Predicting impacts of chemicals from organisms to ecosystem service delivery: A case study of endocrine disruptor effects on trout

We demonstrate how mechanistic modeling can be used to predict whether and how biological responses to chemicals at (sub)organismal levels in model species (i.e., what we typically measure) translate into impacts on ecosystem service delivery (i.e., what we care about). We consider a hypothetical case study of two species of trout, brown trout (Salmo trutta; BT) and greenback cutthroat trout (Oncorhynchus clarkii stomias; GCT). These hypothetical populations live in a high-altitude river system and are exposed to human-derived estrogen (17α‑ethinyl estradiol, EE2), which is the bioactive estrogen in many contraceptives. We use the individual based model in STREAM to explore how seasonally varying concentrations of EE2 could influence male spawning and sperm quality. Resulting impacts on trout recruitment and the consequences of such for anglers and for the continued viability of populations of GCT (the state fish of Colorado) are explored. in STREAM incorporates seasonally varying river flow and temperature, fishing pressure, the influence of EE2 on species-specific demography, and inter-specific competition. The model facilitates quantitative exploration of the relative importance of endocrine disruption and inter-species competition on trout population dynamics. Simulations predicted constant EE2 loading to have more impacts on GCT than BT. However, increasing removal of BT by anglers can enhance the persistence of GCT and offset some of the negative effects of EE2. We demonstrate how models that quantitatively link impacts of chemicals and other stressors on individual survival, growth, and reproduction to consequences for populations and ecosystem service delivery, can be coupled with ecosystem service valuation. The approach facilitates interpretation of toxicity data in an ecological context and gives beneficiaries of ecosystem services amore explicit role in management decisions. Although challenges remain, this type of approach may be particularly helpful for site-specific risk assessments and those in which trade offs and synergies among ecosystem services need to be considered

Validation of the OECD reproduction test guideline with the New Zealand mudsnail Potamopyrgus antipodarum using trenbolone and prochloraz

The Organisation for Economic Cooperation and Development (OECD) provides several standard test methods for the environmental hazard assessment of chemicals, mainly based on primary producers, arthropods, and fish. In April 2016, two new test guidelines with two mollusc species representing different reproductive strategies were approved by OECD member countries. One test guideline describes a 28-day reproduction test with the parthenogenetic New Zealand mudsnail Potamopyrgus antipodarum. The main endpoint of the test is reproduction, reflected by the embryo number in the brood pouch per female. The development of a new OECD test guideline involves several phases including inter-laboratory validation studies to demonstrate the robustness of the proposed test design and the reproducibility of the test results. Therefore, a ring test of the reproduction test with P. antipodarum was conducted including eight laboratories with the test substances trenbolone and prochloraz and results are presented here. Most laboratories could meet test validity criteria, thus demonstrating the robustness of the proposed test protocol. Trenbolone did not have an effect on the reproduction of the snails at the tested concentration range (nominal: 10-1000 ng/L). For prochloraz, laboratories produced similar EC10 and NOEC values, showing the inter-laboratory reproducibility of results. The average EC10 and NOEC values for reproduction (with coefficient of variation) were 26.2 µg/L (61.7%) and 29.7 µg/L (32.9%), respectively. This ring test shows that the mudsnail reproduction test is a well-suited tool for use in the chronic aquatic hazard and risk assessment of chemicals

Compréhension et modélisation des relations entre les caractéristiques biologiques et écologiques et la sensibilité aux contaminants des communautés d'invertébrés benthiques : perspectives pour l'évaluation des effets des substances chimiques

