Heliophrya sp., a new protozoan biomonitor of pollution: culture techniques, toxin uptake and elimination, and field studies in an oil-polluted stream

The stalkless suctorian Heliophyra sp., a sessile ciliated protozoan, was used as a pollution biomonitor. The research objectives were to determine: (1) optimal culture conditions and techniques for biotoxicity testing; (2) ability of Helipophrya to incorporate and eliminate a 14C oil component and other organic toxins; (3) suitability of Heliophrya as a biomonitor of oil pollution. Selection of culture conditions for Heliophrya were based on survival over a three week period and ability to divide when fed after three weeks. The LC50 (lethal concentration for 50% of the population) for 96 h was 12.4 ppt salinity. Heliophrya were exposed to 14C toxins for 48 h, then organisms were transferred to nonradioactive water for 96 h. The uptake rate of 14C octachlorostyrene was higher than 14C phenanthrene or 14C diisononyl phthalate. Elimination rates were comparable to other test organisms. Heliophrya and d. pulex were placed at three stations, in a stream which received chronic oil pollution, for periods of 48 h and seven days. A 48 h lab test with dilutions of field water was performed. Water samples were analyzed by gas chromatography and mass spectrometry. Death of Heliophrya at the three polluted stations over 48 h was not significantly greater than at a less polluted tributary; however, all the Daphnia in the polluted stream stations were killed. In the seven day field study, Heliophrya had an estimated LC50 of 1 ppm for the aromatic and 29 ppm for the total hydrocarbons. Compared to other species, Heliophrya is moderately sensitive to oil pollution, and is a good companion biomonitor to the more sensitive Daphnia