Disturbance interactions: the combined effects of toxicants and environmental stochasticity on collembolans
The overall aim of the project is to estimate collembolan population response to elevated metal (and possibly pesticide) concentrations in soil and environmental stochasticity (fluctuating temperature) of different magnitude and frequency. The species to be used represent two contrasting reproduction strategies: parthenogenesis (Folsomia candida) and sexual reproduction (Sinella curviseta), allowing a comparison of effects on otherwise similar species.
Basic population parameters and extinction probabilities will be calculated to give better insight into collembolan population dynamics in such conditions. Obtained data will be used by Soil-3 (in collaboration with Soil-2) to construct, tune and validate mechanistic effect models for collembolan populations.
Soil-2 and Soil-3 will provide a close interaction between experimental work and modelling: while Soil- 2 is more concentrated on empirical studies, the aim of Soil-3 is to deliver final and reliable versions of mechanistic effect models (both matrix and IBMs) for collembolan population under elevated metal concentrations and environmental stochasticity. Conceptual links between Soil-2 and Soil-3 are shown in Figure 1.
Main questions to be answered by Soil-2 are:
- What is the collembolan population response to toxicants depending on different environmental fluctuations?
- How can we reliably extrapolate experimentally-obtained responses to natural populations?
- Is it possible to integrate obtained results into Ecological Risk Assessment guidelines and protocols and to what extent?
Different experimental set-ups will be used to study collembolan population dynamics. Experiment planned for now are competition experiment (COMPEX), OECD-based short-term experiment (STEX) and long-term experiment (LTEX). Different side-ideas are still to be considered for experimental and field work. (For example setting mesocosm experiments in cooperation with CREAM associated partners, or comparing field data on populations under toxic stress from different localities).
Matrix modelling approach will be dominantly used for obtained data sets.
Published work on collembolan under combined stress will be carefully reviewed, as well as published papers on the possible use of different modelling techniques in chemical risk assessment.
The results should provide a better understanding of population toxic effects in stochastic environmental conditions. Models which will be developed based on these results may be used as a tool for the extrapolation of toxic effects from individual to population level, and hence provide a reliable tool for ecological risk assessment of chemicals.
Last Update: 15 September 2010