Modeling the contribution of toxicokinetic and toxicodynamic processes to the recovery of Gammarus pulex populations after exposure to pesticides

Abstract

Because aquatic macroinvertebrates may be exposed regularly to pesticides in edge-of-the-field water bodies, an accurate assessment of potential adverse effects and subsequent population recovery is essential. Standard effect risk assessment tools are not able to fully address the complexities arising from multiple exposure patterns, nor can they properly address the population recovery process. In the present study, we developed an individual-based model of the freshwater amphipod Gammarus pulex to evaluate the consequences of exposure to 4 compounds with different modes of action on individual survival and population recovery. Effects on survival were calculated using concentration-effect relationships and the threshold damage model (TDM), which accounts for detailed processes of toxicokinetics and toxicodynamics. Delayed effects as calculated by the TDM had a significant impact on individual survival and population recovery. We also evaluated the standard assessment of effects after short-term exposures using the 96-h concentration-effect model and the TDM, which was conservative for very short-term exposure. An integration of a TKTD submodel with a population model can be used to explore the ecological relevance of ecotoxicity endpoints in different exposure environments.

Development and application of the adverse outcome pathway framework for understanding and predicting chronic toxicity: I. Challenges and research needs in ecotoxicology

“…Recently, a general unified threshold model for survival (GUTS) has been developed, which incorporates a large range of existing TKTD-and DEB-based models for survival as special cases , thus providing even greater flexibility in choosing specific model parameters. To further scale to population, one can use individual-based models (IBMs), ordinary differential equation and matrix population models (Miller and Ankley, 2004;Munns et al, 2008;Kramer et al, 2011), alone or in combination with TKTD or DEB models (Martin et al, 2013;Galic et al, 2014;Jager et al, 2014). Recently, several situation-specific environmental scenarios based on different community composition parameters relevant for an overall population survival (e.g.…”

“…Toxicokinetic-toxicodynamic (TKTD) models provide explicit quantitative links between exposure and effects (Watanabe et al, 2009;Li et al, 2011a;Ashauer and Brown, 2013). Moreover, TKTD models can be applied for modeling sublethal effects and have also proven particularly useful for estimating consequences of fluctuating exposures, as they allow taking into account organism recovery rates Galic et al, 2014). Further, dynamic energy budget (DEB) models provide the means to infer the effects of toxicants that interfere with energy fluxes in the organisms (Sousa et al, 2010).…”

Gammarids as Reference Species for Freshwater Monitoring

“…Such population models are currently increasingly used in predictive approaches (Galic et al, 2010;Kramer et al, 2011), but their use in the diagnostic framework remains limited. Indeed, stage-or size-structured population dynamic models, following either matrix or differential equations formalism (Baird et al, 2007a;Kupisch et al, 2012;Coulaud et al, 2014) as well as individual-based models (Galic et al, 2014) have been proposed in these species. Indeed, stage-or size-structured population dynamic models, following either matrix or differential equations formalism (Baird et al, 2007a;Kupisch et al, 2012;Coulaud et al, 2014) as well as individual-based models (Galic et al, 2014) have been proposed in these species.…”

New approaches to the ecological risk assessment of multiple stressors

“…Whereas toxicokinetic-toxicodynamic models may be used to assess the effects of chemicals in individuals, individual-based, mechanistic and system models can be used to predict effects at the population level. These models can also be linked so that the effect of a chemical can be described from the receptor all the way through to the ecosystem level ( Van den Brink et al 2013;Galic et al 2014;De Laender et al 2015). This is of importance because stressors might affect aquatic ecosystems at different levels of biological organisation.…”