Teratogenic Deformity Index for Fish

Abstract

Excessive selenium can cause a wide variety of toxic effects in fish (see Chapter 3). The most prominent outwardly visible Symptom of selenium poisoning is teratogenic deformities. When observed in the field concurrently with elevated tissue selenium residues, terata can be used as an easily recognized, reliable indicator of selenium toxicity. Because of this characteristic, they are a useful tool for evaluating selenium hazards in aquatic ecosystems. However, a simple notation of the presence of deformities is not an assessment of mortality and Potential long-term impacts on fish populations. Such an assessment is needed to fully understand the level of ecological damage that has taken place. To make such an assessment, it is necessary to link the prevalence of terata with corresponding degrees of mortality. This linkage can be derived by examining laboratory and field studies that document teratogenic mortality in response to selenium exposure. I have reviewed that Information and used it to develop the Teratogenic Deformity Index (TDI) presented in this chapter. The TDI provides field verification of reproductive failure and assesses the magnitude of toxic impacts to current and future generations of fish. The examples presented illustrate how TDI is applied to fish population sampling data.