title: Quantifying copper and cadmium impacts on intrinsic rate of population increase in the terrestrial oligochaete Lumbricus rubellus.
abstract: Demographic methods can translate toxicant effects on individuals into consequences for populations. To date few such studies have been conducted with longer-lived invertebrates. This is because full life-cycle experiments are difficult with such species. Here we report the effects of copper and cadmium on the key demographic parameter intrinsic rate of population increase (r) in a long-lived invertebrate (an earthworm). The approach used to derive r was based on robust measurement of effects on life-cycle traits in three specifically designed toxicity tests and integration of this data within a demographic model. The three laboratory tests used to generate values for specific life-cycle parameters under copper and cadmium exposure were suited to the task. Significant effects on a range of separate adult and juvenile life-cycle parameters were seen. Integration of parameter values within the demographic equation indicated that for copper, r was reduced only at a concentration that also caused adult mortality. For cadmium, a more graded exposure-dependent effect on fitness was seen, with r reduced at sublethal concentrations. The concentration response patterns for r found for the two metals suggest significantly different consequences for earthworm populations exposed to sublethal levels of copper and cadmium.
authors.affiliation: Centre for Ecology and Hydrology, Monks Wood, Abbotts Ripton, Huntingdon, Cambridgeshire, PE28 2LS, United Kingdom. dasp@ceh.ac.uk
authors.forename: David J
authors.initials: DJ
authors.lastname: Spurgeon
authors.forename: Claus
authors.initials: C
authors.lastname: Svendsen
authors.forename: Jason M
authors.initials: JM
authors.lastname: Weeks
authors.forename: Peter K
authors.initials: PK
authors.lastname: Hankard
authors.forename: Hege E
authors.initials: HE
authors.lastname: Stubberud
authors.forename: Jan E
authors.initials: JE
authors.lastname: Kammenga
mesh_terms: D000818:Animals; D002105:Cadmium Poisoning / Q000473:pathology / Q000662:veterinary*; D003300:Copper / Q000506:poisoning*; D004781:Environmental Exposure; D004785:Environmental Pollutants / Q000506:poisoning*; D005260:Female; D008297:Male; D008962:Models, Theoretical; D009026:Mortality; D009835:Oligochaeta / Q000502:physiology*; D011157:Population Dynamics; D012098:Reproduction / Q000187:drug effects; D016019:Survival Analysis
chemical_list: D004785:Environmental Pollutants; D003300:Copper