Full life-cycle toxicity assessment using rotifer resting egg production: implications for ecological risk assessment.
The majority of standardized toxicity tests incorporate only a fraction of the test organism's life-cycle. However, in natural ecosystems, organisms may be exposed at various times during their life-cycle or throughout their life-cycle. Thus, ecotoxicological data from standardized toxicity tests is of limited ecological relevance. Existing standardized toxicity tests using the freshwater rotifer Brachionus calyciflorus utilize 24-h survival or 48-h asexual reproduction as endpoints, despite evidence that sexual reproduction is more sensitive. A 96-h B. calyciflorus resting egg toxicity test was developed and used to estimate the toxicity of pentachlorophenol (PCP) and copper. Results were compared to a variety of acute and sublethal endpoints for both toxicants. The B. calyciflorus 96-h resting egg production NOEC for PCP of 10 micrograms/l was 20 times lower than the 48-h asexual reproduction no observed effect concentration (NOEC) and 120 times lower than the 24-h acute lethal concentration 50%. The 96-h resting egg production NOEC for copper of 2.8 micrograms/l was 7 times lower than the 48-h asexual reproduction NOEC and nine times lower than the 24-h acute LC50. Resting egg production was a more sensitive indicator of toxicity than several other sublethal endpoints as well. These results indicate that partial life-cycle toxicity tests are not sufficiently sensitive to detect ecologically relevant adverse effects.
Preston
B L
BL
Carolina Environmental Program, Campus Box 1105, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599-1105, USA. bpreston@email.unc.edu
Snell
T W
TW
D000818:Animals; D002733:Chlorophenols / Q000633:toxicity; D003300:Copper / Q000633:toxicity; D004305:Dose-Response Relationship, Drug; D004463:Ecology; D004531:Eggs; D005260:Female; D012100:Reproduction, Asexual / Q000187:drug effects*; D018570:Risk Assessment; D012403:Rotifera / Q000502:physiology*; D012680:Sensitivity and Specificity; D016019:Survival Analysis; D013997:Time Factors; D018675:Toxicity Tests
D002733:Chlorophenols; D003300:Copper