ABSTRACT
Selenium (Se) is a naturally occurring element that is essential to fish, but at sufficiently high concentrations can cause large-scale reproductive failure in fish populations. Many of the early studies that evaluated the chronic toxicity of Se to fish focused on aqueous exposures to inorganic selenite. Accordingly, aqueous Se concentrations resulting in toxicity to fish can be highly variable between sites and, therefore, tissue Se concentrations are a better indicator of Se toxicity to fish. This chapter provides background information on Se toxicity by summarizing field examples of Se impacts on fish populations and discussing Se bioaccumulation in fish. Mechanisms of Se toxicity in fish are then summarized, followed by a detailed review of Se toxicity studies in which Se concentrations were measured in fish tissue. Fish tissue-based Se thresholds are recommended. Se concentrations in fish, from both laboratory toxicity studies and monitoring in the field, have been measured in a wide variety of tissues.
