Willsteed, Edward A.Birchenough, Silvana N. R.Gill, Andrew B.Jude, Simon2018-10-312018-10-312018-09-22Willsteed EA, Birchenough SNR, Gill AG, Jude S. Structuring cumulative effects assessments to support regional and local marine management and planning obligations. Marine Policy, Volume 98, December 2018, pp. 23-320308-597Xhttps://doi.org/10.1016/j.marpol.2018.09.006http://dspace.lib.cranfield.ac.uk/handle/1826/13596Cumulative effects assessments are a legal requirement in many jurisdictions and are key to informing marine policy. However, practice does not yet deliver fit-for-purpose assessments relative to sustainable development and environmental protection obligations. The complexity of cumulative effect questions, which are embedded in complex social-ecological systems, makes multiple, methodologically diverse assessments a necessity. Using the expansion of marine renewable energy developments in European Union waters as a case study, this paper explores how social-ecological systems thinking and cumulative effects assessment theory can combine to structure CEAs that better support the management and regulation of maritime activities at regional scales. A general perspective for cumulative effects assessment is proposed to remove ambiguity of intent and to orient assessments towards a common objective. Candidate principles for practice are presented for consideration. These principles are integrated into a stepped assessment approach that seeks to improve cumulative effects assessments of localised activities relative to the information needs of decision-makers implementing the ecosystem approach.enAttribution-NonCommercial-NoDerivatives 4.0 InternationalCumulative effects assessmentCumulative impactMarine managementMarine spatial planningSocial-ecological systemsEcosystem approachArticle