Aquatic Invertebrate Ecology During a Simulated
Botulism Epizootic in a Sacramento Valley Wetland
Introduction
Aquatic invertebrates are important in waterfowl diets during late summer and fall (McGilvrey 1966, Sugden and Driver 1980, Pederson and Pederson 1983, Miller 1987, Gruenhagen and Fredrickson 1990) when botulism epizootics are most common (Rosen 1971). Avian botulism kills up to hundreds of thousands of waterfowl in California each year (Hunter 1970), and during epizootics, dead waterfowl often remain to decompose in wetlands.
Decomposing duck carcasses resulting from natural or disease mortalities may provide additional sources of food for birds and other wildlife. As waterfowl carcasses decompose, they may attract aquatic invertebrates through organic enrichment or by providing forage for scavengers and decomposers. The objective of our study was to evaluate whether or not decomposing waterfowl carcasses in the fall had an influence on numbers, biomass, and taxonomic composition of wetland invertebrates, and whether or not the presence of carcasses affected the aquatic invertebrate food supply for living waterfowl.
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