Comparative Habitat Utilization by Estuarine Macrofauna Within the Mangrove Ecosystem of Rookery Bay, Florida

Abundance and biomass of juvenile and adult decapods and fishes in adjacent intertidal mangrove, seagrass, and open water habitats were compared using a quantitative drop sampler. Replicate samples were taken in each habitat in July, September and December 1988 and April 1989. Over all samples, fish densities were higher in non-vegetated, open waters (74% of the total caught) than in flooded red mangrove (Rhizophora mangle) prop roots or mixed seagrass beds (13% each). Spotfin mojarra (Eucinostomus argenteus) was the dominant fish collected among prop roots, yellowfin menhaden (Brevoortia smithi), scaled sardine (Harengula jaguana), and striped anchovy (Anchoa hepsetus) were most abundant in open waters, and bay anchovy (A. mitchilli) dominated the catch over seagrasses, although there were seasonal changes in dominant species. Shrimp densities were higher in seagrass habitats (74% of the total captured) than in open waters (22%) or among mangrove prop roots (4%). Habitat dominants were longtail grass shrimp (Periclimenes longicaudatus) and pink shrimp (Penaeus duorarum) in seagrasses, American grass shrimp (P. americanus) in open waters, and Florida grass shrimp (Palaemon floridanus) among mangrove prop roots. Over all samples, crab densities were higher in seagrass habitats (47% of those collected) than in open waters (33%) or mangroves (20%). Habitat dominants were blue crab (Callinectes sapidus), iridescent swimming crab (Portunus gibbesii), and redhair swimming crab (Portunus ordwayi) among seagrasses, green porcelain crab (Petrolisthes armatus) and flatback mud crab (Eurypanopeus depressus) in open waters, and broadback mud crab (Eurytium limosum) in flooded mangroves. On a monthly basis, among-habitat differences in density or biomass of major taxa did not exhibit any patterns, with the exception of shrimp which were always significantly more numerous in seagrasses than in one or both alternate habitats. Flooded red mangroves were, at times, utilized by both resident and transient fishes and crabs (but not by shrimps) at densities similar to those in seagrasses and open waters.