We tested separately the effect of two taxonomically related rotifers (
B. patulus and
B. macracanthus) on the population dynamics of another species (
A. fissa) at low (0.5 ×10
6) and high food levels (1.5 × 10
6 cells/ml of
Chlorella vulgaris) using different inoculation densities (0–100%). We also quantified the impact of
A. fissa on the two brachionid species. Regardless of the presence of the competing species, an increase in the availability of food
led to increase in the abundances of the three rotifers. The population growth of
B. patulus, B. macracanthus, or
A. fissa was affected negatively when cultured together with another species. An increase in the initial density of any one of the
competing species became advantageous to maintain a certain population size. At a low algal food level,
B. patulus was able to suppress
A. fissa more strongly than
B. macracanthus. On the other hand, at a high food level,
B. macracanthus suppressed the population of
A. fissa more strongly than
B. patulus. Peak population densities for
A. fissa varied from about 150 to 1000 ind./ml, depending on food density and the presence of competitors. The rate of population
increase (
r) of
A. fissa, B. patulus, and
B. macracanthus increased with an increase in food availability but decreased with increasing initial density of the competitor. Both
Brachionus spp. experienced negative growth rates in the presence of
A. fissa, especially at a high initial density of the latter.
Published in Russian in Ekologiya, 2007, Vol. 38, No. 5, pp. 381–390.
The article was submitted by the authors in English.
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