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.