Evaluation of Aquatic Macroinvertebrates Available to Wintering Waterfowl in Managed and Natural Wetlands in Western Tennessee

Aquatic and wetland invertebrates are important protein sources for wintering waterfowl in the Lower Mississippi River Alluvial Valley (LMAV). Few studies have evaluated winter invertebrate abundance patterns in the LMAV, particularly in Western Tennessee. I examined aquatic macroinvertebrate biomass, density, and diversity in beaver ponds, moist soil units and flooded, harvested soybean fields in Western Tennessee. Moist soil units and flooded soybean fields are common wetland practices on public lands in Western Tennessee. Beaver ponds offer natural habitat that is greatly increasing in the southeastern United States (Arner and Hepp1989). The objective of this study was to compare invertebrate abundance and biomass of selected invertebrate groups in wetlands important to wintering waterfowl in Western Tennessee. Three beaver ponds at Ames Plantation, three moist soil units and three flooded soybean fields at Chickasaw and Lower Hatchie National Wildlife Refuges were randomly chosen for intensive study. Monthly samples were collected from January to March in 2003 and 2004 with a benthos core sampler (8.8 cm diameter x 10 cm depth). Invertebrates were counted and identified to family or lowest practical taxa and the density, diversity, and biomass of invertebrates were compared among months and habitat types. A total of 1,077 (2003) and 1,796 (2004) invertebrates were identified from 19 higher taxa and 34 families. Oligochaeta and Diptera were most common in all three habitats. Bivalvia were prominent in beaver ponds whereas Nematoda were highly prevalent in moist soil units and soybean fields. Mean invertebrate biomass in this study ranged from 0.9 g/m2 ± 0.2 g/m2 (x ̅ [sample mean] ± s.e.) in soybean fields to 4.7 g/m2 ± 1.6 g/m2 in beaver ponds. Density of invertebrates ranged from 464/m2 ± 10 m2 in moist soil units to 883/m2 ± 228 m2 in beaver ponds. No differences were detected for density or biomass among beaver ponds, moist soil units, and soybean fields. Generally diversity showed little difference, however, for the month of March, diversity was slightly lower in soybean fields than in beaver ponds or moist soil units. I could not identify one treatment that provided more invertebrate resources than either of the other treatments