Stéphane Pesce
email: stephane.pesce@inrae.fr

Annette Bérard

Marie-Agnès Coutellec

Mickael Hedde

Alexandra Langlais-Hesse

Floriane Larras

Sophie Leenhardt

Remi Mongruel

Dominique Munaron

Sergi Sabater

Stéphane Pesce* -Inrae

Mickaël Hedde

Linking ecotoxicological effects on biodiversity and ecosystem functions to impairment of

Keywords: Collective scientific assessment, Ecological processes, Environmental risk assessment, Expertise, Functional traits, Pesticides

à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Environmental managers and regulators increasingly recognize biodiversity as an important protection goal in environmental risk assessment (EFSA 2016a) and sustainability programs [START_REF] Glaser | Base sustainable development goals on science[END_REF][START_REF] Bach | Soil biodiversity integrates solutions for a sustainable future[END_REF]European Commission 2020;[START_REF] Tickner | Bending the curve of global freshwater biodiversity loss: an emergency recovery plan[END_REF]. In parallel, the concept of ecosystem service [START_REF] Costanza R, D'arge | The value of the World's ecosystem services and natural capital[END_REF]MEA 2005;[START_REF] Teeb | The economics of ecosystems and biodiversity: ecological and economic foundations[END_REF]) has progressively gained currency in ecosystem management and risk assessment (e.g., [START_REF] Cairns | Estimating the effects of toxicants on ecosystem services[END_REF][START_REF] Forbes | Use of the ecosystem services concept in ecological risk assessment of chemicals[END_REF][START_REF] Maltby | Ecosystem services and the protection, restoration and management of ecosystems exposed to chemical stressors[END_REF][START_REF] Forbes | A framework for predicting impacts on ecosystem services from (sub)organismal responses to chemicals[END_REF][START_REF] Maltby | Advantages and challenges associated with implementing an ecosystem services approach to ecological risk assessment for chemicals[END_REF][START_REF] Faber | Priorities and opportunities in the application of the ecosystem services concept in risk assessment for chemicals in the environment[END_REF][START_REF] Galic | Predicting impacts of chemicals from organisms to ecosystem service delivery: a case study of insecticide impacts on a freshwater lake[END_REF]. A standout example is environmental risk assessments on plant protection products (PPPs), which are defined here as synthetic and biobased pesticides (formulated products and active substances) and their transformation products. In 2010, the European Food Safety Authority (EFSA) Panel on PPPs and their residues emphasized that the ecosystem service framework was central to setting specific protection goals for this kind of substance (EFSA 2010). It served as a startpoint to the development of EFSA guidance on how to better protect biodiversity and ecosystem services against PPPs and other contaminants (EFSA 2013;2016a). Based on these works and guidances, various scientific experts from public research, regulatory authorities and the chemicals industry have evaluated the advantages, limitations, and pitfalls of the ecosystem service framework regarding current practices in environmental risk assessment and environmental monitoring (Box 1 and references therein; Van Wensem and Maltby 2013; [START_REF] Arts | An ecosystem services approach to pesticide risk assessment and risk management of non-target terrestrial plants: recommendations from a SETAC Europe workshop[END_REF][START_REF] Devos | Optimising environmental risk assessments: accounting for ecosystem services helps to translate broad policy protection goals into specific operational ones for environmental risk assessments[END_REF][START_REF] Van Wensem | Identifying and assessing the application of ecosystem services approaches in environmental policies and decision making[END_REF].

Box. 1: Non-exhaustive list of challenges that need to be resolved to implement the ecosystem service framework in environmental risk assessments of PPP.

