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2B - Natural stressors and toxicants (TU13/14) Effect of food limitation on the sensitivity of Daphnia magna exposed to fenvalerate. Pieters, Barry1, Reynaldi, Sebastian1, Liess, Matthias1, 1 UFZ - Centre for Environmental Research, Leipzig, Germany ABSTRACT- The outcomes of environmental risk assessments may be questionable if results are merely based on the effects of the toxicant, and interactions with natural stressors are not considered. Individuals in natural populations are regularly exposed to these natural stressors who may alter the concentration responses to toxicants. Especially food limitation is considered as a distinctive feature occurring regularly in aquatic biological systems. The occurrence of toxicants in aquatic systems in combination with restrictive food conditions, therefore, necessitates an in depth evaluation of the possible additional risks of these contaminants. Thus, standard 21-day reproduction tests were performed with individuals of the cladoceran Daphnia magna under high and low food conditions, pulse exposed to the pyrethroid insecticide fenvalerate. The results of this study demonstrated that according to the food level the mortality, growth, reproduction and individual recovery time were altered. Hence, it is suggested that such information should be included in higher-tier risk assessments in order to gain better interpretation of potential risks and reduce uncertainties. Key words: food limitation, multiple stressors, recovery, Daphnia magna |
