Water Quality and Aquatic Macroinvertebrates in Three Types of Reference Limesink Wetlands in Southwest Georgia

Abstract

In SW Georgia, three wetlands types have been classified based on vegetation and soils: marshes dominated by herbaceous vegetation, open savannas with an overstory canopy of cypress, and forested swamps composed of cypress/hardwoods. We sampled 28 relatively unimpacted limesink wetlands for water quality at eight different times during 1997-98, and sampled invertebrates using a D-frame sweep net at early, mid, and late hydroperiod times during 1997. Water quality was similar in all wetland types upon initial inundation, but later in the hydroperiod marshes and savannas still had similar water quality that differed from swamps. Swamps had higher levels of dissolved inorganic carbon, NH₄-N, NO₃-N, and PO₄-P, low dissolved oxygen levels, and darkly stained water. We identified 121 different aquatic invertebrate taxa, with 40 taxa occurring in ≤10% of the samples. Marshes had higher density, taxa richness, and diversity than the other wetland types. Our findings suggests that vegetation is the most important factor in determining invertebrate assemblages and that marshes have more niches and a wider variety of food sources than the other wetland types. This study will be useful in assessing and restoring wetlands in the region, although more work is needed to understand the role of fire and hydrologic variation in these wetlands.