Spotted seatrout (Cynoscion nebulosus): Factors affecting juvenile distribution, microhabitat selection, and trophic interactions in the Banana River Lagoon and Mosquito Lagoon, Florida

Adult spawning, juvenile recruitment, growth, microhabitat selection, and diet of spotted seatrout (Cynoscion nebulosus) from Florida's Banana River Lagoon (BR) and Mosquito Lagoon (ML) were studied. Spawning occurred from April–September, when water temperatures were >24°C. Juvenile recruitment to grassbeds peaked in August and September. Juvenile densities and biomass were higher in ML, but growth rates were higher in BR. BR juveniles exhibited a clumped distribution, but a dispersed distribution in ML. Day of the year and water temperature explained the greatest amount of variability in juvenile seatrout abundance and biomass. Juvenile abundance and biomass were lower in the densest grassbeds, shallowest depths, and highest salinities.; Lab experiments showed juvenile spotted seatrout spent more time in sparse and moderately-dense seagrass than in bare sand only when a predator was present in the tank. Neither seagrass density was preferred over the other. Blade morphology selection trials (flat blades versus cylindrical blades) were equivocal. Juvenile seatrout spent 62–65% of their time in deeper water and 35–38% in shallower water (regardless of predator presence), but the differences between depth zones were not significant.; Smaller juvenile size classes of seatrout had lower gut fullness. Diurnal and nocturnal feeding were recorded, and gut fullness was greater for nighttime feeding than daytime feeding. The smallest juveniles consumed calanoid copepods and hippolytid shrimp, shifting to hippolytid shrimp and fish with ontogeny. The proportion of fish in the diet increased with growth. Gobies were the most common fish prey. Hippolytid shrimp were the most important dietary item overall. BR juveniles shifted away from copepods sooner than ML juveniles, and ate a greater proportion of fish. Nocturnally feeding juveniles ate hippolytid shrimp almost exclusively.; ANCOVA analyses found no differences between BR and ML juvenile spotted seatrout for body weight or jaw gape height, but jaw gape width was greater for ML juveniles.