. California fish and game. Fisheries -- California; Game and game-birds -- California; Fishes -- California; Animal Population Groups; Pêches; Gibier; Poissons. October 17. Dissolved Oxygen (mg • I 1) FIGURE 11. Vertical distribution of Diaptomus franciscanus nauplii and copepodids, in relation to dissolved oxygen concentration at Station I, 2 May, 13 June, and 17 October 1978 (curves fitted by eye). Cyclopoid copepod population peaks occurred in August and September in Big Bear Lake. Cyclops vernalis was the dominant cyclopoid copepod at all stations. Macrocyclops albidus and Eucyclops agili
. California fish and game. Fisheries -- California; Game and game-birds -- California; Fishes -- California; Animal Population Groups; Pêches; Gibier; Poissons. October 17. Dissolved Oxygen (mg • I 1) FIGURE 11. Vertical distribution of Diaptomus franciscanus nauplii and copepodids, in relation to dissolved oxygen concentration at Station I, 2 May, 13 June, and 17 October 1978 (curves fitted by eye). Cyclopoid copepod population peaks occurred in August and September in Big Bear Lake. Cyclops vernalis was the dominant cyclopoid copepod at all stations. Macrocyclops albidus and Eucyclops agilis, two primarily littoral cope- pods, were present at Station VIII in late winter and early spring, but were not taken at Stations I and III. Orthocyclops modestus was present in the hypolim- nion at Stations I and III in late summer, but absent at Station VIII which was mixed to the bottom. We were unable to separate the early life history stages of cyclopoid copepods so no detailed accounts of life histories will be presented. Cyclops vernalis appears to have at least two generations per year in Big Bear Lake, a minor one in early summer and a major one in late summer. Annual differences in copepod dynamics could not be examined because of incomplete taxonomic determinations in 1977. Maximum cyclopoid copepod densities were about twice as high in 1978 as in 1977, but calanoid maxima were similar between years. Cyclopoid predation on calanoid nauplii and copepodids has been shown to be an important factor limiting Diaptomus populations (McQueen 1969, Confer 1971) and may have been significant in Big Bear Lake in 1978. CONCLUSIONS The zooplankton community of Big Bear Lake was typical of eutrophic sys- tems. The community was dominated for much of the year by the cladocerans, Ceriodaphnia quadrangula and Daphnia pulicaria. Littoral rotifers, cladocerans, and copepods were commonly collected in our zooplankton samples, reflecting the shallow, weedy conditions that characteriz
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