Continuous Negotiation in Climate Adaptation: The Challenge of Co-Evolution for the Capability Approach to Justice

The capability approach is increasingly presented as a promising approach to address questions of justice in local climate adaptation. In an attempt to integrate environmental protections into the capability approach, Breena Holland developed the meta-capability Sustainable Ecological Capacity to establish substantive ecological limits. This article, however, empirically demonstrates that defining ecosystem thresholds in co-evolving systems is subject to conflict and continuous negotiation. Taking the Haringvliet dam in the Dutch South-West Delta as an illustrative case, this paper shows how people uphold different views about the Haringvliet’s most desirable ecosystem state. Future shifts in the socio-ecological system, such as decreased fresh water availability and sea-level rise, are expected to uproot today’s compromise about chloride levels in the Haringvliet. This suggests that anticipatory water management should not only address climate impacts, but also prepare for re-negotiations of established ecological thresholds. The associated politics of climate adaptation deals with questions about which functions to protect, at what costs and for whom. Hence, it is critical to integrate procedural justice and attention to political inequalities in capabilities-based adaptation justice frameworks.

Use of the Species Sensitivity Distribution Approach to Derive Ecological Threshold of Toxicological Concern (eco-TTC) for Pesticides

The species sensitivity distribution (SSD) calculates the hazardous concentration at which 5% of species (HC5) will be potentially affected. For many compounds, HC5 values are unavailable impeding the derivation of SSD curves. Through a detailed bibliographic survey, we selected HC5 values (from acute toxicity tests) for freshwater aquatic species and 129 pesticides. The statistical distribution and variability of the HC5 values within the chemical classes were evaluated. Insecticides are the most toxic compounds in the aquatic communities (HC5 = 1.4x10−03 µmol L−1), followed by herbicides (HC5 = 3.3 x10−2 µmol L−1) and fungicides (HC5 = 7.8 µmol L−1). Subsequently, the specificity of the mode of action (MoA) of pesticides on freshwater aquatic communities was investigated by calculating the ratio between the estimated baseline toxicity for aquatic communities and the HC5 experimental values gathered from the literature. Moreover, we proposed and validated a scheme to derive the ecological thresholds of toxicological concern (eco-TTC) of pesticides for which data on their effects on aquatic communities are not available. We proposed eco-TTCs for different classes of insecticides, herbicides, and fungicides with a specific MoA, and three eco-TTCs for those chemicals with unavailable MoA. We consider the proposed approach and eco-TTC values useful for risk management purposes.

Ecological Thresholds of Toxicological Concern: A Review

The ecological threshold of toxicological concern (ecoTTC) is analogous to traditional human health-based TTCs but with derivation and application to ecological species. An ecoTTC is computed from the probability distribution of predicted no effect concentrations (PNECs) derived from either chronic or extrapolated acute toxicity data for toxicologically or chemically similar groups of chemicals. There has been increasing interest in using ecoTTCs in screening level environmental risk assessments and a computational platform has been developed for derivation with aquatic species toxicity data (https://envirotoxdatabase.org/). Current research and development areas include assessing mode of action-based chemical groupings, conservatism in estimated PNECs and ecoTTCs compared to existing regulatory values, and the influence of taxa (e.g., algae, invertebrates, and fish) composition in the distribution of PNEC values. The ecoTTC continues to develop as a valuable alternative strategy within the toolbox of traditional and new approach methods for ecological chemical assessment. This brief review article describes the ecoTTC concept and potential applications in ecological risk assessment, provides an overview of the ecoTTC workflow and how the values can be derived, and highlights recent developments and ongoing research. Future applications of ecoTTC concept in different disciplines are discussed along with opportunities for its use.