Definition of reference values for ecosystem services [START_REF] Faber | Priorities and opportunities in the application of the ecosystem services concept in risk assessment for chemicals in the environment[END_REF]) Definition of acceptable vs unacceptable levels (i.e., magnitude) of PPP effects [START_REF] Brown | Toward the definition of specific protection goals for the environmental risk assessment of chemicals: a perspective on environmental regulation in Europe[END_REF]) Definition of clear and quantifiable protection goals and restoration targets for ecosystem service management [START_REF] Maltby | Ecosystem services and the protection, restoration and management of ecosystems exposed to chemical stressors[END_REF] Identification of key taxa/communities that drive ecosystem services [START_REF] Nienstedt | Development of a framework based on an ecosystem services approach for deriving specific protection goals for environmental risk assessment of pesticides[END_REF] Development of quantifiable indicators and relevant endpoints to evaluate the effects of PPPs on ecosystem services [START_REF] Faber | Elaborations on the use of the ecosystem services concept for application in ecological risk assessment for soils[END_REF][START_REF] Faber | Priorities and opportunities in the application of the ecosystem services concept in risk assessment for chemicals in the environment[END_REF] Consideration of trade-offs between ecosystem services, and possible antagonistic interactions of PPP with different services [START_REF] Galic | The role of ecological models in linking ecological risk assessment to ecosystem services in agroecosystems[END_REF] Development and implementation of applicable strategies and procedures to address site-specific risk assessment [START_REF] Forbes | Use of the ecosystem services concept in ecological risk assessment of chemicals[END_REF] Development and implementation of applicable strategies and procedures to transpose environmental risk assessment up to landscape scales [START_REF] Maltby | Advantages and challenges associated with implementing an ecosystem services approach to ecological risk assessment for chemicals[END_REF] The ecosystem service framework is pivotal to environmental risk assessment and integral to regulatory decision-making and the ecological relevance of environmental protection goals [START_REF] Cairns | Estimating the effects of toxicants on ecosystem services[END_REF][START_REF] Forbes | Use of the ecosystem services concept in ecological risk assessment of chemicals[END_REF][START_REF] Brown | Toward the definition of specific protection goals for the environmental risk assessment of chemicals: a perspective on environmental regulation in Europe[END_REF][START_REF] Munns | Ecosystem services in risk assessment and management[END_REF][START_REF] Maltby | Advantages and challenges associated with implementing an ecosystem services approach to ecological risk assessment for chemicals[END_REF]. Effective implementation of an ecosystem service-based environmental risk assessment of PPPs should help to protect and restore biodiversity and ecosystems against direct and indirect adverse effects of these contaminants [START_REF] Maltby | Ecosystem services and the protection, restoration and management of ecosystems exposed to chemical stressors[END_REF]. In this context, the ecosystem services approach has the potential to explicitly address the trade-off between social benefits and environmental losses from the use of PPPs on ecosystems, which is an issue that remains under-researched [START_REF] Nienstedt | Development of a framework based on an ecosystem services approach for deriving specific protection goals for environmental risk assessment of pesticides[END_REF][START_REF] Brown | Toward the definition of specific protection goals for the environmental risk assessment of chemicals: a perspective on environmental regulation in Europe[END_REF]. This is why stakeholders and policymakers are increasingly demanding critical and intelligible recommendations on the possible effects of PPPs on biodiversity and ecosystem services. As an explicit recent example, in 2019, the French Ministries for the Environment, Agriculture and Research commissioned a collective scientific assessment (CSA) to deliver this goal [START_REF] Pesce | Collective scientific assessment as a relevant tool to inform public debate and policymaking: an illustration with the effects of plant protection products on biodiversity and ecosystem services[END_REF]. This CSA concerned the terrestrial-freshwater-marine continuum and enlisted input from a panel of 46 experts in various spheres of research. The report of the main conclusions of the CSA underlined that the effects of PPPs on ecosystem services were only documented for a few services [START_REF] Pesce | Main conclusions and perspectives from the collective scientific assessment of the effects of plant protection products on biodiversity and ecosystem services along the landsea continuum in France and French overseas territories[END_REF], mainly water quality, human food quality (animal-source and plant-source), plant production, biological control, and pollination. The CSA pointed out, for instance, that services provided by soil ecosystems, as well as cultural services, have received little attention in the scientific literature dealing with the risks and effects of PPPs [START_REF] Pesce | Main conclusions and perspectives from the collective scientific assessment of the effects of plant protection products on biodiversity and ecosystem services along the landsea continuum in France and French overseas territories[END_REF]. The inclusion of ecosystem services in chemical risk assessment is gaining increasing currency within a prominent group of European researchers who are very active on the topic (in collaboration with a variety of stakeholders; [START_REF] Maltby | Applying ecosystem services principles to the derivation of freshwater environmental quality standards[END_REF], as illustrated by their recent articles [START_REF] Brown | Assessing the feasibility and value of employing an ecosystem services approach in chemical environmental risk assessment under the Water Framework Directive[END_REF][START_REF] Faber | Identifying ecological production functions for use in ecosystem services-based environmental risk assessment of chemicals[END_REF][START_REF] Van Den Brink | The use of ecological models to assess the effects of a plant protection product on ecosystem services provided by an orchard[END_REF][START_REF] Oginah | Linking freshwater ecotoxicity to damage on ecosystem services in life cycle assessment[END_REF]. Note, however, that the consequences of ecotoxicological effects of PPPs (or other chemicals) on ecosystem services are only addressed by a handful of people within the international ecotoxicology community. To overcome this issue, the panel of experts engaged in the CSA highlighted the need for this community to have a shared set of definitions and concepts concerning both (i) the main processes governing the relationships between biodiversity, ecological processes, ecosystem functions, and ecosystem services (for which consensual definitions are proposed in Box 2) and (ii) the classification of ecosystem functions and their linkages with ecological processes investigated in ecotoxicology. A consensus set of shared definitions could lend huge impetus to approaches advocated in recent years, which are based on the use of ecological models [START_REF] Van Den Brink | The use of ecological models to assess the effects of a plant protection product on ecosystem services provided by an orchard[END_REF] or evidence-based logic chains [START_REF] Hayes | Evidence-based logic chains demonstrate multiple impacts of trace metals on ecosystem services[END_REF][START_REF] Maltby | Assessing chemical risk within an ecosystem services framework: implementation and added value[END_REF][START_REF] Faber | Identifying ecological production functions for use in ecosystem services-based environmental risk assessment of chemicals[END_REF] to assess and predict impacts of chemicals on ecosystem services.

