Abundance and seasonality of infauna and epifauna inhabiting a Halodule wrightii meadow in Apalachicola Bay, Florida

Abstract

The fauna inhabiting a Halodule wrightii meadow in Apalachicola Bay, Florida, was studied from March 1975 through Feburary 1976. The infaunal community was sampled by monthly coring. Fifty-eight species were recorded, averaging 35 species per month. A maximum faunal abundance of 104,338 organisms per m² in April was one of the highest infaunal densities recorded in the literature. Sixteen species accounted for 84% of the total numbers and 80% of the total biomass over the study period. Numerical dominants were Hargeria rapax, Heteromastus filiformis, Ampelisca vadorum, Aricidea fragilis, and oligochaetes. Biomass dominants were Tagelus plebeius, Neritina reclivata, Ensis minor, and Haploscoloplos fragilis. Life history notes are given for several dominant species. Epibenthic fishes and macroinvertebrates were sampled by monthly trawling. Twenty-three species of fishes (mostly juveniles) were collected near the coring site, with most species and individuals recorded during the months May through September. Bairdiella chrysoura, Orthopristis chrysoptera, and Lagodon rhomboides comprised 76% of the total fish numbers. Eleven species of macroinvertebrates were collected mainly in June and July. Callinectes sapidus comprised 61% of the total invertebrate numbers. It is postulated that the influx of juvenile fishes and crabs into the Halodule meadow in summer months leads to a coincident decline in infaunal population densities (number per m²) through predation. Infaunal biomasses are largely unaffected by these predators since the biomass dominants are large or deep-burrowing species.