Crustacean Zooplankton Density and Biomass in Wisconsin Waters of Lake Superior 2001-2008

Abstract

Crustacean zooplankton play an important role in the Great Lakes’ aquatic food chains by serving as food for many species of larval fish and for adult planktivores including rainbow smelt, chubs, and ciscoes. Dramatic changes in the density and composition of the zooplankton communities of the lower Great Lakes have been observed since the 1960s. These changes have been linked to the effects of cultural eutrophication and the introduction of exotic species, including dreissenid mussels. Variations in zooplankton biomass have already led to changes in the production of many species of forage fish in Lakes Michigan and Lake Huron. Scientists are concerned that similar changes may occur in the other Great Lakes, including Lake Superior.