Nauplii and adults of Robertsonia propinqua , a marine sediment‐dwelling copepod, were used in 96‐h static range‐finder toxicity tests to assess the lethal concentration at which 50% of test organisms are killed (LC 50 ) by atrazine (a herbicide) and zinc sulfate. Atrazine and zinc sulfate were used at concentrations near LC 50 values published for crustaceans. LC 50 values for R. propinqua nauplii were 1.5 mg/litre for atrazi...

The susceptibility (48‐h LC 50 values) of aquatic life stages of Xanthocnemis zealandica McLachlan to azinphos‐methyi and carbaryi was investigated. The LC50 values of azinphos‐methyi did not correlate with instar. The most susceptible stage was instar 7 (LC 50 value: 26.6 ppb), and the least susceptible were instars 2 (LC50 value: 50.2 ppb) and 13 (LC 50 value: 45.1 ppb). In contrast, LC 50 values for carbaryi were positively...