Abstract

Data from 183 acute toxicity tests with 97 toxicants and nine crayfish taxa were collected from literature sources to assess the degree of relative toxicity by toxicant use and chemical groups to different crayfish taxa. Toxicity (LC₅₀) values were normalized in a step-wise manner for crayfish life-cycle stages ranging from early instar and juvenile to adults; for exposure periods of 24, 36, 48, 72 and 96 h; and for flow-through tests and static test condition. Early instars were about 3X more sensitive than juveniles and, in turn, juveniles were about 4X more sensitive than adult crayfish to toxicants. Higher toxicant concentrations were required to kill crayfish at shorter exposure times. Conversion factors from 24-h, 36-h, 48-h, and 72-h expo­sures to 96-h exposure time were 0.40, 0.53, 0.67, and 0.88, respectively. Static LC₅₀ values were obtained by multiplying flow-through values by 1.85. Frequency distributions of the normalized LC₅₀ values indicated that insecticides were the most toxic use group in the data. Among the insecticides, the organophosphate and organochlorine compounds were about 17X more toxic than carbamates. Orconectes appeared more sensitive to insecticides than Procambarus; however, separate analysis of the carbamate, organophosphate and organochlorine insecticides failed to detect a difference in sensitivity between these two genera. Procambarus spp. (species unidentified) was less sensitive to insecticides than P. acutus acutus, P. clarkii, and O. nais. A relationship between water temperature and toxicity was observed with carbamate insecticides: toxicity increased by a factor of 5.5 per 10°C rise in test water. A flow-diagram is provided for the incorporation of new LC₅₀ values in the data base and normalization of these LC₅₀ values.

Supplemental Documents

• There are no supplementary documents for this article

Cited By

Citations: