Chronic effects of lead exposure on topsmelt fish (Atherinops affinis): Influence of salinity, organism age, and relative sensitivity to other marine species.

The aim of the present study was to determine the influence of salinity and organism age on the chronic toxicity of waterborne lead (Pb) to Atherinops affinis and to compare the relative Pb sensitivity of A. affinis with other marine species. Chronic Pb exposure experiments were conducted in a water flow-through testing system. Survival, standard length, dry weight, and tissue Pb concentration were measured and lethal concentrations (LCs), effect concentrations (ECs), and bioconcentration factors (BCFs) were calculated. In general, increasing salinity and organism age decreased Pb toxicity. The LC50s for larval fish at 14 and 28 ppt salinity were 15.1 and 79.8 μg/L dissolved Pb, respectively; whereas, the LC50 for juvenile fish was 167.6 μg/L dissolved Pb at 28 ppt salinity. Using standard length data, the EC10 values for larval fish were 16.4 and 82.4 μg/L dissolved Pb at 14 and 28 ppt salinity, respectively. The dry weight EC25s for low and high salinity were 15.6 and 61.84 μg/L dissolved Pb, respectively. The BCFs were higher with the lower salinity study (1703) in comparison to the higher salinity study (654). Results of Pb speciation calculation showed higher fraction of Pb in water with lower salinity, explaining the higher observed toxicity of Pb in lower salinity water than higher salinity water. Atherinops affinis is more sensitive to Pb than several other marine species. Evidence of abnormal swimming and skeletal deformities were observed in Pb exposure treatments. Results of the present study are useful for marine biotic ligand modeling and support ecological risk assessment and deriving Pb environmental quality criteria for marine environments. Environ Toxicol Chem 2018;37:2705-2713. © 2018 SETAC.