Box. 2: Definitions of biodiversity, ecological processes, ecosystem functions, and ecosystem services that were adopted by the experts involved in the collective scientific assessment Biodiversity follows the Convention on Biological Diversity definition (United Nations 1992). As such, biodiversity is "the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species, and of ecosystems." This definition includes the composition, structure and variety of specific species or habitats, plus the abundance and biomass of species, their functional traits, and their genetic composition and identity [START_REF] Marselle | Pathways linking biodiversity to human health: a conceptual framework[END_REF].

Ecological processes are activities that result from interactions among organisms and between organisms and their environment [START_REF] Martinez | Defining and measuring functional aspects of biodiversity[END_REF].

Ecosystem functions are sets of interconnected ecological processes at work within an ecosystem. They may or may not contribute to ecosystem services [START_REF] Lovett | Ecosystem function in heterogeneous landscapes[END_REF][START_REF] Garland | A closer look at the functions behind ecosystem multifunctionality: a review[END_REF].

Ecosystem services are the socioeconomic benefits to human populations and societies provided by healthy ecosystems (adapted from MEA 2005).

The relationship between biodiversity and ecosystem functions has been extensively explored in the ecology of "natural" or "weakly anthropized" ecosystems (van der Plas 2019), but its intersection with ecotoxicological pressure has been under-researched [START_REF] Rumschlag | Consistent effects of pesticides on community structure and ecosystem function in freshwater systems[END_REF]. Functional endpoints used in ecotoxicological studies tend to refer to ecological processes rather than to ecosystem functions. In this context, we first provide an analysis of the literature on the on the biodiversityecological processes-ecosystem functions nexus in order to propose a conceptual scheme that is specifically applicable to PPPs. We then propose a definition and classification of ecosystem functions that are potentially impacted by PPPs in an effort to address the current inconsistencies (e.g., [START_REF] Costanza R, D'arge | The value of the World's ecosystem services and natural capital[END_REF][START_REF] Groot | A typology for the classification, description and valuation of ecosystem function, goods and services[END_REF][START_REF] Pettorelli | Satellite remote sensing of ecosystem functions: opportunities, challenges and way forward[END_REF][START_REF] Armoškaitė | Establishing the links between marine ecosystem components, functions and services: an ecosystem service assessment tool[END_REF][START_REF] Garland | A closer look at the functions behind ecosystem multifunctionality: a review[END_REF]. Finally, we break new ground by exploring perceptions on the possible links between these categories of ecosystem functions and ecosystem services among a sub-panel of the CSA's scientific experts (n=17) in various fields of environmental sciences, before concluding that a shared and harmonized framework could help extend the scientific knowledge that informs decision-making and policymaking.

Conceptual relationships between biodiversity, ecological processes, and ecosystem functions under PPP-induced pressure

Assessment of the relationships between biodiversity and ecosystem functioning has been one of the most active fields of research in ecology (e.g., Schulze and Mooney 1993;[START_REF] Balvanera | Quantifying the evidence for biodiversity effects on ecosystem functioning and services[END_REF][START_REF] Cardinale | Effects of biodiversity on the functioning of trophic groups and ecosystems[END_REF][START_REF] Loreau | Linking biodiversity and ecosystems: towards a unifying ecological theory[END_REF][START_REF] Tilman | Biodiversity and ecosystem functioning[END_REF][START_REF] Eisenhauer | A multitrophic perspective on biodiversity-ecosystem functioning research[END_REF][START_REF] Van Der Plas | Biodiversity and ecosystem functioning in naturally assembled communities[END_REF]. At present, there is a broad consensus that the dynamics of biodiversity are not entirely governed by random processes. At community level, assembly, structure, and diversity all result from the combined effects of ecological drift and deterministic processes [START_REF] Hubbell | The unified neutral theory of biodiversity and biogeography[END_REF][START_REF] Tilman | Niche tradeoffs, neutrality, and community structure: a stochastic theory of resource competition, invasion, and community assembly[END_REF][START_REF] De Meester | Evolving perspectives on monopolization and priority effects[END_REF][START_REF] Schumacher | Frequency dependence and ecological drift shape coexistence of species with similar niches[END_REF]. Likewise, at species level, population eco-evolutionary dynamics are shaped by both random (genetic drift) and non-random (selection mode and intensity, mutation rate, mating system) processes (see [START_REF] Hartl | Principles of population genetics[END_REF]. Environmental deterioration, such as that caused by chemical contamination (including PPPs), can drive a population to decline or even go extinct (maladaptation) or conversely to recover through plasticity, dispersion, or rapid evolutionary adaptation (e.g., antibiotic and pesticide resistance, which are two typical cases of evolutionary rescue; Bell 2017). Therefore, whatever the level of investigation, non-random (deterministic) factors and processes need to be explicitly addressed when empirically testing theoretical hypotheses related to the dynamics of biodiversity under environmental change. Propelled by findings and lessons from a decade of intensive fundamental research, a new generation of research on biodiversity and ecosystem functioning emerged [START_REF] Naeem | Biodiversity, ecosystem-functioning, and human wellbeing[END_REF]) that was characterized by more functional approaches (trait-based functional diversity and mechanisms of ecosystem functioning, and the multitrophic dimension) and hypotheses (trait-based extinction probability, empirical extinction scenarios, net biodiversity effect partitioning). Today's research has also become more predictive (e.g., wider spatial and temporal scales, theory development, metacommunity dynamics) and now encompasses issues directly related to human impact and ecosystem services [START_REF] Naeem | Biodiversity, ecosystem-functioning, and human wellbeing[END_REF]). Recent developments now make it possible to explain the biodiversity-ecosystem functioning relationship across time and space [START_REF] Isbell | Quantifying effects of biodiversity on ecosystem functioning across times and places[END_REF]. It is therefore patently quite clear that the impacts of PPPs on biodiversity, ecosystem functions and ecosystem services should be assessed by considering the non-random direct and indirect pressure that these impacts exert on biodiversity [START_REF] De Laender | The contribution of intra-and interspecific tolerance variability to biodiversity changes along toxicity gradients[END_REF], 2016;[START_REF] Halstead | Community ecology theory predicts the effects of agrochemical mixtures on aquatic biodiversity and ecosystem properties[END_REF][START_REF] Malaj | Organic chemicals jeopardize the health of freshwater ecosystems on the continental scale[END_REF][START_REF] Baert | The consequences of nonrandomness in species-sensitivity in relation to functional traits for ecosystem-level effects of chemicals[END_REF][START_REF] Rumschlag | Consistent effects of pesticides on community structure and ecosystem function in freshwater systems[END_REF]. In this context, here, we propose a conceptual scheme integrating biodiversity, ecological processes, and ecosystem functions under the effects of PPPs (Fig. 1).

