SENSITIVITY OF EARLY LIFE STAGES OF FRESHWATER MUSSELS (UNIONIDAE) TO ACUTE AND CHRONIC TOXICITY OF LEAD, CADMIUM, AND ZINC IN WATER

摘要

Toxicity of lead, cadmium, or zinc to early life stages of freshwater mussels (fatmucket, Lampsilis siliquoidea; Neosho mucket, L. rafinesqueana) was evaluated in 48-h exposures with mussel larvae (glochidia), in 96-h exposures with newly transformed (5-d-old) and two-or six-month-old juvenile mussels, or in 28-d exposures with two-or four-month-old mussels in reconstituted soft water. The 24-h median effect concentrations (EC50s) for fatmucket glochidia (>299 μg Pb/L, >227 μg Cd/L, 2,685 μg Zn/L) and 96-h EC50s for two- or six-month-old fatmucket (>426μg Pb/L, 199 μg Cd/L, 1.700 μg Zn/L) were much higher than 96-h EC50s for newly transformed fatmucket (142 and 298 μg Pb/L, 16 μg Cd/L, 151 and 175 μg Zn/L) and Neosho mucket (188 μg Pb/L, 20 μg Cd/L, 145 μg Zn/L). Chronic values for fatmucket were 10 ug Pb/L, 6.0 ug Cd/L, and 63 and 68 μg Zn/L. When mussel data from the present study and the literature were included in updated databases for deriving U.S. Environmental Protection Agency water quality criteria, mussel genus mean acute values were in the lower perccntiles of the sensitivity distribution of all freshwater species for Pb (the 26th percentile), Cd (the 15th to 29th percentile), or Zn (the 12th to 21st percentile). The mussel (Lampsilis) genus mean chronic value was the lowest value ever reported for Pb (the 9th percentile) but was near the middle of the sensitivity distribution for Cd (the 61st percentile) or Zn (the 44th percentile). These results indicate that mussels were relatively sensitive to the acute toxicity of these three metals and to the chronic toxicity of Pb, but were moderately sensitive to the chronic toxicity of Cd or Zn compared to other freshwater species.