Ref ID : 1874
James R. Pratt, D. Mochan, and Zhenkang Xu; Rapid toxicity estimation using soil ciliates: Sensitivity and bioavailability. Bull.Environ.Contam.Toxicol. 58:387-393, 1997
Reprint
In File
Notes
Several characteristics of soil ciliates make them ideal toxicity test organisms. Ciliates are ubiquitous in ecosystems and play major roles in decomposition by cropping bacteria. Many ciliates form resistant resting stages, usually cysts that allow the organisms to remain dormant during adverse conditions (e.g., drying) and then to exploit acceptable conditions rapidly. Growth rates can be high (3-4 doublings per day). Although many of the most opportunistic species are poor competitors (Foissner et al. 1991), the ability of these organisms to grow quickly from resting stages can be exploited for toxicological purposes. Opportunistic or pioneer species have been shown to be more sensitive to toxic chemicals than the slower growing species that comprise the remainder of communities (Ruthven and Cairns 1972, Hart and Cairns 1984). Previous studies have shown the utility of ciliates in assessing toxicity. Most of these studies have concentrated on the response of the ciliate Tetrahymena pyriformis to a variety of toxicants (e.g., Roberts and Berk 1990), and T. pyriformis model has been used in developing quantitative structure-activity relationships (e.g., Schultz et al. 1994). Ciliate behavior has been used to assess the effects of metals (Berk et al. 1985). Recently, a growth test using the ciliate Colpidium campylum has been developed and tested in several laboratories (Dive et al. 1990). An essential feature of effective assessment tools in the ability to simulate field exposure (Forbes and Forbes 1994). For many evaluations, laboratory testing requires shipping and holding field samples, reducing environmental realism. Test procedures that minimize culturing enable testing at or near field sites with minimal laboratory facilities. We examined the sensitivity of a C. inflata growth test to different toxic metals and evaluated the effects of test media with differing dissolved organic carbon content to assess bioavailability of the tested toxicants.