SEASONAL OCCURRENCE AND VARIATION IN STANDING CROP OF A DRIFT ALGAL COMMUNITY IN THE INDIAN RIVER, FLORIDA

Monthly collections of unattached, free-drifting macroalgae were made from September 1975 through August 1976 at three stations in a seagrass bed near Ft. Pierce, Florida. The most common species were Dictyota dichotoma, Acanthophora spicifera, Hypnea cervicornis, H. musciformis, and Spyridia filamentosa. Chondria tenuissima occurred as a winter-spring dominant. Seasonal changes in standing crop of these plants are described. Total algal biomass maxima occurred in spring and early fall when water temperatures ranged from 23 to 27 °C and light energy averaged 400 to 500 Langleys/day. Minimum total biomass occurred in summer. Frequency distributions of algal biomass were contagious in September and from January to May suggesting aggregated populations. Low randomness (p) values in the other months are suggestive of a regular distributional pattern. Problems involved in sampling this community are discussed and comparisons with other studies are presented. © 1979, Walter de Gruyter