A diver-operated encircling net was used to quantify diel variation in the fish fauna present in the tropical, Thalassia-dominated, seagrass meadow of Tague Bay, St. Croix. Diel variation in fish density was evident at the familial level, and for the major species found, accurately
represented patterns of feeding activity. Small, permanently resident grass bed fishes characterized the diurnal fish community with parrotfishes (Scaridae) and wrasses (Labridae) dominating. At night, grunts (Haemulidae), squirrelfishes (Holocentridae) and cardinal fishes (Apogonidae) were
the dominant active fishes. A twilight changeover, similar to that observed among fishes on coral reefs, marked the transition between these day and night seagrass fish communities. The seagrass bed served as an important feeding ground for coral reef fishes. Fifteen species (51% of the
nocturnal collection) moved from diurnal resting sites to feed over seagrass at night. More than 87% of these nocturnal visitors (10 species) were primary coral reef fishes, representing 79% of the fishes actively feeding in the grass bed at night. Resources of shelter and food, represented
by the coral reef during the day, and the seagrass meadow at night, respectively, were important in structuring this seagrass fish fauna.
The Bulletin of Marine Science is dedicated to the dissemination of high quality research from the world's oceans. All aspects of marine science are treated by the Bulletin of Marine Science, including papers in marine biology, biological oceanography, fisheries, marine affairs, applied marine physics, marine geology and geophysics, marine and atmospheric chemistry, and meteorology and physical oceanography.