Valuation of ecosystem services in marine protected areas: A comprehensive review of methods and needed developments

Effectively managing Marine Protected Areas (MPAs) requires recognising and understanding the fundamental services offered by marine ecosystems and the socio-economic consequences that their changes will have. A systematic literature review was performed to generate a first in-detail screening and assessment of monetary and non-monetary methods for the valuation of ecosystem services (ES) and their application in MPAs and MPA networks. A total of 100 peer-reviewed papers on ES valuation within MPAs and MPA networks were identified and analysed. Valuation methods can be classified into nine monetary and seven non-monetary methodologies. There is a predominant use of monetary valuation methodologies, especially stated preference methods. However, combining monetary with non-monetary valuation approaches can provide deeper insights into the underlying reasons for assigning values to ES and offer enhanced opportunities to capture the value of services that may be challenging to express solely in monetary terms. Besides, the review underscores the gaps in assessment methodologies, particularly in addressing supporting and regulating ES, as well as non-use and option values related to MPAs, underscoring the need for innovative approaches to overcome challenges in capturing these essential components of marine ecosystems.