Fish and macrocrustacean use of submerged plant beds in tidal freshwater marsh creeks

Abstract

Fishes and macrocrustaceans (nekton) were sampled biweekly from mid-June through October 1985 from submerged aquatic vegetation (SAV) and during September 1985 from unvegetated areas of tidal freshwater marsh creeks. Nineteen species of fishes (6918 individuals, 3.068 kg preserved wet weight) from 9 famhes, and 3 species of invertebrates (12036 individuals, 1.577 kg preserved wet weight) were collected from SAV The most abundant species were grass shrimp Palaemonetes pugio, banded killifish Fundulus diaphanus, mummlchogs F. heteroclitus, bluespotted sunfish Enneacanthus gloriosus, and mud crabs Rhithropanopeus harrisj:. Recruitment of small juvenile fishes of several species coincided with the period of greatest SAV area1 cover (late June through September). Average densities of fauna were significantly greater in SAV than over nearby unvegetated creek bottoms in September. Fauna1 abundance was not significantly related to SAV biomass, perhaps because the structural complexity of the SAV in our study area was high and nekton were abundant when SAV was present at low densities (i.e. low biomass). The numerically dominant species that occurred in SAV at low tide and on the marsh surface at high tide were similar Grass shrimp, banded lullifish, mummichogs and bluespotted sunfish accounted for > 90 % of the total number of organisms collected in each of the 2 habitats, SAV and marsh surface. The SAV of tidal freshwater marsh creeks is probably most important as habitat for forage fishes. Young of recreational species such as bluegill Lepomis macrochirus and pumpkinseed L. gibbosus also occupy this habitat.