinectes sapidus Rathbun), common killifish (Fundulus heterocl itus (L.)) and grass shrimp (Paleomonetes pugio Holthius). Experiments were run at two different densities of megalopae. Two-way analysis of variance revealed significant effects of predator type and substratum . Proportional mortality was lowest on shell bottom, and blue crabs we re the least effective predators, regardless of habitat. Additionally, proportional mortality was lower at low megalopal densities than at h igh megalopal densities. Decreased predation at low megalopal abundanc e may afford density-dependent modulation of mud crab populations.