Summer flounder (Paralichthys dentatus) trophic ecology in a eutrophic, polyhaline mid-Atlantic coastal lagoon system

Abstract

Tidal-dominated lagoons of the mid-Atlantic region serve as nursery habitats for summer flounder (Paralichthys dentatus), but information is scarce on the trophic ecology of the species in such systems. Summer flounder (3.8–25.2 cm TL) diet was assessed using samples collected seasonally (June 2011 to August 2014) from the Maryland Coastal Bays (MCBs). Summer flounder fed primarily on mysids, amphipods, annelids and isopods. Mysids contributed 53% by weight of P. dentatus stomach contents, and 52% of the stomachs contained mysids. About 63% of flounder consumed amphipods, which accounted for 36.3% by weight of the food consumed. In spring, amphipods contributed >50% of weight of flounder stomach contents in the Chincoteague Bay, whereas mysids (46.6%) were the most important prey in Newport Bay. Mysids (94.0%) and amphipods (98.5%) dominated the weight of stomach contents in Sinepuxent Bay and St. Martin River, respectively. Shrimp larvae (54.4%) and amphipods (30.0%) were the most important prey consumed in Assawoman Bay. In summer, flounder caught in St. Martin River, Assawoman Bay, and Sinepuxent Bay, consumed primarily mysids (>90% by weight); flounder from Newport (47.3%) and Chincoteague (15.6%) Bays consumed less mysids. Summer flounder diet in MCBs differs from the diet previously reported in the Chesapeake Bay, mainly because of the higher contribution of amphipods to, and negligible amounts of fish prey in the diets of, fish from the MCBs. These differences in diet probably result in a smaller mean size of fish at the end of their first year of residence in the MCBs.