Fig. 1: Expected effects of plant protection products on biodiversity, ecological processes, and ecosystem functions through inter-relationships

This scheme first integrates the direct effects of PPPs on biodiversity, including intraspecific, interspecific, and functional biodiversity, which stem from the use, fate, and bioavailability of PPPs in the environment and the resulting exposure of organisms. These effects result from the combination of the toxicity and mechanisms of action of the PPP substances and substance-substance interactions, as well as biological sensitivity and its distribution within and across species (Fig. 1; [START_REF] Blanck | Pollution-induced community tolerance -a new ecotoxicological tool[END_REF][START_REF] Vinebrooke | Impacts of multiple stressors on biodiversity and ecosystem functioning: the role of species co-tolerance[END_REF][START_REF] Johnston | Contaminants reduce the richness and evenness of marine communities: a review and meta-analysis[END_REF][START_REF] De Laender | The contribution of intra-and interspecific tolerance variability to biodiversity changes along toxicity gradients[END_REF][START_REF] Kattwinkel | Recovery of aquatic and terrestrial populations in the context of European pesticide risk assessment[END_REF][START_REF] Mensens | Stressor-induced biodiversity gradients: revisiting biodiversity-ecosystem functioning relationships[END_REF]EFSA 2016b). Species demonstrate adaptive capacities (acclimation, tolerance, resistance, resilience, recovery) that extend through various biological scales (populations, communities) and timescales (rapid and reversible physiological adaptation through developmental and phenotypic plasticity vs longer-term adaptation through selective evolutionary processes). Toxic effects can also have indirect consequences on biodiversity by altering species-species interactions both within and between trophic levels (Fig. 1; [START_REF] Fleeger | Indirect effects of contaminants on aquatic ecosystems[END_REF][START_REF] Halstead | Community ecology theory predicts the effects of agrochemical mixtures on aquatic biodiversity and ecosystem properties[END_REF][START_REF] Saaristo | Direct and indirect effects of chemical contaminants on the behaviour, ecology and evolution of wildlife[END_REF][START_REF] Fleeger | How do indirect effects of contaminants inform ecotoxicology? A review[END_REF]. The non-random effects of PPPs on biodiversity therefore influence key ecological processes that mainly depend on the functional role of sensitive species and the degree of functional redundancy between species (Fig. 1; [START_REF] Allison | Resistance, resilience, and redundancy in microbial communities[END_REF][START_REF] Cardinale | Biodiversity loss and its impact on humanity[END_REF][START_REF] Díaz | Functional traits, the phylogeny of function, and ecosystem service vulnerability[END_REF][START_REF] Bardgett | Belowground biodiversity and ecosystem functioning[END_REF][START_REF] De Laender | Reintroducing environmental change drivers in biodiversity-ecosystem functioning research[END_REF][START_REF] Baert | The consequences of nonrandomness in species-sensitivity in relation to functional traits for ecosystem-level effects of chemicals[END_REF]). These non-random effects on biodiversity may affect ecosystem functioning to a greater (e.g., when impacting keystone species) or lower degree (e.g., where there is high functional redundancy) than random ones [START_REF] De Laender | Reintroducing environmental change drivers in biodiversity-ecosystem functioning research[END_REF]. Most PPPs are designed to specifically target biological groups that directly contribute to ecological processes (Fig. 1). Photosystem-inhibitor herbicides (such as triazines and phenylureas) are good examples of PPPs that directly act on photosynthesis and primary production [START_REF] Black | Effects of herbicides on photosynthesis[END_REF]. Such targeted functional effects can strongly influence biodiversity-ecosystem function relationships through mechanisms that revolves around feedback from ecological processes and ecosystem functions to biodiversity (Fig. 1). These relatively unknown feedbacks [START_REF] Duncan | The quest for a mechanistic understanding of biodiversity-ecosystem services relationships[END_REF][START_REF] Grace | Integrative modeling reveals mechanisms linking productivity and plant species richness[END_REF][START_REF] Qiu | Ecosystem functions including soil organic carbon, total nitrogen and available potassium are crucial for vegetation recovery[END_REF]; van der Plas 2019) are an important factor for achieving biodiversity conservation objectives [START_REF] Xiao | The value of understanding feedbacks from ecosystem functions to species for managing ecosystems[END_REF]) and enhancing our current understanding of their role in the ecological processes that affect the bioavailability of PPPs (e.g., biodegradation or bioturbation) (Fig. 1; [START_REF] Chaplain | Fate of pesticides in soils: toward an integrated approach of influential factors[END_REF][START_REF] Bundschuh | The mode of bioturbation triggers pesticide remobilization from aquatic sediments[END_REF]. Moreover, there is still an unaddressed need for ecotoxicological indicators that can be linked to ecosystem functions rather than to ecological processes [START_REF] Heink | What are indicators? On the definition of indicators in ecology and environmental planning[END_REF][START_REF] Thomsen | Soil ecosystem health and services -evaluation of ecological indicators susceptible to chemical stressors[END_REF][START_REF] Forbes | A framework for predicting impacts on ecosystem services from (sub)organismal responses to chemicals[END_REF][START_REF] Faber | Priorities and opportunities in the application of the ecosystem services concept in risk assessment for chemicals in the environment[END_REF][START_REF] Garland | A closer look at the functions behind ecosystem multifunctionality: a review[END_REF].

