Ref ID : 1528
Guntram Weithoff and Norbert Walz; Influence of the filamentous cyanobacterium Planktothrix agardhii on population growth and reproductive pattern of the rotifer Brachionus calyciflorus. Hydrobiologia 313/314:381-386, 1995
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The population dynamics of B. calyciflorus was investigated using a green alga, Monoraphidium minutum, and a blue-green alga Planktothrix agardhii as food sources, separately and as mixtures. Growth rate (r), egg ratio (ER), and juvenile development time (Dj) were measured in the laboratory and mortality rate and embryonic development time (De) were calculated. With M. minutum, Brachionus showed a typical growth curve ('Monod-kinetics') dependent on food concentration. In contrast B. calyciflorus did not grow well on P. agardhii. With all food concentrations the measured growth rates were about r=0. At low food concentrations r was low with both food types, but the ER of B. calyciflorus was significantly higher with P. agardhii as food source. Furthermore the relative egg volume of females carrying one egg was higher with Planktothrix than with Monoraphidium. An addition of P. agardhii to M. minutum led to increasing growth rates. Highest growth rates were found with complementary food sources. High food concentrations of M. minutum shortened the juvenile development (Dj) time, but (Dj) was uneffected by different P. agardhii food concentrations. A mixture of both algae did not shorten (Dj) compared with M. minutum as single food. The calculated (De) was not effected by different food qualities but the calculated mortality was nearly 3 times higher with P. agardhii as food.