Diel Variation in the Structure of Seagrass-Associated Epibenthic Macroinvertebrate Communities

Abstract

Epibenthic macroinvertebrate community structure (species composition, numbers of individuals and species, and relative abundance distributions) were examined at 4 study sites in the northeast Gulf of Mexico (Apalachee Bay, Florida, USA). The relative abundance distribution changes with time of sampling (diurnal or nocturnal) because individual species become more or less numerically abundant in nocturnal samples. The number of individuals collected was significantly different between diurnal and nocturnal samples at 3 of the 4 study sites. The degree of day/night variation appears to be associated with habitat complexity (as defined by plant biomass and red algae volume) for number of individuals, but not for number of species, collected. The inadequacies and consequences of reliance on an exclusively diurnal epibenthic sampling program for a good representation of macroinvertebrate community structure are discussed.