Abstract

Small motile Invertebrate fauna associated to the Phanerogam leaves constitutes the principal source of food for first level carnivorous fishes which represent the main part of fish biomass, in the Thalassia testudinum seagrass beds in the Caribbean. This small motile fauna was studied, by day and by night, in two types of seagrass beds, respectively located near the coastal mangroves and seawards, near a coral barrier reef in the Bay of the Grand Cul-de-Sac Marin in Guadeloupe Island (Lesser Antilles). An epibenthic trawl with 2 mm mesh was especially designed to catch that fauna. On the whole, 58 families of invertebrates were collected. Factorial correspondence analyses showed that the structure of Invertebrate community differed in the two types of seagrass beds. Near the coast, the Invertebrate biodiversity was higher, in terms of numbers of families, in particular for the Crustacean phylum. Seawards, the gastropoda Cerithidae constituted the dominant group in the invertebrate community. Analyses also revealed that abundances, in numbers and biomass, were three to four times higher at night than during the day. These differences in abundance were attributed to night migration of Invertebrates from the dead leaves litter toward the erected leaves of T. testudinum.