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Toxicity testing with artificial streams: Effects of differences in current velocity
Author(s) -
Lowell Richard B.,
Culp Joseph M.,
Wrona Frederick J.
Publication year - 1995
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620140713
Subject(s) - mayfly , toxicant , toxicity , ec50 , toxicology , current (fluid) , streams , chemistry , zoology , biology , ecology , nymph , computer network , biochemistry , computer science , engineering , organic chemistry , electrical engineering , in vitro
When designing toxicity tests with lotic organisms, the role of current velocity is a key consideration when evaluating the test organism's response. We conducted a series of short‐term toxicity experiments with the mayfly Baetis tricaudatus Dodds to determine the effect of current velocity on mayfly response to the reference toxicant sodium chloride. The tests were run at three substratum‐level velocities: low (0 cm/s), medium (6 cm/s, typical of estimated intrasubstratum velocities in the field), and high (12 cm/s). The end points measured for the mayflies were immobilization and number of molts. The animals showed signs of stress, and the EC50 was lower in the 0 cm/s treatment, probably due to insufficient delivery of oxygen to the gills. This did not, however, lead to much change in sensitivity (measured as lowest‐observed‐effect concentration; LOEC) to the reference toxicant. Furthermore, neither EC50 nor LOEC differed between 6 and 12 cm/s. This suggests a threshold between 0 and 6 cm/s above which the effect of current velocity was no longer measurable. These results provide initial support for the recommendation that short‐term toxicity tests using lotic organisms should ensure that the animals are exposed to at least some flow. Long‐term tests, and those with different toxicants, may require further fine‐tuning of current velocity.