Spills of toxic materials into bodies of water receiving industrial waste discharges can be prevented only if frequent or continuous assessments of wastewater quality can be made. Currently available methods can automatically measure individual physical or chemical waste components, but cannot assess toxicity caused by the interaction of components or the presence of an unsuspected material. Aquatic organisms, on the other hand, respond to their total environment and in this way integrate the effects of all the various chemical and physical waste parameters. The objectives of this study were to evaluate the possibility of using the continuously and automatically recorded physiological and/or behavioral responses of aquatic organisms to monitor the toxicity of industrial waste effluents. The requirements for this type of biological monitoring system and the suitability of various types of organismal responses for use in this manner were reviewed. This was followed by an evaluation of a method which used the computer-monitored ventilatory patterns of 12 bluegills (Lepomis macrochirus Rafinesque) to monitor the toxicity of an industrial waste effluent as it flowed into a river. No known toxic spills occurred in the effluent during any experiment, but a short-term exposure to acetone added to the effluent waste caused responses from the fish at concentrations which peaked near the 96 hour LC50 level. Some responses were also noted when no known toxicant was present; these are related to environmental disturbances and system design problems. Recommendations are made for the design of future biological monitoring units similar to the one tested, and the economic costs of using one of these new systems are discussed. / Ph. D.