Earthworm responses to Cd and Cu under fluctuating environmental conditions: a comparison with results from laboratory exposures.
Laboratory toxicity tests are usually conducted under stable ambient conditions, while exposures in ecosystems occur in a fluctuating climate. To assess how climate influences the toxicity of Cu and Cd for the earthworm Lumbricus rubellus, this study compared effects for life-cycle parameters (survival, reproduction), cellular status (lysosomal membrane stability), gene expression (transcript of the metal binding protein metallothionein-2) and tissue metal concentration measured under outdoor conditions, with the same responses under constant conditions as measured by Spurgeon et al. [Spurgeon, D.J., Svendsen, C., Weeks, J.M., Hankard, P.K., Stubberud, H.E., Kammenga, J.E., 2003. Quantifying copper and cadmium impacts on intrinsic rate of population increase in the terrestrial oligochaete Lumbricus rubellus. Environmental Toxicology and Chemistry 22, 1465-1472]. Both metals were found to significantly influence earthworm reproduction, compromise lysosomal membrane stability and induce MT-2 gene expression in the outdoor system. Comparison with physiological and life-cycle responses in the laboratory indicated similar response patterns and effect concentrations for Cu. For Cd, lysosomal membrane stability and MT-2 expression showed comparable responses in both exposures. Juvenile production rate, however, gave different dose response relationships, with the EC-(50) in the outdoor test approximately half that in the laboratory test. A difference in Cd accumulation was also seen. Overall, however, the comparison indicated only a marginal effect of environmental fluctuations typical for northern temperate Europe on earthworm sensitivity to the two metals.
Spurgeon
David J
DJ
Centre for Ecology and Hydrology, Monks Wood, Abbots Ripton, Huntingdon, Cambridgeshire, PE28 2LS, UK. dasp@ceh.ac.uk
Svendsen
Claus
C
Lister
Lindsay J
LJ
Hankard
Peter K
PK
Kille
Peter
P
D000818:Animals; D002104:Cadmium / Q000633:toxicity*; D002980:Climate; D003300:Copper / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression / Q000187:drug effects; D007928:Lethal Dose 50; D008247:Lysosomes / Q000378:metabolism; D008668:Metallothionein / Q000235:genetics; D009835:Oligochaeta / Q000187:drug effects* / Q000378:metabolism
D002104:Cadmium; D003300:Copper; D008668:Metallothionein