Natural capital and environmental flows assessment in marine protected areas: The case study of Liguria region (NW Mediterranean Sea)

Description

A methodology based on emergy analysis for the calculation of the biophysical value of the stocked biomass (natural capital) was applied to the Marine Protected Areas (MPAs) of Portofino (PF) and Cinque Terre (CT). The resources exploited, on a yearly base, to maintain the natural capital itself alive (environmental flows) were accounted too. Emergy analysis is an accounting method useful to identify and convert in a single unit of measure all resources feeding a system. This allows the implementation of a system overall assessment and then the conversion of the obtained value in money terms. The studied MPAs are located in the northwestern part of Italy, are both tourism oriented and subdivided in zones with different protection degree. The habitats occupying both the MPAs bottoms have been identified together with the biomass stored on their surface, identifying units named FBHA (fishes and benthos habitat assemblage). The calculation of biomass stocked in the benthic organisms and in the fishes associated to each FBHA represents the basis for the assessment of MPA natural capital value and of environmental flows. From these values, the trophic network of each habitat was modeled allowing calculating the inputs to emergy analysis. The value of PF natural capital, expressed as resources employed through space and time to store the existing biomass, is equal to over 10 million Euros while the CT natural capital amounts to over 30 million. The high value habitats, where biomass is concentrated and stored, represent hot spots that are restricted in a limited surface and that can be maintained only if the resources they need are provided by adjacent lower value habitats. Through the applied methodology, a balance is performed to understand if an MPA is self-sufficient or dependent on external areas. Therefore, if an MPA is correctly planned, as CT is, the wider low value areas are able to provide resources to the deficit FBHAs and even to export resources to other systems. In this case, the MPA lies in a surplus condition. On the contrary, the MPA is not able to maintain itself and depends on external systems not subjected to protection and then potentially posed at risk. If information about natural capital, flows and balance is synthesized in a Geographical Information System, it represents an effective tool to MPAs managers to measure the efficacy of protection established.

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