TEMPORAL DYNAMICS OF ZOOPLANKTON COMMUNITY COMPOSITION AND MEAN SIZE AT LAKE WAUBERG, FLORIDA

Patterns of mean zooplankton abundance were observed during January—August 1998 in Lake Wauberg, Florida. Zooplankton size structure was evaluated from April— August. Total zooplankton density, cladoceran density, copepod density and rotifer density varied significantly among months (P < 0.01). Zooplankton abundance was lowest in January and February, peaked in April and May, then declined throughout the summer. Cladocerans peaked in abundance in May and were dominated by Daphnia, Eubosmina, Bosmina, and Diaphanosoma at varying times throughout the study. Mean length for cladocerans ranged from 0.30 mm to 0.52 mm depending on which genera dominated at any given time. Mean copepod abundance varied among months and was generally highest in spring. Mean copepod length did not vary significantly (P > 0.05) among months due to the dominance of nauplii (>70% by number). Mean rotifer density in May was significantly higher than all other months except April (P < 0.05) with Conochilus/Conochiloides (grouped together) and Brachionus comprising the dominant taxa. Rotifers ranged in size from 0.06 mm to 0.15 mm and monthly mean size was greatest in late summer due to the presence of larger-bodied rotifers. Our results suggest that Lake Wauberg is more characteristic of tropical systems containing smaller adult cyclopoid and daphnid species than those found in more temperate climates. Fish predation may also play a role in structuring the zooplankton community in Lake Wauberg.