We sought to improve the ecological relevance of the existing effect assessment methods for benthic invertebrate communities. We have thus developed a method, which permits to build test batteries that are representative of the functioning of natural communities. It is based on the statistical analysis of the combinations of 22 biological and ecological traits for 479 western European invertebrate species. We used this method in order to build a test battery that represents the functioning of benthic communities that inhabit fine sediments of lowland rivers and lakes in Western Europe. This battery gathers five species: Chironomus riparius, Valvata piscinalis, Branchiura sowerbyi, Lumbriculus variegatus and Sericostoma personatum. We have then sought to characterize the biological response to zinc of lab populations for C. riparius, V. piscinalis and B. sowerbyi. For these species, we developed handling and breeding methods and described their life cycle at the lab in clean sediments. Then, we ran toxicity tests to characterize the effects of zinc on individual survival, growth and reproduction. Test data were first analyzed at the individual level using mechanistic models based on the perturbation of energy budgets by the toxicant. On the basis of both the data from toxicity tests and the effects models, we estimated the effects of zinc at the population level using matrix population models. Finally, we used population level results to derive a no effect concentration for the benthic community. The study of population effects of zinc on C. riparius, V. piscinalis and B. sowerbyi allowed us to estimate (at the lab) a no effect concentration for the benthic community, which is reliable when compared to field results. The validation and the adaptation the methods we used for routine effect assessment of chemicals represents the major prospects of our work.Nous avons cherché à améliorer la pertinence écologique des méthodes existantes d'évaluation des effets des substances chimiques pour les communautés d'invertébrés benthiques. Nous avons tout d'abord mis au point une méthode qui permet de construire des batteries de test représentatives du fonctionnement des communautés naturelles grâce à l'analyse statistique des combinaisons de 22 caractéristiques biologiques et écologiques pour 479 espèces d'invertébrés rencontrées en Europe de l'Ouest. Nous avons utilisé cette méthode afin de construire une batterie de test représentative de la communauté d'invertébrés inféodés aux sédiments de zone aval de cours d'eau et de lacs. Cette batterie est constituée de cinq espèces: Chironomus riparius, Valvata piscinalis, Branchiura sowerbyi, Lumbriculus variegatus et Sericostoma personatum. Nous avons alors caractérisé la réponse biologique au zinc des populations de laboratoire pour C. riparius, V. piscinalis et B. sowerbyi. Pour ce faire, nous avons mis au point des méthodes d'élevage, décrit le cycle de vie en laboratoire en milieu propre et réalisé des tests de toxicité afin de caractériser les effets d'une contamination du sédiment par le zinc sur la survie, la croissance et la reproduction des organismes. Ces effets ont été analysés au niveau individuel grâce à des modèles basés sur la perturbation de la gestion de l'énergie par le toxique. A partir de données individuelles, nous avons estimé les effets attendus au niveau des populations en couplant ces modèles d'effets sur les individus avec des modèles biodémographiques matriciels basés sur l'étude du cycle de vie des organismes. L'étude de la sensibilité au zinc des populations de C. riparius, V. piscinalis et B. sowerbyi nous a permis d'estimer une concentration sans effet du zinc sur les communautés benthiques qui est relativement fiable par rapport aux résultats observés sur le terrain. La validation et l'adaptation des outils proposés en vue d'une utilisation en routine pour l'évaluation des effets des substances chimiques représentent les perspectives majeures de la thèse

Compréhension et modélisation des relations entre les caractéristiques biologiques et écologiques et la sensibilité aux contaminants des communautés d'invertébrés benthiques (perspectives pour l'évaluation des effets des substances chimiques)

