BEHAVIORAL RESPONSES IN RAINBOW TROUT Oncorhynchus mykiss AS INDICATORS OF SUBLETHAL EXPOSURE TO HEAVY METALS

Heavy metals are common pollutants of aquatic ecosystems and usually are found in mixtures of various combinations. At present the controlling of pollution of aquatic environment by heavy metals is performed basically by use of analytical investigations. However, biological control of effluent toxicity before effluents are discharged into receiving waters is still seldom used. Therefore, the search into suitable, easy available and maintainable test-objects, their rapid, sensitive, and non-specific test-functions which provide information not only about lethal but also about sublethal effects of pollutants is needed. Fishes are considered to be among the best test-objects. Alterations in a number of fish behavioral responses are sensitive indicators of sublethal exposure to heavy metals and other aquatic pollutants. These are no standardized procedures yet. Laboratory tests were conducted on rainbow trout Oncorhynchus mykiss. Behavioral responses, such as: leaving the nest, response to external stimuli and breathing rate in larvae as well as detection-avoidance, locomotor activity, gill ventilation frequency, and coughing rate in juveniles and adults were investigated. Obtained data showed that fish behavioral responses can be successfully applied in solving not only theoretical but also practical problems of aquatic toxicology, such as bioassay testing for hazard assessment of separate heavy metals and their mixtures, in industrial wastewaters as well as in natural inland waters.