FACTORS INFLUENCING THE DISTRIBUTION, ABUNDANCE AND GROWTH OF LYNGBYA-WOLLEI IN CENTRAL FLORIDA

Fifteen sites in the Kings Bay/Crystal River estuarine system, Florida , were sampled over 1 year to determine the spatial and temporal distr ibution and abundance of the filamentous blue-green alga, Lyngbya woll ei (Farlow ex Gomont) Speziale and Dyck. Monthly biomass (dry weight) of benthic Lyngbya mats was constant at approximately 1 kg m(-2) durin g most of the year, but it decreased from April to July when large mat s were observed floating on the water surface. Multiple regression ana lyses showed that Lyngbya biomass was correlated negatively with condu ctivity and alkalinity; this is consistent with L. wollei being primar ily a freshwater species. In regions of the bay with higher salinities , the vascular macrophyte, Hydrilla verticillata (L.f.) Royle, prevail ed. Nutrient influences appeared to be small even though the northeast portion of Kings Bay/Crystal River has high concentrations of nitroge n, phosphorus and calcium. Controlled laboratory studies were conducte d to determine the effects of pH, salinity, and nutrients on growth of L. wollei. Optimal growth occurred at a pH of 8.0 and a salinity of 0 ppt (g 1(-1)); salinities in excess of 5.25 ppt killed more than 99% of the cells within 2 weeks. Growth of Lyngbya from five Kings Bay sta tions in six nutrient sources (spring water; NO3-N, NH4-N, PO4-P, NO3- N+PO4-P, and NH4-N+PO4-P) did not differ among stations, and nutrient additions produced no increases over spring water. Addition of Ca2+ in creased growth of L. wollei at low and intermediate concentrations of nitrogen and/or phosphorus; this partially explains why spring water, derived from the limestone aquifer, produces such good growth of lyngb ya.