Environmental monitoring using physiological telemetry—a case study examining common carp responses to thermal pollution in a coal-fired generating station effluent

the response of common carp (Cyprinus carpio) to fluctuating thermal conditions was studied in the Nanticoke Thermal Generating Station discharge canal on Lake Erie. Locomotory activity of fish in the canal was monitored using electromyogram telemetry of the axial musculature. Carp activity was variable but, in general, they were more active during times of rising and falling temperatures, and were least active during stable periods. The magnitude of water temperature fluctuation was not correlated with activity. Locomotory activity of fish was not generally correlated with absolute water temperature over a wide range of temperatures (∼2 to 18 ◦C) when examined on an hourly basis, but was moderately correlated at a finer temporal resolution (5 min). During a station shutdown, one carp stayed in the canal and experienced a sub-stantial decrease in temperature yet exhibited no significant change in activity. The results of this study suggest that minor temperature changes (∼0.1 ◦C per hour) are sufficient to alter activity, probably through fine scale behavioral thermoregulation. The heightened activity resulting from slight changes in temperature may be energetically costly in environments that change as rapidly as thermal effluents. Physiological telemetry permitted us to study the in situ response of fish to dynamic environmental conditions with more precision than is possible using locational telemetry. We suggest