Definition and classification of ecosystem functions potentially impacted by PPPs

Several classifications of ecosystem functions and services have been proposed in the past (e.g., [START_REF] Costanza R, D'arge | The value of the World's ecosystem services and natural capital[END_REF][START_REF] Groot | A typology for the classification, description and valuation of ecosystem function, goods and services[END_REF], 2012;CGDD 2010;[START_REF] Banerjee | Ecological processes, functions and ecosystem services: inextricable linkages between wetlands and agricultural systems[END_REF][START_REF] Liquete | Current status and future prospects for the assessment of marine and coastal ecosystem services: a systematic review[END_REF][START_REF] Pettorelli | Satellite remote sensing of ecosystem functions: opportunities, challenges and way forward[END_REF][START_REF] Van Der Plas | Biodiversity and ecosystem functioning in naturally assembled communities[END_REF][START_REF] Garland | A closer look at the functions behind ecosystem multifunctionality: a review[END_REF]. Certain ecosystem functions are sometimes termed "intermediate ecosystem services" [START_REF] Boyd | What are ecosystem services? The need for standardized environmental accounting units[END_REF][START_REF] Munns | Ecosystem services as assessment endpoints for ecological risk assessment[END_REF][START_REF] Fisher | Defining and classifying ecosystem services for decision making[END_REF][START_REF] Forbes | A framework for predicting impacts on ecosystem services from (sub)organismal responses to chemicals[END_REF]), but this terminology has been questioned [START_REF] Potschin-Young | Intermediate ecosystem services: an empty concept?[END_REF]. In 2021, Garland et al. proposed a classification based on an extensive meta-analysis of 268 studies dealing with ecosystem multifunctionality [START_REF] Byrnes | Investigating the relationship between biodiversity and ecosystem multifunctionality: challenges and solutions[END_REF][START_REF] Delgado-Baquerizo | Microbial diversity drives ecosystem multifunctionality in terrestrial ecosystems[END_REF][START_REF] Gamfeldt | Revisiting the biodiversity-ecosystem multifunctionality relationship[END_REF]. They found that research to date had considered a large number of ecosystem functions but without any attempt to harmonize the terminology and underlying concepts used [START_REF] Garland | A closer look at the functions behind ecosystem multifunctionality: a review[END_REF]). The resulting semantic inconsistencies have brought about redundant, ambiguous, and imprecise (if not controversial) term usage. To address this issue, we propose a classification based on 12 main categories of ecosystem functions that can be directly linked with the ecological processes used as functional endpoints in the assessment of PPP impacts in terrestrial, freshwater, and marine ecosystems (Table 1). This new classification departs from the classification published by De [START_REF] Groot | A typology for the classification, description and valuation of ecosystem function, goods and services[END_REF] and revisited by [START_REF] Pettorelli | Satellite remote sensing of ecosystem functions: opportunities, challenges and way forward[END_REF]. Following [START_REF] Pettorelli | Satellite remote sensing of ecosystem functions: opportunities, challenges and way forward[END_REF], cultural service functions were excluded on the grounds that they can be directly considered ecosystem services. The literature corpus mobilized during the CSA (i.e., about 4500 international publications) reported risks and/or effects of various PPPs on at least 8 of the 12 proposed categories [START_REF] Pesce | Main conclusions and perspectives from the collective scientific assessment of the effects of plant protection products on biodiversity and ecosystem services along the landsea continuum in France and French overseas territories[END_REF]. [START_REF] Groot | A typology for the classification, description and valuation of ecosystem function, goods and services[END_REF] and [START_REF] Pettorelli | Satellite remote sensing of ecosystem functions: opportunities, challenges and way forward[END_REF]

Classification of ecosystems services

The notion of ecosystem services emerged in the 1970s, where it was used by economists to conceptualize the link between the functions of nature and the benefits that society derives from it.

