Assessing the feasibility and value of employing an ecosystem services approach in chemical environmental risk assessment under the Water Framework Directive

A Ross Brown,Stuart Marshall,Chris Cooper,Paul Whitehouse,Paul J Van Den Brink,Jack H Faber,Lorraine Maltby

doi:10.1016/j.scitotenv.2021.147857

Abstract

The feasibility and added value of an ecosystem services approach in retrospective environmental risk assessment were evaluated using a site-specific case study in a lowland UK river. The studied water body failed to achieve good ecological status temporarily in 2018, due in part to the exceedance of the environmental quality standard (annual average EQS) for zinc. Potential ecosystem service delivery was quantified for locally prioritised ecosystem services: regulation of chemical condition; maintaining nursery populations and habitats; recreational fishing; nature watching. Quantification was based on observed and expected taxa or functional groups within WFD biological quality elements, including macrophytes, benthic macroinvertebrates and fish, and on published functional trait data for constituent taxa. Benthic macroinvertebrate taxa were identified and enumerated before, during and after zinc EQS exceedance, enabling a generic retrospective risk assessment for this biological quality element, which was found to have good ecosystem service potential. An additional targeted risk assessment for zinc was based on laboratory-based species sensitivity distributions normalised using biotic-ligand modelling to account for site-specific, bioavailability-corrected zinc exposure. Risk to ecosystem services for diatoms (microalgae) was found to be high, while risks for benthic macroinvertebrates and fish were found to be low. The status of potential ecosystem service delivery (ESD) by fish was equivalent to high ecological status defined under the WFD, while ESD was higher for benthic macroinvertebrates than defined by WFD methods. The illustrated ecosystem services approach uses readily available data and adds significantly to the taxonomic approach currently used under the WFD by using functional traits to evaluate services that are prioritised as being important in water bodies. The main shortcomings of the illustrated approach were lack of: representation of bacteria and fungi; WFD predicted species lists for diatoms and macrophytes; site-specific functional trait data required for defining actual (rather than potential) ecosystem service delivery.

Highlights

Freshwater ecosystems provide multiple ecosystem services (Aylward et al, 2005), which have an estimated value of £39.5 billion per year in the UK alone (ONS, 2017)
A nursery is defined as a habitat that contributes more than the average, compared with other habitats, to the production of individuals of a species that recruit to adult populations (Beck et al, 2001)
The results of our study demonstrate that it is feasible to employ an ecosystem services approach in site-specific chemical environmental risk assessment by i) linking Water Framework Directive (WFD) measurement endpoints for ecological receptors to ecosystem services; ii) relating WFD measurement endpoints and assessment of potential ecosystem service delivery to reference values; iii) assessing the risk of a specific chemical pollutant to potential ecosystem service delivery

Summary

Introduction

Freshwater ecosystems provide multiple ecosystem services (Aylward et al, 2005), which have an estimated value of £39.5 billion per year in the UK alone (ONS, 2017). In Europe, 59% of freshwater molluscs and 40% of freshwater fish are threatened with extinction (IUCN, 2015). The main threats to freshwater ecosystems are habitat loss via changes in land and water use, exploitation of species, changing climates, pollution, harmful algal blooms, and invasive alien species including infectious disease organisms (Reid et al, 2019). These threats are a function of a wider set of indirect pressures that are linked to demographic, sociocultural, economic, technological and policy drivers, as well as to human conflicts and epidemics (IPBES, 2019). Assessing the risk of these threats to ecosystem service delivery is key to managing freshwater ecosystems for the benefit of people and nature

Methods

Results

Conclusion