Differences in acute toxicity test results of three reference toxicants onDaphniaat two temperatures

摘要

AbstractTen 48‐h static acute toxicity tests were conducted withDaphnia magnaStraus andDaphnia pulexLeydig with each of the three reference toxicants — sodium dodecyl sulfate (SDS), sodium pentachlorophenate (NaPCP), and cadmium (Cd) (as CdCl2) — at 20 and 26°C to investigate the effect of temperature on test results at the temperature extremes usually encountered during field studies. The mean 48‐h LC50 value for SDS withDaphnia pulexat 26°C was lower (10.2 mg/L) than at 20°C (12.6 mg/L), but the difference was not significant (α = 0.05). ForDaphnia magnathe mean LC50 was significantly (α = 0.05) lower at 26°C (10.8 mg/L) than at 20°C (13.5 mg/L). Sensitivity of either species to NaPCP was not significantly different (α = 0.05) at the two temperatures. The data show a fourfold increase in sensitivity to Cd at the higher temperature withDaphnia magna(mean LC50 = 0.038 mg/L at 20°C and 0.009 mg/L at 26°C) and a sevenfold increase withDaphnia pulex(mean LC50 = 0.042 mg/L at 20°C and 0.006 mg/L at 26°C). These data indicate that toxicity tests conducted at 20 and 26°C may give significantly different results withDaphnia.Because test precision, control survival, and the likelihood of obtaining valid tests are better at 20°C, that temperature is recommended for acute toxic