Minimal algal food
requirements in the presence of protozoan prey for the rotifer Brachionus
calyciflorus
S.
Mohr, D. Gerten, R. Adrian-2002
Journal of Plankton Research, 24(7): 723-728
(from Current Contents)
Abstract :
As recent experiments demonstrated that protozoans
support reproduction of the rotifer Brachionus calyciflorus only in the
presence of algal prey, we addressed the question of minimal algal food
requirements in a mixed diet of algae and protozoans to ensure positive
growth of B. calyciflorus. In numerical response experiments, we determined
the algal threshold concentration for zero population growth of B.
calyciflorus when feeding on a pure algal diet of Monoraphidium minutum, and
on a mixed diet of M. minutum plus the ciliate Coleps sp. Under pure algal
and under mixed food conditions, a minimum amount of 0.3 µg carbon (C)
ml(-1) M. minutum was needed to ensure zero population growth of B.
calyciflorus. At lower algal concentrations, Coleps sp. was of low
nutritional value. However, when offered in conjunction with a concentration
of 0.8 µg C ml(-1) M. minutum, Coleps sp. contributed equally to the
reproductive success of B. calyciflorus as compared to a sole M. minutum
diet. Overall, Coleps sp. can be an adequate supplement in the diet of B.
calyciflorus if a sufficient amount of algal prey is available. However, at
times of low phytoplankton biomass, consumption of ciliates does not
necessarily confer a reproductive advantage for this rotifer.
(Fed Environm Agcy; Dept II 1 5; Schichauweg 58;
D-14191 Berlin; Germany, e-mail: silvia.mohr@mba.de)