Mercury and the estuarine marsh clam, Rangia cuneata Gray. I. Toxicity.

Mercury is relatively toxic to Rangia when exposed to initial high concentrations (1 to 6 ppm) followed by low sustained levels (0.013 to 0.432 ppm). Acclimation to low salinity (2 o/ooS) lessens the toxic effect of mercury. Actual concentrations of mercury causing 50% mortality (LC50) in 96 hr are 122 ppb in 2 o/ooS and 58 ppb in 15 o/ooS. Rangia's ability to survive acute mercury exposure (0.87 +/- 0.15 ppm) is enhanced by low level (8.56 +/- 2.54 ppb) contamination followed by a brief period (9 days) in clean sea water.