Nous avons cherché à améliorer la pertinence écologique des méthodes existantes d'évaluation des effets des substances chimiques pour les communautés d'invertébrés benthiques. Nous avons tout d'abord mis au point une méthode qui permet de construire des batteries de test représentatives du fonctionnement des communautés naturelles grâce à l'analyse statistique des combinaisons de 22 caractéristiques biologiques et écologiques pour 479 espèces d'invertébrés rencontrées en Europe de l'Ouest. Nous avons utilisé cette méthode afin de construire une batterie de test représentative de la communauté d'invertébrés inféodés aux sédiments de zone aval de cours d'eau et de lacs. Cette batterie est constituée de cinq espèces: Chironomus riparius, Valvata piscinalis, Branchiura sowerbyi, Lumbriculus variegatus et Sericostoma personatum. Nous avons alors caractérisé la réponse biologique au zinc des populations de laboratoire pour C. riparius, V. piscinalis et B. sowerbyi. Pour ce faire, nous avons mis au point des méthodes d'élevage, décrit le cycle de vie en laboratoire en milieu propre et réalisé des tests de toxicité afin de caractériser les effets d'une contamination du sédiment par le zinc sur la survie, la croissance et la reproduction des organismes. Ces effets ont été analysés au niveau individuel grâce à des modèles basés sur la perturbation de la gestion de l'énergie par le toxique. A partir de données individuelles, nous avons estimé les effets attendus au niveau des populations en couplant ces modèles d'effets sur les individus avec des modèles biodémographiques matriciels basés sur l'étude du cycle de vie des organismes. L'étude de la sensibilité au zinc des populations de C. riparius, V. piscinalis et B. sowerbyi nous a permis d'estimer une concentration sans effet du zinc sur les communautés benthiques qui est relativement fiable par rapport aux résultats observés sur le terrain. La validation et l'adaptation des outils proposés en vue d'une utilisation en routine pour l'évaluation des effets des substances chimiques représentent les perspectives majeures de la thèseWe sought to improve the ecological relevance of the existing effect assessment methods for benthic invertebrate communities. We have thus developed a method, which permits to build test batteries that are representative of the functioning of natural communities. It is based on the statistical analysis of the combinations of 22 biological and ecological traits for 479 western European invertebrate species. We used this method in order to build a test battery that represents the functioning of benthic communities that inhabit fine sediments of lowland rivers and lakes in Western Europe. This battery gathers five species: Chironomus riparius, Valvata piscinalis, Branchiura sowerbyi, Lumbriculus variegatus and Sericostoma personatum. We have then sought to characterize the biological response to zinc of lab populations for C. riparius, V. piscinalis and B. sowerbyi. For these species, we developed handling and breeding methods and described their life cycle at the lab in clean sediments. Then, we ran toxicity tests to characterize the effects of zinc on individual survival, growth and reproduction. Test data were first analyzed at the individual level using mechanistic models based on the perturbation of energy budgets by the toxicant. On the basis of both the data from toxicity tests and the effects models, we estimated the effects of zinc at the population level using matrix population models. Finally, we used population level results to derive a no effect concentration for the benthic community. The study of population effects of zinc on C. riparius, V. piscinalis and B. sowerbyi allowed us to estimate (at the lab) a no effect concentration for the benthic community, which is reliable when compared to field results. The validation and the adaptation the methods we used for routine effect assessment of chemicals represents the major prospects of our workMETZ-SCD (574632105) / SudocSudocFranceF

How to account for the uncertainty from standard toxicity tests in species sensitivity distributions: An example in non-target plants.

This research proposes new perspectives accounting for the uncertainty on 50% effective rates (ER50) as interval input for species sensitivity distribution (SSD) analyses and evaluating how to include this uncertainty may influence the 5% Hazard Rate (HR5) estimation. We explored various endpoints (survival, emergence, shoot-dry-weight) for non-target plants from seven standard greenhouse studies that used different experimental approaches (vegetative vigour vs. seedling emergence) and applied seven herbicides at different growth stages. Firstly, for each endpoint of each study, a three-parameter log-logistic model was fitted to experimental toxicity test data for each species under a Bayesian framework to get a posterior probability distribution for ER50. Then, in order to account for the uncertainty on the ER50, we explored two censoring criteria to automatically censor ER50 taking the ER50 probability distribution and the range of tested rates into account. Secondly, based on dose-response fitting results and censoring criteria, we considered input ER50 values for SSD analyses in three ways (only point estimates chosen as ER50 medians, interval-censored ER50 based on their 95% credible interval and censored ER50 according to one of the two criteria), by fitting a log-normal distribution under a frequentist framework to get the three corresponding HR5 estimates. We observed that SSD fitted reasonably well when there were at least six distinct intervals for the ER50 values. By comparing the three SSD curves and the three HR5 estimates, we shed new light on the fact that both propagating the uncertainty from the ER50 estimates and including censored data into SSD analyses often leads to smaller point estimates of HR5, which is more conservative in a risk assessment context. In addition, we recommend not to focus solely on the point estimate of the HR5, but also to look at the precision of this estimate as depicted by its 95% confidence interval

