Acute toxicities of Cd2+, Cr+6 Hg2+, Ni2+ and Zn2+ to estuarine macrofauna.

Static acute toxicity bioassays were conducted at 20 degrees C and 20 o/33 salinity with CdCl2-2 1/2 H20, K2CrO4, HgCl2, NiCl2-6H2O, and ZnCl2 using adults of starfish, Asterias forbesi; sandworm, Nereis virens; hermit crab, Pagurus longicarpus; softshell clam, Mya arenaria; mudsnail, Nassarius obsoletus; and mummichog, Fundulus heteroclitus, a fish. Concentrations (mg/L metal) fatal to 50% of the organisms in 168 hr ranged from 0.004 (clam) to 0.8 (mummichog) for mercury; 0.7 (clam, worm, crab and starfish) to 40.0 (mummichog) for cadimium; 0.2 (crab) to 52.0 (mummichog) for zinc; 0.7 (sandworm) to 44.0 (mummichog) for hexavalent chromium; and 13.0 (starfish) to 150.0 (mummichog) for nickel. Biocidal action was restricted to a relatively narrow range for all species-metals combinations tested: i.e., mean LC-75/LC-25 rations for individual metals at 168 hr ranged between 2.82 (Zn) and 6.02 (Cd); for individual species this ratio extended from 2.76 (fish) to 4.46 (clam). It appears that acute toxicity evaluation of potentially hazardous metals in saline environments requires utilization of at least several representative species from divergent taxonomic and ecological niches.