Individual-based modelling of the recovery of Chaoborus crystallinus in aquatic mesocosm pond studies
The recovery time of chemically stressed populations in aquatic outdoor mesocosms studies is very important for the risk assessment of pesticides. Insects like the phantom midge Chaoborus crystallinus can recover from inside the polluted ponds (autochthonous recovery), and by immigration of adults from uncontaminated ponds (allochthonous recovery). In both mechanisms, the recovery time depends on the strength of toxic effects, population density and spatial vicinity of other non-affected populations. Smaller populations have a higher extinction probability than larger ones, and isolated populations are more sensitive due to the lack of immigration from outside. The dipteran Chaoborus crystallinus, a pelagic invertebrate predator, is well known for its sensitivity to insecticide toxicity, especially the first instars.
Chaoborus crystallinus larvae
Modelled life history of Chaoborus
To analyse the recovery time and extinction probability after pesticide application, an individual-based population model for Chaoborus crystallinus has been developed to include the complete life. Density-dependent processes like cannibalism and emigration are important factors for the regulation of population density. The model was validated with experimental data from aquatic outdoor mesocosms, and was used to compare the long and short-term recovery behaviour of isolated and connected populations following exposure to pesticides. In the newest version, the Chaoborus population model was coupled with the General Unified Threshold model for Survival (GUTS, Jager et al. 2011) explicitly simulating toxicokinetics and toxicodynamics (TKTD).
Publications
Presentations
Strauss T, Ratte HT (2003): Individuenbasierte Modellierung in der Ökotoxikologie am Beispiel von Chaoborus crystallinus. Vortrag SETAC-GLB-Jahrestagung, Heidelberg, 21.- 23. September 2003.