Messages from MARS

MARS leader Daniel Hering addresses the final project conference in Brussels. Image: Jörg Strackbein
The EU FP7 MARS Project – “Managing multiple stress for multiple benefits in aquatic ecosystems” – celebrated its final conference in Brussels last month. On the 16 and 17 January 2018, around 150 water scientists, managers and policy-makers convened in the time-honoured halls of the Museum of Natural Sciences, Brussels.
The event concluded four years of in-depth research by MARS scientists on multi-stressor effects on European surface and ground waters, highlighting the implications for Water Framework Directive (WFD) related management.

Ana Cristina Cardoso speaking to the MARS conference. Image: Jörg Strackbein.
Among the array of fascinating results generated by the MARS project, four key messages were reported at the conference.
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Message 1: Mitigating pressure-effects on aquatic ecosystems requires an understanding of multi-stressor impacts.
WFD water management is designed using the Driver-Pressure-State-Impact-Response concept. Significant pressures on aquatic ecosystems are identified first. These pressures are assumed to have impacts on ecological status of a river, lake or groundwater. Mitigation actions are then selected on the basis of these pressures (known as the “pressure-response shortcut”).
This approach may not fully account for the complex interactions and impacts of multiple stressors. As a result, MARS advocates aquatic science research that investigates the direct causes of deteriorated ecological status. Such an approach would allow for more informed management decisions targeting the actual, multi-stressor reasons for ecosystems not reaching good status.

Multi-stressor/impact relationships lie at the heart of informed river basin management. The WFD monitoring programmes generate valuable data sources for such analysis. EQR = Ecological Quality Ratio; ESS = Ecosystem Services.
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Message 2: Environmental ‘noise’ can obscure evidence from multi-stressor/impact relationships in river basins. Experiments can help unravel multi-stressor interactions and impacts.

Multi-stressor evidence at the river basin scale (most relevant for water management) is more obscure compared to the evidence gained at experimental scale (under controlled conditions) or European scale (with many and long stressor gradients).
Water managers deal with water bodies in the ‘real world’. Here, multi-stressor effects on aquatic biology often interfere with other (natural) factors like weather conditions or river flow dynamics.
Distinguishing multi-stressor effects from such complex environments is a bit like trying to identify a musical tune played in a noisy room. Nevertheless, water managers need to understand the multi-stressor combinations acting in their basin to devise appropriate mitigation measures.
Multi-stressor experiments (like those conducted by MARS in the Austrian Alps) help uncover the ‘noise-free’ pathways of multi-stressors interactions and impacts, and thus offer valuable insights for informed management decisions.
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Message 3: Multi-stressor interactions are common in rivers and lakes across Europe and need to be considered in River Basin Management. Interactions are highly context-specific, requiring targeted, localised research to inform management.
About one-third of the 156 MARS case studies studies analysed showed significant interaction effects (in paired-stressor/impact relationships). The strength of interaction effects at river basin scale is as large as at experimental scale.
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Message 4: River Basin Management in Europe will benefit from (more) data-driven analyses, modelling and interpretations which are tailor-made for the river basin to be managed.
WFD monitoring data from surface and ground waters across Europe is increasingly available, allowing researchers new opportunities to analyse multi-stressor/impact relationships. This evidence can feed into basin-specific prognostic or diagnostic models that enhance our understanding of aquatic systems, and help facilitate their effective management. Practitioners from applied aquatic science and water management can work together as interdisciplinary ‘water body doctors’.
MARS is helping create the conditions for such work by offering:
- An introduction to multiple stressors in aquatic ecosystems;
- A multi-stress analytical ‘cookbook’;
- A model selection tool;
- A diagnostic tool;
- A scenario analysis tool;
- Guidance for River Basin Management under multiple stress (coming soon).
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Sebastian Birk (right) in conversation with Angel Borja at a ‘World Cafe’ session. Image: Jörg Strackbein
Summing up, MARS researcher Sebastian Birk is hopeful about the impacts the project can continue to have, “This final conference of the MARS project inspired the renewal of our Hippocratic oath ‘first not to harm’ but to be beneficial to our water resources. We feel confident that our project built bridges towards closing the gap between science and practice when it comes to more effective water management under multiple stress.”