Chronic toxicity of lead to three freshwater invertebrates--Brachionus calyciflorus, Chironomus tentans, and Lymnaea stagnalis.
Chronic lead (Pb) toxicity tests with Brachionus calyciflorus, Chironomus tentans, and Lymnaea stagnalis were performed in artificial freshwaters. The no-observable-effect concentration (NOEC), lowest-observable-effect concentration (LOEC), and calculated 20% effect concentration (EC20) for the rotifer B. calyciflorus were 194, 284, and 125 microg dissolved Pb/L, respectively. The midge C. tentans was less sensitive, with NOEC and LOEC of 109 and 497 microg dissolved Pb/L, respectively, and the snail L. stagnalis exhibited extreme sensitivity, evident by NOEC, LOEC, and EC20 of 12, 16, and < 4 microg dissolved Pb/L, respectively. Our findings are presented in the context of other reports on chronic Pb toxicity in freshwater organisms. The L. stagnalis results are in agreement with a previous report on pulmonate snails and should be viewed in the context of current U.S. Environmental Protection Agency (U.S. EPA) hardness adjusted water quality criteria of 8 microg Pb/L. The present findings and earlier reports indicate that freshwater pulmonate snails may not be protected by current regulatory standards. Measurements of whole-snail Na+ and Ca2+ concentrations following chronic Pb exposure revealed that Na+ homeostasis is disturbed by Pb exposure in juvenile snails in a complicated pattern, suggesting two physiological modes of action depending on the Pb exposure concentration. Substantially reduced growth in the snails that exhibit very high Ca2+ requirements may be related to reduced Ca2+ uptake and thereby reduced shell formation.
Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Miami, Florida 33149-1098, USA. mgrosell@rsmas.miami.edu
Martin
M
Grosell
Robert M
RM
Gerdes
Kevin V
KV
Brix
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002683:Chironomidae / Q000187:drug effects*; D005618:Fresh Water; D007854:Lead / Q000032:analysis / Q000633:toxicity*; D008195:Lymnaea / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D019055:No-Observed-Adverse-Effect Level; D012403:Rotifera / Q000187:drug effects*; D012964:Sodium / Q000378:metabolism; D036401:Toxicity Tests, Chronic; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity*
D014874:Water Pollutants, Chemical; D007854:Lead; D012964:Sodium; D002118:Calcium