Towards a general framework for the assessment of interactive effects of multiple stressors on aquatic ecosystems: Results from the Making Aquatic Ecosystems Great Again (MAEGA) workshop

Abstract

A workshop was held in Wageningen, The Netherlands, in September 2017 to collate data and literature on three aquatic ecosystem types (agricultural drainage ditches, urban floodplains, and urban estuaries), and develop a general framework for the assessment of multiple stressors on the structure and functioning of these systems. An assessment framework considering multiple stressors is crucial for our understanding of ecosystem responses within a multiply stressed environment, and to inform appropriate environmental management strategies. The framework consists of two components: (i) problem identification and (ii) impact assessment. Both assessments together proceed through the following steps: 1) ecosystem selection; 2) identification of stressors and quantification of their intensity; 3) identification of receptors or sensitive groups for each stressor; 4) identification of stressor-response relationships and their potential interactions; 5) construction of an ecological model that includes relevant functional groups and endpoints; 6) prediction of impacts of multiple stressors, 7) confirmation of these predictions with experimental and monitoring data, and 8) potential adjustment of the ecological model. Steps 7 and 8 allow the assessment to be adaptive and can be repeated until a satisfactory match between model predictions and experimental and monitoring data has been obtained. This paper is the preface of the MAEGA (Making Aquatic Ecosystems Great Again) special section that includes three associated papers which are also published in this volume, which present applications of the framework for each of the three aquatic systems.

Metabolite Changes in an Estuarine Annelid Following Sublethal Exposure to a Mixture of Zinc and Boscalid

“…Alternatively, the differences in metabolite abundance could be due to the addition of boscalid, following a week of zinc exposure. In the latter case, the allocation of resources by annelids to respond to zinc exposure was already underway when the fungicide was added; therefore, the response to boscalid was not as large as might be expected [36,37,38,39,40,41,42,43,44,45,46,47,48].…”

“…Changes in the TCA cycle, intermediates of the urea cycle, and the glycine, serine, and threonine cycle, are common responses to external stress seen in many studies [38,43]. An assessment framework considering multiple stressors is critical for our understanding of ecosystem responses within a stressed environment, and to inform appropriate environmental management strategies [44]. Mixture toxicity is an ongoing global issue that requires further investigation of molecular responses of organisms to complex chemical mixtures if we are to effectively manage anthropogenic contamination occurring in environments such as urban estuaries.…”

Unravelling the effect of multiple stressors on ecological structure of littoral lake macroinvertebrates

“…There have been few studies that have explicitly disentangled the effects of multiple pressures using littoral lake macroinvertebrates (Johnson et al, 2018). Indeed, a general framework for the assessment of multiple stressors on the structure and functioning of aquatic systems is lacking (Van den Brink et al, 2019). Benthic invertebrates are currently the most widely used group to detect the impact of hydromorphological alterations in European lakes with sufficiently strong evidence of cause–response relationship (Poikane et al, 2020), although some taxa's sensitivity to nutrient gradients can obscure their response to shoreline modifications.…”

Potential threats to smallmouth bass (Micropterus dolomieu) in the Juniata River Basin, Pennsylvania, USA

“…In the six tributaries we assessed, all but one of them had multiple EDCs present at detectable levels (Table 2). While extensive EDC overlap is not uncommon, a chemical-by-chemical approach to EDCs has been largely criticized, and a more cumulative approach is advised for EDC risk assessment (Kortenkamp 2007;Alvarez et al 2009;Van den Brink et al 2019). Further, the lack of field research on the 'potency' of individual EDCs on individual fish species therefore makes it difficult to justly determine the biological risk of overlapping EDCs on SMB.…”