Predicting impacts of chemicals from organisms to ecosystem service delivery: A case study of insecticide impacts on a freshwater lake

Assessing and managing risks of anthropogenic activities to ecological systems is necessary to ensure sustained delivery of ecosystem services for future generations. Ecological models provide a means of quantitatively linking measured risk assessment end points with protection goals, by integrating potential chemical effects with species life history, ecological interactions, environmental drivers and other potential stressors. Here we demonstrate how an ecosystem modeling approach can be used to quantify insecticide-induced impacts on ecosystem services provided by a lake from toxicity data for organism-level endpoints. We used a publicly available aquatic ecosystem model AQUATOX that integrates environmental fate of chemicals and their impacts on food webs in aquatic environments. By simulating a range of exposure patterns,we illustrated how exposure to a hypothetical insecticide could affect aquatic species populations (e.g., recreational fish abundance) and environmental properties (e.g., water clarity) that would in turn affect delivery of ecosystem services. Different results were observed for different species of fish, thus the decision to manage the use of the insecticide for ecosystem services derived by anglers depends upon the favored species of fish. In our hypothetical shallow reservoir, water clarity was mostly driven by changes in foodweb dynamics, specifically the presence of zooplankton. In contrast to the complex response by fishing value,water clarity increasedwith reduced insecticide use,which produced amonotonic increase in value by waders and swimmers. Our study clearly showed the importance of considering nonlinear ecosystem feed backs where the presence of insecticide changed the modeled food-web dynamics in unexpected ways. Our study highlights one of the main advantages of using ecological models for risk assessment, namely the ability to generalize to meaningful levels of organization and to facilitate quantitative comparisons among alternative scenarios and associated trade-offs among them while explicitly accounting for different groups of beneficiaries

How non-standard test methods and data analysis tools can benefit to ecological risk assessment of chemicals ?

Regulation mostly relies upon the results of standard toxicity tests that have been validated for a reduced set of species and endpoints. This pragmatic strategy ensures the reliability of toxicological data. Yet, current practices might not appropriately cover the broad range of toxicant mode of action (e.g., endocrine disruptors - EDCs). In particular, the standard approach may fail to provide realistic risk forecasts when the test design is not sensitive enough to highlight toxicity and when the various standard tests provide conflicting results. Through two case studies, we explain why the standard approach may not allow assessing properly the risk of reprotoxic pesticides in invertebrates. The first case study illustrates current issues in risk assessment of EDCs. In this context, we show how non-standard partial life-cycle (PLC) tests allow identifying sensitive development phases/endpoints to EDCs (e.g., anti-androgens) along the life-cycle of Lymnaea stagnalis, a candidate species for the development of forthcoming OECD test guidelines. We also show how non-standard data analysis methods, such as mixed effect models, can be used to avoid underestimation of EDCs toxicity. The second case study illustrates how a non-standard approach can contribute to provide complementary data when standard approaches led to conflicting risk forecasts. In this context, we repeatedly exposed L. stagnalis to pulses of diquat and monitored life-cycle traits. We show how non-standard full life-cycle (FLC) tests allow assessing effective diquat concentrations more realistically and why non-standard models, such as TK-TD models, are relevant to characterise the time-course of biological responses to complex exposure patterns. For each case study, we show how to derive relevant effects criteria and include them in the regulatory risk assessment process. We then investigate whether including this additional data might modify current risk forecasts for the studied compounds. This study illustrates how non-standard test procedures of different nature may contribute to ecological risk assessment of chemicals, when standard procedure are lacking or provide conflicting results. Most importantly, the use of some simple but relevant PLC and FLC tests methods with L. stagnalis should be promoted when standard approaches are suspected to provide unrealistic risk forecasts