Diel Vertical Migrations and Horizontal Distributions of Limnocalanus macrurus and Senecella calanoides (Copepoda, Calanoida) in Lakes of Southern Ontario in Relation to Planktivorous Fish

Abstract

Patterns of diel vertical migration of two copepods, Limnocalanus macrurus and Senecella calanoides, showed marked differences among four lakes in southern Ontario. We hypothesize that diurnal and nocturnal vertical distributions of these two species reflect their vulnerability to planktivorous fish, which may include alewife (Alosa pseudoharengus), lake whitefish (Coregonus clupeaformis), lake herring (Coregonus artedii), rainbow smelt (Osmerus mordax), yellow perch (Perca flavescens), trout-perch (Percopsis omiscomaycus), and rainbow trout (Salmo gairdneri). Horizontal distributions of the two copepods also differed among four lakes: during early summer both species occurred in much shallower waters in lakes with low transparency than in clearer lakes.