Projects
23: Gonad malformations in whitefish (Coregonus lavaretus) in Lake Thun: are they induced by endocrine disruptors?
Whitefish populations from Lake Thun show a high prevalence of gonad malformations. The triggering factor(s) of this phenomenon are not known yet. This project will investigate whether endocrine disruptors play a role in the development of these malformations.
Segner Helmut, Universität Bern
e-mail: helmut.segner@itpa.unibe.ch
Background
In Lake Thun, whitefish (Coregonus lavaretus spp.) with various alterations of gonad morphology have frequently been observed since 2000. Affected individuals are present in all age classes, in both sexes, and in all three ecomorphs of whitefish living in Lake Thun. Single cases of gonad alterations in whitefish have also been reported from other lakes, both in Switzerland and worldwide. However, the situation in Lake Thun appears to be unique with respect to the high prevalence of the alterations and the remarkable diversity of the anomalies. Although we have currently no evidence for the cause(s) of the malformations, it has been speculated that they may be induced by endocrine disruptors originating from ammunition deposited on the bottom of the lake.
Aim
This project aims to evaluate whether endocrine disruptors play a role in the development of the gonad malformations in whitefish from Lake Thun. The project will investigate (1) whether gonad malformations as seen in the field population can be induced by exposing whitefish to lake water or lake sediments, or by feeding the fish with zooplankton from the lake. This will be studied with long-term rearing experiments. (2) whether endocrine disruptors occur at biologically effective levels in the Lake Thun ecosystem (water, sediment, food organisms). We address this question with bioanalytical and chemical analytical methods. The results from the project will allow us to confirm or reject the hypothesis of a causative role of endocrine disruptors in the formation of the gonad malformations in whitefish of Lake Thun.
Significance
Fish are an important indicator of an intact lake ecosystem. The appearance of gonad malformations creates concern about a potential toxic contamination of the lake ecosystem. Since Lake Thun is one of the larger resources of drinking water in the Canton of Berne, the presence of harmful substances in Lake Thun is not only relevant to the ecosystem but also to human health. The clarification of a potential impact of endocrine disruptors on the lake and the whitefish populations is therefore of considerable importance.