John Wiley & Sons, Ltd.

A mixture of environmental organic contaminants in lake sediments affect hatching from Daphnia resting eggs

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Despite the relevance of resting eggs for ecology and evolution of many aquatic organisms and their exposure to contaminants accumulating in sediments, ecotoxicological studies using resting eggs are vastly underrepresented. The author's established a method that allows them to perform exposure assays with resting eggs produced by the Daphnia longispina species complex, key species in large lake ecosystems. A mixture of organic contaminants previously detected in sediments of Lake Greifensee was selected to test the potential effect of organic contaminants present in sediments on the hatching process. Resting eggs were exposed to a mix of 10 chemicals, which included corrosion inhibitors, biocides, pesticides and personal care products, for a period of 15 consecutive days. Using an automated counting software the author's found a significant increase in hatching success in the exposed resting eggs vs. controls. Such an effect has not been reported from ecotoxicological assays with resting eggs so far. Possible mechanistic explanations as well as the potential implications on the ecology and evolution of aquatic species that rely on a resting egg banks are discussed. Observed increased mortality and developmental abnormalities for hatchlings in the exposure treatments can be explained by toxic contaminant concentrations. The authors' study results highlight the need for further studies assessing the effects of organic contaminants on resting egg banks and aquatic ecosystems. This article is protected by copyright. All rights reserved

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