AQUATIC MACROINVERTEBRATE ASSOCIATION WITH WILLOW WETLANDS IN NORTHEASTERN MISSOURI

Maximum aquatic macroinvertebrate density and biomass was 1600 and 470 0 individuals/m(2) and 9 and 20 g/m(2) dry weight, respectively, in tw o Mississippi River black willow (Salix nigra) floodplain wetlands, in northeastern Missouri. Density was lower than in seasonally flooded m arshes and other forested wetlands characterized by dynamic hydrology. Biomass was comparable to that reported in other studies. Maximum den sity and biomass of invertebrates occurred in late spring, 6 to 8 mont hs following flooding, when water level was between 11 and 20 cm. Taxo nomic composition was similar to that in other detrital based, foreste d wetlands and was dominated by crustaceans (Isopoda and Amphipoda), m ollusks (Pelecypoda and Gastropoda), chironomids, and oligochaetes. Be cause study sites were deeply flooded (50-120 cm) during waterfowl mig ration, invertebrates were unavailable to dabbling ducks during fall, winter, and early spring.