Life history changes in the benthic cladoceran Chydorus piger induced by low concentrations of sediment-bound cadmium
ABSTRACT The effect of sediment-bound cadmium on several life history parameters of the benthic cladoceran Chydorus piger, was tested in the laboratory. It was investigated whether a test with C. piger is an ecologically realistic alternative for the Daphnia test applied to sediments. Therefore, a culture of C. piger was exposed to a control and five cadmium concentrations, equilibrated with natural detritus (0.036, 0.063, 0.26, 0.55 and 1.0 mmol/kg). Continuous records of growth and reproduction were made which took as long as 20 weeks. Longevity of C. piger declined markedly from 112 days to 20 days as cadmium concentrations increased. Intrinsic rate of increase and age at first reproduction (AFR) tended to be stimulated at very low doses but this effect was not significant. However, they were negatively influenced by moderate cadmium levels. While a significant cadmium effect was found for all traits investigated, the effective doses of cadmium varied strongly. C. piger was found to be even more sensitive to cadmium than for example Daphnia and Hyalella, naturally occurring cadmium levels in detritus being effective to C. piger. Experiments with a benthic cladoceran can therefore give important information about the ecological effect of cadmium and possibly other toxicants deposited in sediments.
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- "Moreover D. magna is not a common representative species for Dutch surface water. Therefore an additional surface water bioassay was developed and applied using the benthic Cladoceran Chydorus sphaericus, a useful and sensitive test species (Koivisto et al. 1992, Dekker et al. 2002, Bossuyt & Janssen 2005, Dekker et al. 2006). Chydorus sphaericus is one of the most common cladocerans in The Netherlands (Fig. 1). "
ABSTRACT: Routine chemical monitoring gives insight in the presence of contaminants in surface waters, but not in their joint ecological effects. Therefore ecological water quality is assessed with bioassays. Recently, a new bioassay using the chydorid Chydorus sphaericus has been developed. Working with smaller volumes, materials and being less time consuming than the traditional Daphnia magna test regarding the culture and experimental design, the 'Chydotox-test' shows a comparable sensitivity. The new Chydotox-test is a promising alternative for the existing Daphnia sp. acute immobilisation test (OECD 1984).
Technical Report: Normstelling voor bioassays
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ABSTRACT: Most of the thousands of substances and species that are of concern for environmental management will not be investigated empirically at ecologically relevant levels because of financial, practical, and ethical constraints. To allow risk assessment for these less well-known categories, we have developed a mechanistic model with classical equations from toxicology and ecology. The parameters are linked to well-known properties, such as the octanol-water partition ratio K(ow), acute lethal (body) concentrations, and organism size. This allows estimation of intrinsic rates of increase r and carrying capacity K over a wide range of substances and species. The model was calibrated with parameter values (micro +/- 95% confidence interval) obtained in reviews and validated by a meta-analysis with largely independent data from 200 laboratory experiments. For single substances, the 5 to 95% interval of the observations on intrinsic rates of increase overlapped with the range predicted by the model. Model and experiments independently indicated that population growth ceased below 1% of the acute median lethal concentration in about 5% of the cases. Exceptional values and possible explanations were identified. The reduction of the carrying capacity K was nearly proportional to the inhibition of the population growth r. Population-level effects of mixtures as estimated by concentration addition were confirmed by observations in the experiments. The impact of a toxicant and another stressor could generally be described by response multiplication, with the exception of cases with extreme stress. Data sets on population laboratory experiments are biased to metals and crustaceans. This field will benefit from empirical studies on chemicals, conditions, and species, identified as risky by the model. Other implications of the model for environmental management and research are discussed.Environmental Toxicology and Chemistry 10/2005; 24(9):2267-77. DOI:10.1897/05-122.1 · 3.23 Impact Factor