MORTALITY AND LC50 VALUES FOR SEVERAL STAGES OF THE MARINE COPEPOD TIGRIOPUS-BREVICORNIS (MULLER) EXPOSED TO THE METALS ARSENIC AND CADMIUMAND THE PESTICIDES ATRAZINE, CARBOFURAN, DICHLORVOS, AND MALATHION

The toxicity of three insecticides (carbofuran, dichlorvos, malathion) , an herbicide (atrazine), and two metals (arsenic and cadmium) to ovi gerous females, copepodids, and nauplii of Tigriopus brevicornis was d etermined by 96-h semistatic (or static-renewal) bioassays, Freshly pr epared aqueous stock solutions of these pesticides and metals were dil uted to appropriate concentrations. Mortalities were recorded and test solutions were changed completely each day up to 96 h, The rate of mo rtality was analyzed for linear regressions, and LC50 values were dete rmined by probit analysis, LC50 values for ovigerous T, brevicornis fe males were 153.2 mu g liter(-1) for atrazine, 59.9 mu g liter(-1) for carbofuran, 47.9 mu g liter(-1) for cadmium, 27.5 mu g liter(-1) for a rsenic, 24.3 mu g liter(-1) for malathion, and 4.6 mu g liter(-1) for dichlorvos, Comparison of the overall toxicities of these pesticides a nd metals indicated that dichlorvos was the most toxic substance to T, brevicornis, followed by malathion, arsenic, cadmium, carbofuran, and atrazine. Available LC,, data indicate that marine copepods are more sensitive to pollutants than Daphnia magna, Acartia tonsa, and Tisbe b attagliai, or as sensitive as the mysid Mysidopsis bahia. (C) 1998 Aca demic Press.