Ref ID : 667
Suzanne Bosselmann; Population dynamics and production of Keratella hiemalis and K. quadrata in Lake Esrom. Arch.Hydrobiol. 90(4):427-447, 1981
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The production of Keratella hiemalis Carlin and K. quadrata (Muller) in Lake Esrom was estimated by the linear method. K. hiemalis occured from January to late May. It produced 386,000 ind./m2 from subitaneous eggs, whereas 1,778,000 ind./m2 hatched from resting eggs. Production of biomass was 0.12 gww m-2 (0.02 gww m-2) from subitaneous eggs, 0.45 gww m-2 by individuals from resting eggs, and an unknown amount of resting eggs. The estimates of production of K. quadrata, which occured from the end of June to January, were 63,000 ind./m2 (0.02 gww m-2) from subitaneous eggs and 71,000 ind./m2 (0.02 gww m-2) from resting eggs. During a descent of individuals of K. hiemalis toward the bottom in early May, the percentage of females with resting eggs was correlated to the density. Simultaneously the death rate was high, whereas the birth rate and turnover of biomass was low. Possible causal relations between these parameters are discussed.