The diets of larval gulf menhaden Brevoortia patronus, spot Leiostomus x d n t h u~s , and Atlantic croaker Micropogonias undulatus, collected in the northern Gulf of Mexico in December 1979, February and December 1980, and February 1981, were significantly (P<0.001) different when compared with respect to length by step-wise discriminant analysis, and there was little overlap when the diets of size-specific larvae that CO-occurred in discrete collections were compared by percentsimilarity. Gulf menhaden larvae had a more diverse diet that included phytoplankters (diatoms and dinoflagellates) as well as zooplankters (tintinnids, pelecypods, pteropods, and all stages of copepods). The diets of larval spot and Atlantic croaker were largely restricted to zooplankton. Overall diet distinctiveness, the lack of diet overlap, and the lack of small-scale CO-occurrence indicate that the larvae of these three species do not compete for food.

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When spot Leiostomus xanthurus larvae began to feed (age 3 d at 24øC, 4 d at 22øC, 5 d at 20øC, 5-6 d at 18øC), little endogenous energy was available to them. If food was withheld 3 d or more, most larvae died even if food then became available. Larvae were equally vulnerable to starvation throughout the prefiexion stage (-<3.8 ram standard length, the stage occurring before the upward flexion of the notochord tip). Later-stage larvae (flexion and postflexion, during and after notochord flexion, respectively) survived food deprivation significantly longer than prefiexion-stage larvae. Discriminant analysis of six body measurements (standard length, head length, eye diameter, body depth at anus, body depth at cleithral symphysis, body depth at pectoral fin base) identified significant changes in larva body shape during starvation and successfully classified larvae according to nutritional condition. Moderately starved and starved (food withheld for 1-2 and 3-4 days, respectively) prefiexion larvae were morphologically similar, indicating that the effects of starvation proceeded rapidly. Fed and moderately starved (food withheld for 1-4 days) fiexion-postfiexion larvae were morphologically similar, indicating that starvation of older larvae proceeded more slowly. The proportion of prefiexion larvae correctly classified improved when starved and moderately starved fish were combined into a single category (83% correctly classified); classification of fiexion-postfiexion larvae improved when fed and moderately starved fish were combined (87% correct).

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Eelgrass (Zostera marina), an important component of estuarine areas from Nova Scotia to North Carolina, is the primary habitat for the economically important bay scallop (Argopecten irradians). The bay scallop fishery in North Caxolina is extensive yet precarious in its dependence on seagrass systems. A balance between habitat integrity and scallop harvest is necessary to sustain the fishery. In this study, we examined the effect of scallop dredging on eelgrass meadows. When the eelgrass was in its vegetative stage, 15 and 30 dredgings were carried out in a hard sand substrate and a soft mud substrate and the results compared to an area of no dredging. Impact was assessed by analyzing the effects of scallop harvesting on eelgrass foliar dry weight and on the number of shoots. The hard bottom had significantly greater overall biomass of eelgrass (P < 0.01, ANOVA) than the soft bottom but fewer differences were apparent for eelgrass shoot density (P < 0.10). Increased dredging led to significantly reduced levels of eelgrass biomass and shoot number (P < 0.01) on both hard and soft bottoms. Harvesting of bay scallops in North Carolina occurs at a time of seasonally low eelgrass foliar biomass, peak abundance of commercially harvestable scallops, and settlement of post‐larval scallops that require eelgrass leaves for attachment. Onr data demonstrated potentially negative impacts on the scallop fishery that would result from harvest‐related damage to existing eelgrass meadows.