FISH ASSEMBLAGES IN SEAGRASS HABITATS OF THE FLORIDA KEYS, FLORIDA: SPATIAL AND TEMPORAL CHARACTERISTICS

摘要

Seagrass beds of the Florida Keys National Marine Sanctuary (FKNMS) have global renown, yet their fish populations require study. A 24-mo trawl survey determined that Haemulon plumierii (Lacepede, 1801), Lagodon rhomboides (Linnaeus, 1766), Monacanthus ciliatus (Mitchill, 1818), and Eucinostomus spp. constituted nearly 70% of small-bodied fishes in FKNMS seagrasses. Mean abundance and species richness were significantly higher in areas containing larger, denser, and more structurally complex seagrass beds on the Gulf of Mexico side, especially in the middle and lower Keys, than in the sparser and less complex Atlantic seagrass beds, which are much closer to the Florida reef tract. There was limited seasonal variation in fish-assemblage composition. Abiotic factors (water temperature, salinity, and dissolved oxygen) appeared less important in defining assemblages than biotic characteristics (i.e., seagrass structure). The only prevalent, economically important reef-associated fishes using the seagrass beds as nurseries were H. plumierii, Lutjanus synagris (Linnaeus, 1758), and Lachnolaimus maximus (Walbaum, 1792). Many coral-reef-associated families were absent and most members of the locally important snapper-grouper complex (Lutjanidae and Serranidae) were captured infrequently. This may be attributable to distance from the reefs and also because some of these species inhabit seagrasses nocturnally and so were not collected by the diurnal trawling.