The first author to refer to the concept was [START_REF] Schumacher | Frequency dependence and ecological drift shape coexistence of species with similar niches[END_REF] who talked about "natural capital," but the term "ecosystem services" itself was not coined until a few years later (see for example [START_REF] Westman | How much are nature's services worth?[END_REF][START_REF] Ehrlich | Extinction: the causes and consequences of the disappearance of species, Random House[END_REF] when it quickly became associated with advocacy for protecting ecosystems, given that most of the services they provide have no substitute [START_REF] Ehrlich | Extinction, substitution, and ecosystem services[END_REF]. Later on, seminal papers such as [START_REF] Daily | Nature's services: societal dependence on natural ecosystems[END_REF] and [START_REF] Costanza R, D'arge | The value of the World's ecosystem services and natural capital[END_REF] went on to lend the "ecosystem services" concept, a multidisciplinary and global dimension, prompting the United Nations to coordinate several related projects and initiatives, such as the Millennium Ecosystem Assessment (MEA;2000-2005), The Economics of Ecosystems and Biodiversity (TEEB;[START_REF] Boyd | What are ecosystem services? The need for standardized environmental accounting units[END_REF]-2011), and the Intergovernmental Science-Policy Platform on the Biodiversity and Ecosystem services (IPBES; 2012-today). The main objectives of these initiatives were to provide a conceptual framework for the notion of ecosystem service (MEA), to evaluate the contribution of these ecosystem services to society (TEEB), and to inform and guide government policy through evidence-based science on each of the ecosystem services previously defined by the MEA and TEEB (IPBES). Ecosystem services have been given several more or less similar definitions. While all of these definitions converge to emphasize the contribution of ecosystem services to our well-being, they sometimes diverge on the dynamics that need to be considered. [START_REF] Daily | Nature's services: societal dependence on natural ecosystems[END_REF] asserted that ecosystem services are processes that support our well-being, whereas [START_REF] Costanza R, D'arge | The value of the World's ecosystem services and natural capital[END_REF] defined them as the goods and services resulting from these processes. As mentioned in Box 2 and in [START_REF] Pesce | Main conclusions and perspectives from the collective scientific assessment of the effects of plant protection products on biodiversity and ecosystem services along the landsea continuum in France and French overseas territories[END_REF], the definition of ecosystem services used in our CSA (i.e., "the socioeconomic benefits to human populations and societies provided by healthy ecosystems") is derived from that initially proposed by the MEA (2005), which defined ecosystem services as the benefits that humans derive from ecosystems (without making the distinction between the processes and the goods and services produced) and classified them into four categories, three of which directly impact human well-being (provisioning services providing food or energy, regulating services enabling, for example, air or water purification, and cultural services including recreational spaces offered by ecosystems) and a fourth that indirectly impacts it (supporting services that enable processes like nutrient cycling or soil formation to continue providing other ecosystem services). The MEA-defined scheme of ecosystem services was subsequently remobilized in international projects such as the IPBES and TEEB frameworks, but the category of "supporting" services disappeared [START_REF] Díaz | The IPBES conceptual framework -connecting nature and people[END_REF] as they were considered ecological processes (TEEB 2010).

Because most of its contributors were members of the conservation biology movement, the ecosystem services approach initially disregarded the notion of "dis-services" [START_REF] Campagne | Looking into Pandora's Box: ecosystem disservices assessment and correlations with ecosystem services[END_REF]). However, from the ecosystem services approach perspective, the impact of pests on food production is a "disservice" of the ecosystem to humans [START_REF] Rasmussen | From food to pest: conversion factors determine switches between ecosystem services and disservices[END_REF]. A society that uses PPPs has therefore at least implicitly chosen to pursue the maximization of food production by reducing the short-term impacts of pest species on that service. It is only in the longer term that the negative impacts of PPP use on other services become apparent, notably in certain regulatory services that are useful to agriculture, such as pollination or soil formation, or cultural services that are dependent on the quality of the environment.

There is no one consensus approach for categorizing ecosystem services. Nevertheless, the approach initiated by the MEA and developed in the later IPBES and TEEB framework seems to be gaining wider adoption by the EU decision-makers. The European Environment Agency proposed a Common International Classification of Ecosystem Services (CICES; https://cices.eu) based on the ecosystem service cascade [START_REF] Potschin | Ecosystem services: exploring a geographical perspective[END_REF]. This system links ecological processes and functions to end-services, i.e., the MEA's three direct-impact categories of ecosystem services (provisioning services, regulating and maintenance services, and cultural services).

To address its aim of clearly outlining the knowledge, controversies, and gaps in understanding surrounding impacts of PPPs on ecosystem services, the expert panel working on the CSA (see [START_REF] Pesce | Collective scientific assessment as a relevant tool to inform public debate and policymaking: an illustration with the effects of plant protection products on biodiversity and ecosystem services[END_REF]) used the most recent version of the CICES classification (version 5.1.; Haines-Young and Potschin 2018).

