Zooplankton Trophic State Relationships in Four Alabama–Georgia Reservoirs

ABSTRACT In a 16-month study of four Alabama-Georgia reservoirs, data were collected to relate the trophic condition of the reservoirs to the zooplankton density, biomass, composition, diversity and spatial and temporal distribution within the systems. With the Carlson trophic state index (TSI) and using chlorophyll a concentrations in the calculation, the trophic status of the lakes ranged from a TSI of 39 (mesotrophic) to 65 (highly eutrophic). Total zooplankton density (107 organisms L−1 to 1,590 L−1) and rotifer density (70 L−1 to 1,481 L−1) increased with lake trophy. Crustacean zooplankton density and biomass did not respond as clearly to the trophic gradient During the fall/winter months crustacean zooplankton biomass was greater in the mesotrophic lake than in the three eutrophic lakes. An estimated 36% of the crustacean zooplankton of the mesotrophic lake was greater than 500 urn in total length (TL) compared to a range of 11% to 20% in the three eutrophic lakes. Bosmina longirostris (200 μm to 5...