Cyst-based toxicity tests.
XI. Influence of the type of food on the intrinsic growth rate of the
rotifer Brachionus calyciflorus in short-chronic toxicity tests
C. Belgis, G. Persoone-2003
Chemosphere, 50(3): 365-372
(from Current Contents- via
ISI Current Contents)
Abstract:
As important members of zooplankton communities worldwide, rotifers are used
extensively in ecotoxicological research. Chronic rotifer tests are,
however, dependent on live algal food which adds to the complexity, the
variability and the costs of these bioassays. To bypass the former problem,
experiments have been undertaken with the freshwater rotifer Brachionus
calyciflorus, to determine their intrinsic growth rate (r) when fed for 48 h
on a mixture of green algae (Raphidocelis subcapitata recently renamed
Pseudokirchneriella subcapitata) obtained from algal beads stored for
different periods of time, and other inert foods. All tests have been
performed in disposable multiwells, in 1 ml cups each inoculated with 1
rotifer freshly hatched from dried cysts. The majority of the growth tests
was performed in eight replicates.
The investigations revealed that microalgae from
algal beads stored for up to one year, in darkness, at 4°C, supplemented
with dried blue-green algae (Spirulina) gave satisfactory rotifer
reproduction. The intrinsic growth rates of the rotifers, were, however,
dependent on the storage time of the algal beads; the highests r's (0.7-0.8)
were obtained with algae from beads not older than four months. Growth tests
with combinations of P. subcapitata and other inert feeds revealed that the
enrichment food Selco used in aquaculture, also gave the same reproductive
output as the combination microalgae/Spirulina.
A rotifer growth experiment with 18 replicates showed
that the variation coefficient is below 20% when the tests comprise eight
replicates.
This study demonstrated that microalgae from beads,
supplemented by other inert food, open the door for a practical and
cost-effective short-chronic rotifer test, which is totally independent of
the culturing of both the test species and its live food.
(State University Ghent, Lab. Environmental
Toxicology and Aquatic Ecology, Plateaustraat 22, B-9000 Ghent, Belgium,
e-mail of G. Persoone: guido.persoone@rug.ac.be)