Perceptions of the relationships between ecosystem functions and ecosystem services

Here, we used a perceptions survey to explore the possible links between the ecosystem functions potentially impacted by PPPs (based on the classification described in Table 1) and the groups of biotic and abiotic ecosystem services defined under the CICES classification (version 5.1.;[START_REF] Haines-Young | Common International Classification of Ecosystem Services (CICES) V5.1 and Guidance on the Application of the Revised Structure[END_REF]. For that purpose, we established a sub-panel of 17 of the CSA-team scientific experts (see the acknowledgements section) covering a wide range of environmental disciplines that connect to the fate and impact of PPPs in soil and aquatic ecosystems (environmental chemistry, agronomy, microbial ecotoxicology, aquatic ecotoxicology, terrestrial ecotoxicology, ecology and evolution, and chemical fate and effect modeling). Each expert was asked to express his/her opinion, based on his/her own knowledge, experience, and perception, on ecosystem function-ecosystem service linkages. For each of the 218 combinations of ecosystem function group (n=12) × ecosystem service group (n=18), four possible responses were offered: (i) direct link, (ii) indirect link, (iii) no link, or (iv) no opinion.

Accepted manuscript 10 Direct or indirect links did not carry any mention of whether the ecosystem function-ecosystem service relationship had to be positive or negative. Figure 2 illustrates the results obtained for the provisioning services (Fig. 2A), regulating and maintenance services (Fig. 2B), and cultural (Fig. 2C) services. Whatever the proposed combination, at least two experts identified possible direct and/or indirect links between the ecosystem service categories and the ecosystem function categories. Moreover, the majority of the experts consulted (i.e., at least 9/17) considered that about 55% of the combinations concerning provisioning services (Fig. 2A) and regulating and maintenance services (Fig. 2B) were characterized by direct links with the proposed categories of ecosystem functions. This percentage reached 95% when also considering the indirect links. However, a general consensus (i.e., identical responses among experts) emerged in very few cases (n=9, <5% of the total combinations), and only in three categories of provisioning services (i.e., "Genetic material from plants, algae, fungi, animals or organisms," "Wild plants (terrestrial and aquatic) for nutrition, materials or energy," and "Wild animals (terrestrial and aquatic) for nutrition, materials or energy"; Fig. 2A) and two categories of regulating and maintenance services ("Regulation of baseline flows and extreme events" and "Mediation of wastes or toxic substances of anthropogenic origin by living processes"; Fig. 2B). Furthermore, each time, the consensus was always towards the existence of direct links.

Fig. 2: Perceptions of a panel of experts in environmental sciences (n=17) on the links between the ecological function (EF) categories proposed in

There was much higher variability in the responses on cultural services (Fig. 2C), for which a high percentage of "no opinion" responses was observed, in particular for the categories "Spiritual, symbolic and other interactions with the natural environment" and "Other biotic characteristics that have a non-use value."

The results of this exercise indicate that it is possible to establish potential relationships between ecosystem functions and services, but that further efforts are needed to clarify the direct vs indirect nature of these links, and that there is still a great deal of subjectivity that can sometimes generate very different perceptions among experts. Moreover, the general picture of expert perception shows that the nature of the link is mainly profiled by service rather than by function (i.e., in most cases presented in Fig. 2, the percentages obtained are fairly homogeneous in the rows but more heterogeneous in the columns). This suggests that few services are linked to only part of the functions, and that it is above all the nature of the service that determines whether the link with most of the functions is direct or indirect. In terms of risk prevention, this implies that prioritizing particular services would in no way lead to prioritizing particular functions, given that each service relies on a set of functions and each function has consequences on a set of services.

Conclusions

Effective implementation of ecosystem service-based environmental risk assessments on PPPs could lead to better protection for ecosystems affected by the direct and indirect adverse effects of PPP contaminants. This topic is increasingly being discussed in the recent scientific literature, but there is still a substantial gap between most ecotoxicological studies and the evaluation of potential ecotoxicological consequences on ecosystem services. Several authors have recently proposed to develop ecological models or evidence-based logic chain approaches, but it is likely that the ecotoxicology community can only appropriate these approaches if it learns to accept and shares a backbone set of concepts and definitions related to ecological processes, ecosystem functions, and ecosystem services. A shared set of concepts and definitions could help harmonize and extend the science that informs decision-making and policy-making, and ultimately help to better address the trade-off between social benefits and environmental losses caused by the use of PPPs on ecosystems.

In addition, the development of shared and standardized methods could make it possible to establish quantifiable indicators and relevant endpoints to evaluate the effects of PPPs on ecosystem services. With this in mind, the recent establishment of a working group at the International Organization for Standardization (ISO) to specifically focus on the assessment of soil functions and related-ecosystem services (ISO/TC 190/WG3), with the aims of proposing definitions and conceptual Framework (ISO/CD 18718) as well as indicators and methods (ISO/CD 18721), offers promising prospects for filling the knowledge gaps pointed out by the CSA about the effects of PPPs on soil ecosystem services [START_REF] Pesce | Main conclusions and perspectives from the collective scientific assessment of the effects of plant protection products on biodiversity and ecosystem services along the landsea continuum in France and French overseas territories[END_REF]).

