“…The production of zooplankton is important to Great Lakes ecosystems, as zooplankton serve as a critical food resource to many fish species (Miller et al, 1990;O'Gorman et al, 1997;Fulford et al, 2006) and may also influence density and composition of phytoplankton (Makarewicz et al, 1998), which may in turn affect primary production and water clarity of the lakes (Scavia et al, 1986). Many species of zooplankton in the Laurentian Great Lakes, including cladocerans, calanoid copepods and cyclopoid copepods (Wells, 1960;McNaught and Hasler, 1966;Carter, 1969;Dorazio et al, 1987;Schulze and Brooks, 1987;Barbiero et al, 2000;Pangle et al, 2007), undergo diel vertical migration, a behavior that is general to zooplankton in freshwater and marine systems (DeMeester et al, 1998).…”