INFLUENCE OF FOOD AND PREDATION ON THE DEPTH DISTRIBUTION OF JUVENILESPOT (LEIOSTOMUS-XANTHURUS) IN TIDAL NURSERIES

Relative abundances of young-of-the-year (YOY) spot (Leiostomus xanthu rus) sampled by trawling in two tidal creeks on Masonboro Island, Nort h Carolina, were highest in the shallow creek margins. Abundances of b enthic invertebrates sampled by cores in one of the study creeks, were also maximal at the creek margin. Polychaetes associated with the cre ek margin composed the largest fraction of spot diets, indicating spot located in the creek margins were in the area of highest food availab ility. Spot predators sampled by trawling and seining were uncommon an d were primarily juvenile (75-200 mm total length) southern flounder ( Paralichthys lethostigma), hake (Urophycis spp.), and bluefish (Pomoto mus saltatrix). Large YOY spot experienced a size refuge from predatio n, as only small YOY spot were found in predator stomachs. In laborato ry experiments testing the effects of the presence of a predator, food , or both food and predators on the depth distribution of YOY spot, fo od had a stronger effect on spot distributions than predators The resu lts of field observations and laboratory experiments suggest food has the strongest effect on spot distribution in the field, and that food is relatively more important than refuge from predation to the nursery function of shallow estuarine habitats.