IP07 Population-Level Ecological Risk Assessment
B113 & B114
8:00 AM - 12:00 PM, Wednesday
(IP051) Selecting relevant endpoints for ecotoxicity testing - what's missing?
Forbes, V1, Calow, P2, Sibly, R3, 1 Roskilde University, Roskilde, Denmark2 University of Sheffield, Sheffield, UK3 University of Reading, Reading, UK
ABSTRACT- Both the species used for ecotoxicity testing and the endpoints that we measure in them are often selected on the basis of their toxicological sensitivity to industrial and agricultural chemicals. Many studies have shown that the most toxicologically sensitive life-cycle traits do not necessarily make the most important contribution to a toxicant′s effects at the population level. This is because life-cycle traits vary in their demographic importance as a function of both life-cycle type and due to biotic and abiotic influences on the values of the suite of life-cycle traits that contributes to population growth rate. We have previously shown that effects of toxicants on population growth rate are rarely greater than effects on the most sensitive life-cycle trait, but that it is difficult to identify the most sensitive traits a priori. Likewise we have shown that the same effect on a life-cycle trait (e.g., juvenile survival) can have vastly different consequences for population growth rate depending on life-cycle type. In the present paper we present new evidence suggesting that there appears to be a negative relationship between toxicological sensitivity of life-cycle traits and their demographic importance (i.e., elasticity). Whereas juvenile survival has a very high elasticity, it is relatively insensitive to chemical impact compared to fecundity, which has a low elasticity but is often the most toxicologically sensitive trait. Though the analysis is preliminary, the results, if borne out by a more extensive data set, have important implications for the selection of relevant endpoints for ecotoxicity testing in general and for the focus on endocrine disrupting effects on reproduction in particular.
Key words: demographic, population growth rate, elasticity, life-cycle trait