Multiple environmental stressors confine the ecological niche of the rotifer .

The planktonic food web in extremely acidic mining lakes is restricted to a few species that are either acidophilic or acidotolerant. Common metazoans inhabiting acidic mining lakes with a pH below 3 include rotifers in the genera and . The life history response of to three environmental key factors, pH (2, 3.5, 5.0 and 7.0), temperature (10, 17.5 and 25 °C) and food concentration (10 000, 35 000 and 50 000 algal cells per mL), was investigated in a full factorial design using life-table experiments. The effect of each of the three environmental variables investigated on the rotifer life cycle parameters (life span, fecundity and population growth rate) differed. is a stenoecious species with a pH optimum in the range 3-4 and a comparably high food threshold. Combining the laboratory results with field data, we conclude that is severely growth limited in its natural habitat. However, low pH alone is not harmful as long as temperatures are moderate to warm and food is abundant. The population of in the field is maintained mainly due to release from competitors and predators.