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Abstract
Constructed wetlands used for wastewater treatment emulate the appearance and function of natural wetlands. Many constructed wetlands have introduced fish as a biocontrol of mosquito populations to mitigate nuisance and potential disease issues. The most commonly introduced fish, Gambusia, is known to prey indiscriminately on macroinvertebrates and small vertebrates. Trophic cascades caused by fish predation on invertebrates have been shown to slow litter breakdown rates in streams. Slower decomposition rates in constructed wetlands may inhibit the wastewater treatment process. I designed an experiment that assessed the impact of Gambusia predation on macroinvertebrate communities and litter breakdown rates at a wastewater treatment wetland in Clayton County, Georgia. Results showed that Gambusia did not significantly affect invertebrate populations or litter breakdown rates and are likely not affecting the wastewater treatment process. Instead, water chemistry, specifically dissolved oxygen concentration, appears to more directly affect invertebrate populations and litter breakdown.