A chronic toxicity test for the tropical marine snail Nassarius dorsatus to assess the toxicity of copper, aluminium, gallium, and molybdenum

Chronic toxicity test methods for assessing the toxicity of contaminants to tropical marine organisms are generally lacking. A 96-h chronic growth rate toxicity test was developed for the larval stage of the tropical dogwhelk, Nassarius dorsatus. Growth rates of N. dorsatus larvae were assessed following exposures to copper (Cu), aluminium (Al), gallium (Ga), and molybdenum (Mo). Exposure to Cu at 28 °C validated the sensitivity of the test method, with 10% (EC10) and 50% (EC50) effect concentrations of 4.2 μg/L and 7.3 μg/L Cu, respectively. The EC10 and EC50 values for Al (<0.45-μm filtered fraction) at 28 °C were 115 μg/L and 185 μg/L, respectively. The toxicity of Cu and Al was also assessed at 24 °C and 31 °C, representing average year-round water temperatures for subtropical and tropical Australian coastal environments. At 24 °C, the growth rate of control larvae was reduced by 52% compared with the growth rate at 28 °C and there was an increase in sensitivity to Cu (EC50 = 4.7 μg/L) but a similar sensitivity to Al (EC50 = 180 μg/L). At 31 °C the control growth rate increased by 35% from that measured at 28 °C and there was reduced sensitivity to both Cu and Al (EC50s = 8.5 μg/L and 642 μg/L, respectively). There was minimal toxicity resulting from Ga (EC50 = 4560 μg/L) and Mo (no effect at ≤7000 μg/L Mo).