The marine environment constantly experiences pressures. Originating from both natural and anthropogenic sources, these pressures rarely occur in isolation.
In order to achieve Good Environmental Status (GES) in EU waters, the Marine Strategy Framework Directive (MSFD) addresses the pressures created by human activity. The challenges faced by researchers when assessing individual pressures and their impact on the ecosystem are great, but , the challenges increase hugely when considering the combined impact of pressures acting in parallel.
Cumulative impact assessment (CIA) is an emerging research theme and one that easily finds a home within the integrated ecosystem assessment (IEA) approach adopted by ICES in its Strategic Plan. CIAs are required by EU Member States in order to assess and manage the marine ecosystems impacts of multiple human activities.
EU Member States are currently developing MSFD programme of measures (PoMs) which will define actions that need to be taken if GES is to be realised. The aim is to find the right combination of cost effective actions that would enable reaching GES for all the different components of the marine environment. The challenge is to understand and model the effects of multiple pressures so that policy makers can select and implement an effective set of measures. Therefore, the understanding of the trade-offs between various actions and their effect on the marine environment is crucial.
Together with other partners in the STAGES research project, ICES recently took the first steps towards laying a potential framework for marine CIAs. 'Towards management of multiple stressors in the context of the Marine Strategy Framework Directive: a Baltic Sea pilot study', examined approaches that considered potential trade-offs for MSFD PoMs with regard to measures regarding either fishing, eutrophication, or both.
This pilot project focussed on the multiple pressures associated with fishing and eutrophication because of their prominence in some European waters and they provide a range of pressures for inclusion in a cumulative impact assessment. Fortunately, scientific knowledge on the ecosystem effects of fishing and eutrophication is also the most developed.
Using a combination of pressure reductions (0%, 30 % and 60%), the study tested complementary approaches to model and assess the impacts on the ecosystem.
One approach, based on the methodologies of Baltic Sea Pressure and Impact Index and applying the HELCOM Biodiversity Assessment Tool , produced a spatial visualization of GES and cumulative pressures and effects on the ecosystem.
Another approach applied a Bayesian network model, where expert judgment was used to evaluate the likely responses of the ecosystem, taking into account the associated uncertainties.
Finally, the third approach applied an existing Baltic Sea food web model (the BaltProWeb model) to predict changes in cod biomass under the reduction scenarios of nutrient inputs and fishing pressures.
Combining results from the three approaches suggest that reductions in either fisheries or eutrophication pressures would improve the environmental status of the Baltic Sea but that without further management action on eutrophication, actions on fisheries management would not fully realise the benefits from reduced fishing pressure.
With all the complex interactions that take place within the marine ecosystem, there is no single tool that can provide answers to the questions, such as those asked within this case study. However, gathering knowledge from multiple sources, as demonstrated in this study, can be used to provide advice to inform policy decisions.
The study points out that it is increasingly important to integrate knowledge from multiple sources into advice and the workshop participants expressed the hope that this pilot study is used in the further development of science-based advice (for the MSFD and the HELCOM Baltic Sea Action Plan) and tools to select management measures.
The report from the study, Towards management of multiple stressors in the context of the Marine Strategy Framework Directive: a Baltic Sea pilot study is now available as part of the STAGES MSFD Decision Resources e-Package.
To attain GES and the continued delivery of ecosystem services, cumulative effects of human pressures must be understood and managed. The workshop organizers will continue the discussion in a theme session at ICES ASC 2015. Marine environmental scientists and CIA practitioners are invited to discuss methodologies that assess potential cumulative impacts, concepts of additive, synergistic, antagonistic and cumulative impacts, case studies, and evidence-based management of multiple pressures.
STAGES, Science and Technology Advancing Governance on Good Environmental Status was an EC-funded research project connecting science to policy to help achieve Good Environmental Status (GES) in marine waters.
ICES role in the STAGES project was to ensure that relevant knowledge, already generated through marine environment research at both EU and national level, was identified, analysed, and made available in a format that was easily accessible and usable by policy makers and the wider MSFD stakeholder community. In addition, ICES identified further research needed to improve the scientific underpinning for the implementation of the MSFD.
More information can be found on STAGES website.
Eutrophication in the Baltic Sea, July 25, 2014. Photo: EOS-MODIS, NASA. This ICES/STAGES pilot study looked at what effects might result from reducing cumulative human induced pressures, namely eutrophication and fishing.