Ecological Structure in a West Indian Gorgonian Fauna

Publisher： University of Miami - Rosenstiel School of Marine and Atmospheric Science

ISSN： 0007-4977

Source： Bulletin of Marine Science, Vol.25, Iss.2, 1975-04, pp. : 248-258

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Abstract

This report summarizes observations of the species composition, distribution, and diurnal activity patterns of gorgonians on a West Indian patch reef under siltation stress. The study was conducted from an undersea habitat operated by the Puerto Rico Inter-National Undersea Laboratory. Fifteen species contribute significantly to the gorgonian fauna. Species diversity and equitability are high (H′ = 3.46 bits/individual; H′/H′_max = 0.88), and the cumulative area-diversity curve rises rapidly. The gorgonians appear to interpret their environment as stable, favorable, and spatially uniform in spite of the siltation stress. Gorgonians show a daytime peak in polyp extension at 1000 hours and a nocturnal peak at 2200 hours. The daytime peak is strongly correlated with light intensity and plankton availability. The nocturnal peak is probably associated with feeding on zooplankton. Species specific differences in diurnal activity patterns suggest niche separation and that the degree of dependence on zooxanthellae may vary considerably. Predation on gorgonians appears to be slight but increases maintenance energy requirements and could influence the course of competition.