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 oil 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.
Original language | English |
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Pages (from-to) | 1465-1472 |
Journal | Environmental Toxicology and Chemistry |
Volume | 22 |
Issue number | 7 |
DOIs | |
Publication status | Published - 2003 |
Keywords
- earthworm eisenia-foetida
- phenotypic plasticity
- toxicity test
- life-history
- heavy-metals
- reproduction
- fitness
- soil
- growth
- stress