The effects of pollutants on the behavior of aquatic organisms are being investigated for the purpose of developing behavioral tests applicable to routine toxicological assays. Although behavioral responses are known to be valuable in detecting the biological effects of certain types of pollutants, behavior has rarely been used in routine assays because of the difficulties in making observations and in quantifying behavioral change. We have reduced these problems appreciably through the use of a closed-circuit television system and the quantification of the behavioral record by computer. The behavioral analysis system used is an on-line interactive system capable of analyzing linear and angular parameters of motion for groups of organisms recorded simultaneously. It may be adapted to study material ranging in size from bacteria to fishes.

The findings are presented on the effects of copper and cadmium on selected behaviors of Stage II and III nauplii of the barnacle Balanus improvisus. Both metals alter nondirected (spontaneous) swimming activity in a dose-related biphasic manner, with hyperactivity usually occurring initially, followed by suppressed activity. Copper also alters phototaxis in these nauplii, thus reducing the percentage of individuals displaying positive phototaxis and, at higher concentrations (72 and 138 ppb), causing a shift to negative phototaxis in some individuals. The sensitivity of these behavioral responses is compared with two developmental parameters monitored during the same assay.

Behavioral tests may provide important information for hazard evaluation. Each behavioral alteration observed here may have adverse ecological implications. In addition, tests of nondirected activity and directed responses of aquatic organisms may also be valuable as routine screening tools to identify chemicals toxic to neural or motor systems.