THE EFFECT OF SAND AND LIGHT ON PREDATION OF JUVENILE PLAICE (PLEURONECTES-PLATESSA) BY FISHES AND CRUSTACEANS

Rates of predation on 0‐group plaice, Pleuronectes platessa. in aquaria were compared under four different combinations of conditions to test the hypothesis that the presence of sand in which they may bury affords a refuge from predators. The effect of light and darkness on predation rate was also examined, Two crustaceans, the shrimp, Crangon crangon, and the portunid crab, Liocarcinus holatus, and two fishes, cod, Gadus morhua, and pollack, Pollachius pollachius, were used as predators. Predaton rates were significantly higher in the dark for all predators except pollack. Predation rates in the absence of sand were signifcantly greater only for pollack. The results suggest that predation rates on plaice during their juvenile nursery stage on sandy beaches will be significantly greater during darkness than during the day. Burying in sand appears to provide only a partial refuge from predation, perhaps because natural predators have evolved effective methods of foraging for buried prey. Copyright © 1993, Wiley Blackwell. All rights reserved