Cumulative effects assessment Henn Ojaveer, Estonia Vanessa Stelzenmüller, Germany Marta Coll, Spain

Definition Cumulative effect is termed as aggregated, collective, accruing, and (or) combined changes to the environment that result from a combination of past, present and future human activities and natural processes

Cumulative effect can be: Additive: a combined effect produced by the action of two or more agents, being equal to the sum of their separate effects, i.e. the total impact is the sum of its parts; Antagonistic: a combined effect produced by the action of two or more agents, being less than the sum of their separate effects; Multiplicative: multiple activities have a total effect that is multiplicative and therefore larger than their sums; Mitigative: some activities mitigate the effects of others and thus the total effect of multiple activities is lower than their sum; Synergistic: the interaction of two or more agents or actions so that their combined impact is greater than the sum of their individual impacts. Also, other impacts are included if their manners produce new impacts

Korpinen, Andersen 2016

Major limitations currently: Pressure data quality (quantification, spatio-temporal precision) Pressure-impact relationship (usually linear) Impacts validation Previous impacts (ecosystem already modified!) Additive model Some basic assumptions may bias assessment results! Korpinen, Andersen 2016

EU COST Action

MarCons about CEAs: Develop/identify a comprehensive framework Develop new science-policy links and feedbacks Develop/improve new scientific tools RISK-BASED APPROACH (linked to policy, reduces complexity, increases transparency, handles uncertainty, incorporates science) Stelzenmüller et al. 2018

Risk management process Stelzenmüller et al. 2018

Stelzenmüller et al. 2018

Summary We have to find a solution to “take-up” routine CEA in the context of MSP/or MSFD implementation processes. Stelzenmüller et al. 2018 was the starting point of thinking on how to “operationalize” the science-policy interface in relation to CEAs. The proposed risk approach builds on the policy requirements and related management objectives – so it tries to help to focus on the “components under threat due to combined pressures”. EU COST MarCons activities will move forward from the CEA mapping activities to tailored CEA products.

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