Avoidance by olfaction in a fish, medaka (Oryzias latipes), to aquatic contaminants

Abstract

Behavioral tests using a fish, medaka (Oryzias latipes), from which the olfactory organs were resected confirmed that fish avoid aquatic contaminants such as surfactants and pesticides mainly by olfaction. Control medaka (non-resected) exhibited significant avoidance to 10, 20 and 30 μg liter−1 of LAS (sodium linear laurylbenzene sulfonate), 90 and 100 μg liter−1 of fenitrothion (dimethyl 4-nitro-m-toryl phosphorothionate), and 500 μg liter−1 of POE-ether (polyoxyethylene lauryl ether). By contrast, medaka with bilateral nose resections (BNRM) exhibited no avoidance to 10–50 μg liter−1 of LAS, 90 and 100 μg liter−1 of fenitrothion, and 500 μg liter−1 of POE-ether. Although medaka with unilateral nose resection (UNRM) avoided some concentrations of these toxicants, the UNRM exhibited no avoidance to 10 and 40 μg liter−1 of LAS and 90 μg liter−1 of fenitrothion. That is, the avoidance response of the UNRM was less distinct than that of the controls. This difference may have been caused by the deterioration of detecting ability and the paralyzation or adaptation of olfaction.