Life Cycles of Limnocalanus macrurus and Senecella calanoides, and Seasonal Abundance and Vertical Distributions of Various Planktonic Copepods, in Parry Sound, Georgian Bay

Abstract

The life cycles and vertical distributions of Limnocalanus macrurus and Senecella calanoides and the seasonal abundance and vertical distributions of adults of other planktonic copepods in Parry Sound, Georgian Bay, were determined from diurnal vertical plankton hauls taken on 14 occasions from June 19, 1967, through November 11, 1968. The most abundant cyclopoid copepod on most occasions was Cyclops bicuspidatus thomasi. Tropocyclops prasinus was common, particularly in summer and autumn. Mesocyclops edax and Cyclops vernalis were scarce. Cyclops bicuspidatus thomasi and T. prasinus were usually concentrated in the upper strata, T. prasinus seldom being deeper than 3 m during summer.The most abundant calanoid copepod was Diaptomus ashlandi. Diaptomus minutus and D. oregonensis were also common, but D. sicilis was rare. Diaptomus ashlandi and D. oregonensis occupied much the same depths in the metalimnion during the periods of thermal stratification but were deeper in spring and fall. Diaptomus minutus was concentrated mainly in the epilimnion even when thermal stratification was slight. Epischura lacustris and Eurytemora affinis were scarce. Limnocalanus macrurus was abundant and monocyclic, becoming adult in late spring but not spawning until autumn; older copepodites inhabited somewhat deeper strata than younger stages. Senecella calanoides was less abundant than L. macrurus but was also monocyclic, becoming adult in autumn and spawning almost immediately; all instars were usually found in deeper water than L. macrurus. The possibility that S. calanoides, because of its longer period of development, is better adapted to life in Parry Sound than L. macrurus is discussed.