Seasonal and Interannual Variability in Flatfish Assemblages in a Southeastern USA Estuary

Abstract

Although salt marsh tidal creeks are among the shallow coastal and estuarine habitats important to juvenile fish, little is known about the temporal patterns of their use by flatfish in the southeastern USA. We used a 12-year monitoring study to examine seasonal and interannual variation in juvenile flatfish occupation of a salt marsh tidal creek. Fishes were collected monthly with a 1-m beam trawl during the middle of ebbing tide near Savannah, GA. Flatfishes were the most consistently collected and numerous species obtained; we rarely obtained other fish in high number except for an occasional recruitment pulse of sciaenids. The six flatfish species collected were blackcheek tonguefish Symphurus plagiusa, bay whiff Citharichthys spilopterus, fringed flounder Etropus crossotus, summer flounder Paralichthys dentatus, southern flounder Paralichthys lethostigma, and ocellated flounder Ancylopsetta quadrocellata. Bay whiff was the only species consistently collected as new recruits (< 20 mm TL), accounting for 83% of all recruits obtained in the study. Flatfish were collected year-round, with bay whiff numerically dominating winter and spring assemblages and blackcheek tonguefish dominant in summer, leading to differences in seasonal assemblages. Flatfish assemblage composition did not exhibit a consistent trend across years but was related to temperature variation. For instance, flatfish assemblages collected in springs that followed unusually cold winters differed from those that followed mild winters, contributing to interannual variation in habitat use. Bay whiff growth was positively related to temperature, but was not related to the densities of conspecifics or total flatfish. Estuarine tidal creeks provide important settlement and nursery habitat for flatfish that partition habitat use temporally via seasonal and interannual variation, and these fishes can consistently dominate the composition of ichthyofaunal benthic recruits.