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EFFECTS OF ZOOPLANKTON GRAZING ON PHYTOPLANKTON COMMUNITIES IN ESCAMBIA BAY, FL
Citation:
Lores, E M., R S. Stanley, J M. Macauley, L M. Smith, E. M. Pasko, AND Jr Craven WG. EFFECTS OF ZOOPLANKTON GRAZING ON PHYTOPLANKTON COMMUNITIES IN ESCAMBIA BAY, FL. Presented at 15th Biennial International Estuarine Research Federation Conference, New Orleans, LA, Sept. 25-30,1999.
Description:
Studies of microheterotroph and meso-zooplankton grazing in nutrient enriched natural waters of Escambia Bay have been conducted for the past two years. These studies include experimental scale (1 l, 8 l, and 80 l) and lab/field comparisons. Sites for these studies include oligohaline and mesohaline regions of the Bay. Seasonal variations in influence of microheterotroph and meso-zooplankton grazing are described. Depletion of inorganic nutrients and production of chlorophyll a and particulate C and N were followed daily. Phytoplankton pigments were used as indicators of changes in the phytoplankton community composition. Preliminary results suggest that increased zooplankton density may shift the phytoplankton community toward a dominance by zeaxanthin producers, while reduced zooplankton density lead to increased dominance by fucoxanthin producers. Most of the added nutrients (15 |M N + 1 |M P) were depleted in less than 2 days in summer, however, much of the added N was still available after 7 days in March. Microheterotroph dilution experiments were used to determine the rate of microheterotroph grazing and intrinsic phytoplankton growth. These studies are important for understanding the effects of zooplankton grazers on the estuarine phytoplankton community.