. California fish and game. Fisheries -- California; Game and game-birds -- California; Fishes -- California; Animal Population Groups; Pêches; Gibier; Poissons. Station 8 FRJRODFRJRC. DFRJROQFRJPO 1977 1978 1977 1978 FIGURE 2. Composition of benthos at Big Bear Lake Study sites, December 1976-November 1978. The dominance of oligochaetes in the macrobenthos is typical of eutrophic waters (Beeton 1961, Thut 1969). Oligochaetes generally increase in dominance in the benthos during the process of eutrophication (Wetzel 1975). Lake Erie provides an excellent example of the effects of eutrophicatio
. California fish and game. Fisheries -- California; Game and game-birds -- California; Fishes -- California; Animal Population Groups; Pêches; Gibier; Poissons. Station 8 FRJRODFRJRC. DFRJROQFRJPO 1977 1978 1977 1978 FIGURE 2. Composition of benthos at Big Bear Lake Study sites, December 1976-November 1978. The dominance of oligochaetes in the macrobenthos is typical of eutrophic waters (Beeton 1961, Thut 1969). Oligochaetes generally increase in dominance in the benthos during the process of eutrophication (Wetzel 1975). Lake Erie provides an excellent example of the effects of eutrophication on benthos com- position, particularly in relation to the increased dominance of oligochaetes. In 1930, Lake Erie was oligotrophic and the benthic community was dominated by the mayfly, Hexagenia, and oligochaetes comprised only about 1% of the ben- thos (Wright 1955); but by 1958 Lake Erie had become eutrophic and oligocha- etes comprised more than 60% of the benthic fauna (Beeton 1961). Extreme oxygen depletion, characteristic of eutrophic lakes, eliminates most benthic organisms other than oligochaetes. This is illustrated in a comparison of benthos composition in Big Bear Lake in 1977 and 1978. In 1977, the drought year, the lake mixed to the bottom through the summer, aerating the entire water column at all study sites except Station 1. Station 1, located in the deepest portion of Big Bear Lake, stratified and anoxia developed in the hypolimnion. During the period of stratification (June-September), oligochaetes represented 97-100% of benthic macroinvertebrates collected at Station 1, but chironomid larvae remained an important component of the benthos at the other sites. In. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original California. Dept. of Fish and Game; California. Fish and Game Commission; Cali
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