T5 AM Terrestrial Ecotoxicology
Tuesday, 15 November 2005: 8:00 AM - 11:40 AM in 321-323

(JAG-1117-747791) Extrapolation from lab tests to field populations using Dynamic Energy Budgets.

Jager, T¹, Alda Alvarez, O², Kammenga, J², Kooijman, SALM¹, ¹ Vrije Universiteit, Dept. Theoretical Biology, Amsterdam, The Netherlands² Wageningen University, Dept. Nematology, Wageningen, The Netherlands

ABSTRACT- The main objective of ecological risk assessment is to protect field populations or ecosystems. However, most laboratory tests are not suited for an extrapolation to such endpoints. Acute mortality bears little or no relation to population consequences, and growth alone is also not sufficient (for some chemicals, growth is not affected at concentrations that seriously reduce reproduction). The most useful tests are (partial) life-cycle tests, following more endpoints (growth, reproduction and survival) over a longer period of time. Survival and reproduction in time can be used to predict the intrinsic rate of population increase, which is a far more relevant endpoint that any individual endpoint by itself. However, life-cycle data contain much more information about the eco-physiology of the organism and the mode of action of the chemical. To unlock this information, we use the theory of Dynamic Energy Budgets (DEB). The DEB theory aims to quantify individual growth, development and reproduction on the basis of a set of simple rules for metabolic organisation. The effects of toxicants can be understood as a change in energetic parameters, such as an increase in maintenance costs, or the costs for egg production. In this way, effects of toxicants are quantified, explicitly accounting for exposure time (as recommended by the 1996 OECD meeting in Braunsweig). Identifying the energetics-based mode of action is not only interesting from a scientific viewpoint, it is also crucial to extrapolate to population responses under field conditions. Because DEB is based on mechanisms, it is possible to explore the effects of food limitation (an additional stressor, common in the field) or different temperatures, by model simulations. We illustrate the advantages of a DEB-based analysis with data for springtails and terrestrial nematodes.

Key words: extrapolation, dynamic energy budgets, dose-effect modelling, effects assessment