Use of endocommensal molluscan ciliated protozoa as indicators of water quality and pollution in Illinois waters

Abstract

Fifteen species of unionid bivalves from seventeen localities in Central Illinois were carefully examined for ciliate protozoan infections. Many ciliates appeared occasionally, but the thigmotrich ciliates Conchophthirus and Heterocinetopsis unionidarum appeared abundantly and consistently. New observations on the morphology of Conchophthirus and their ultimate effect upon speciation within the genus are to be developed further by the junior author. H. unionidarum was found abundantly at one location. Although Conchophthirus and Heterocinetopsis were the only thigmotrichs uncovered in this study, the isolation of Heterocinetopsis suggests that other thigmotrich ciliates may also be found in Illinois. The ciliates Conchophthirus and Heterocinetopsis were tested for their ability to react as very delicate indicators of water quality. This was accomplished by planting infected bivalves in areas of known pollution in the Salt Fork Vermilion River dra.ina.ge system. At intervals after planting, individuals were recovered and carefully examined for the relative abundance of Conchophthirus and Heterocinetopsis. The preliminary results suggest that Heterocinetopsis may be the most critical indicator of biological pollution currently available for Illinois waters.U.S. Department of the InteriorU.S. Geological SurveyOpe