ISSN:
1573-5117
Keywords:
Rotifer
;
Brachionus
;
Anuraeopsis
;
initial population density
;
competition
;
food level
;
population growth rate
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract We studied the outcome of competition between a large (Brachionus calyciflorus) and a small (Anuraeopsis fissa) rotifer species at five algal (Scenedesmus acutus) concentrations (0.5 × 106 to 40.5 × 106 cells ml−1) and with varying initial densities in mixed populations (100 to 0% of B. calcyciflorus or A. fissa), the combined initial biomass being 0.2 µg ml−1 in all test jars. Experiments were conducted at 28 ± 1 °C. Regardless of food concentration, B. calcyciflorus showed a greater increase in biomass than A. fissa, peak densities (mean ± standard error) at the lowest food concentration in the controls being 1.34 ± 0.31 µg dry weight ml−1 and 0.82 ± 0.08 dry weight ml−1, respectively. At the lower food concentrations, A. fissa displaced B. calyciflorus and vice versa at the higher food concentrations. At the intermediate food concentrations of 4.5 × 106 cells ml−1, B. calyciflorus outcompeted A. fissa only if its initial population density was three times higher. The rates of population growth in controls varied from 0.792 ± 0.06 d−1 to 1.492 ± 0.13 d−1 for B. calyciflorus and 0.445 ± 0.04 to 0.885 ± 0.01 for A. fissa depending on food level. When both species were introduced together, low food levels favoured higher abundance of A. fissa than B. calyciflorus, suggesting, in nature, it is likely that small Anuraeopsis colonize oligotrophic water bodies more successfully than larger Brachionus. The results also suggest that the outcome of competition depends not only on the size of the competing species and food availability but also on their colonizing density.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00025402
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