Table 1 :

 1 Proposed classification of ecosystem functions potentially impacted by PPPs [adapted from

  ], and illustrative (non-exhaustive) list of related functional endpoints employed in ecotoxicology

				vegetation biomass, aquatic
				biomass (e.g. coral reefs,
				seagrasses, mangrove
				vegetation), microbial filament
		Ecosystem function	Definition	Examples of functional endpoints production and
		category		used in ecotoxicology exopolysaccharide production
	1 10 Dispersion of Gas regulation	Production and consumption of gas and Role of vegetation and biota in the	Photosynthesis, respiration, Sexual (e.g. pollination) and
		propagules in	the regulation of gas exchanges among movement of propagules including floral	methanogenesis, methanotrophy, vegetative reproduction of plants,
		terrestrial and	different environmental compartments gametes and seeds, aquatic/marine	denitrification, nitrogen fixation, spore and akinete production,
		aquatic ecosystems	and with the atmosphere spores, eggs and larvae	evapotranspiration transport of propagules by
	2	Dissipation and	Filtration, buffering, sequestration and	Biodegradation/phytodegradation terrestrial and aquatic organisms
	mitigation of 11 Provision and	degradation of chemical and biological Provision and preservation of biodiversity	potential, enzymatic activity, Population/community dynamics,
		contaminants and maintenance of	contaminants and wastes and interactions within biotic	exopolysaccharide production trophic interactions, competition,
		wastes in terrestrial biodiversity and	communities to maintain ecosystem	facilitation, parasitism, symbiosis,
		and aquatic biotic interactions in	functioning, contain the impact of	genetic potential, nutrient,
		ecosystems terrestrial and	outbreaks/blooms (e.g. by controlling	hormone and biocide production
	3	Resistance to aquatic ecosystems	Mitigation of and ability to resist both populations of potential pests and disease	Aboveground (cover) and
		disturbance	environmental (e.g. heatwaves, fires, vectors), ensure the production and use of	belowground (root systems)
			storms, floods, mudflows, avalanches) and natural materials (i.e. biological and	terrestrial vegetation biomass,
			human-driven (e.g. pollution) disturbances genetic resources) that organisms can use	aquatic biological-structure
			for health, and contribute to a self-	biomass (e.g. coral reefs,
			maintaining diversity of organisms	seagrasses, mangrove
			developed over evolutionary time	vegetation), pigment production,
			(capable of continuing to change)	exopolysaccharide production,
	12 Provision and	Provision of suitable living space for wild	and mucilage production Bioturbation by soil and sediment
	4	Water retention in maintenance of	Retention and storage of water in soil and biotic communities and individual species.	Bioturbation by soil and sediment organisms, terrestrial and aquatic
		soil and sediment habitats and	sediment to preserve freshwater Also includes the provision of suitable	organisms, exopolysaccharide and vegetation biomass (aboveground
		biotopes in	resources breeding, reproduction, nursery, refugia	mucilage production, root and belowground), terrestrial and
		terrestrial and	and corridors in natural and semi-natural	architecture aquatic biogenic structures
	5	Water flow aquatic ecosystems	Regulation of runoff and water discharge ecosystems (connectivity)	Bioturbation by soil and sediment
		regulation		organisms, exopolysaccharide and
				mucilage production, root
				architecture
	6	Albedo and	Local mitigation of the effects of climate	Vegetation biomass and cover,
		reflection	change (including extreme events)	macroalgae and phytoplankton
				biomass, pigment production
	7	Production and input	Production and dispersion of biomass and	Primary production, secondary
		of organic matter in	organic matter that can serve as energy	production
		terrestrial and	sources in food webs
		aquatic ecosystems
	8	Nutrient regulation	Decomposition of organic matter and	Methanogenesis, methanotrophy,
		in terrestrial and	nutrient transport, storage and recycling	nitrification, denitrification,
		aquatic ecosystems		nitrogen fixation, sulfur
				oxidation/reduction, phosphorus
				solubilization, enzymatic
				activities, particulate organic
				matter decomposition
	9	Formation and	Role of vegetation and biota in the	Bioturbation by soil and sediment
		maintenance of soil	formation and maintenance of soil and	organisms, aboveground (cover)
		and sediment	sediment structure (including shorelines	and belowground (root systems
		structure	and coasts)	and mucilage) terrestrial

Acknowledgments

The authors thank (i) all the experts involved in the CSA that served for this paper, and especially those who, together with some of the authors, gave their perception of the links between ecosystem functions and services, namely Drs Marcel Amichot, Philippe Berny, Stéphane Betoulle, Michael Coeurdassier, Olivier Crouzet, Laure Mamy, Sylvie Nelieu, Wilfried Sanchez, Sabine Stachowski-Haberkorn, and Julien Tournebize; (ii) the French Ministries for the Environment, Research and Agriculture, who commissioned this CSA; (iii) the INRAE directorate for science strategy, and the Ifremer general directorate; (iv) Guy Richard, head of the INRAE Directorate for Expertise, Foresight and Advanced Studies (DEPE); and (v) the librarians responsible for compiling the bibliographic corpus (Anne-Laure Achard, Morgane Le Gall, and Sophie Le Perchec).

This collective scientific assessment received financial support from the French Office for . AP, AB, MAC, MH, ALH, FL, SL, RM, DM, SS, and NG contributed to subsequent revisions to the manuscript and approved the final