Challenges in using valuation in ecosystem-based management in a marine context: the case of UK Marine Protected Area designation - Ocean Sustainability in the 21st Century - page 252

7.4.1 Case study valuation: limitations
The MCZ case study has been selected here to showcase a valuation application that was
successful in the sense that it contributed significantly to the evidence base supporting the
Marine and Coastal Access Act by producing tangible and credible results. But in presenting
the methodology and results it is apparent that there are limitations that should be borne in
mind .
The MCZ studies (Hussain et al ., 2010 ; ABPMer, 2007 ) produced a benefit-cost ratio
of at least seven, based on values for only seven of the eleven services, and the ecosystem
service typology excluded non-use (existence) values. This is a strong policy-relevant out-
come, but equally points to a potential limitation in commoditizing services in monetary
terms, i.e. omitted benefits. If the benefit streams that can be monetized exceed costs (as
was the case in the MCZ study) then this is a sufficient condition for economic efficiency.
But it is not a necessary condition in that there are omitted benefit streams. In the aggreg-
ate service values used ( Table 7.2 ), there was systemic undervaluation in some cases, e.g.
the estimate for gas and climate regulation being based solely on the carbon sequestered by
phytoplankton from photosynthesis. There is the potential for any monetized benefit estim-
ate to dominate the policy discourse, even if it is partial and caveats as to qualitative benefits
are stated.
Caution must be applied in overstating the accuracy of any valuation outcomes. For in-
stance, the value for nutrient cycling in a typical hectare of aphotic reef has been estimated
at £830/hectare. The precision of this estimate can be misleading (I provide precise figures
below only so as to allow the reader to follow the methodological steps used). This is par-
ticularly the case because the level of confidence that is appropriate for different estimates
varies between services, with the level of confidence depending on the economic estima-
tion methodology and data sources, and the biophysical science, and the interrelatedness
between the two. The extent of scientific knowledge pertaining to individual habitat/service
combinations was set out in Table 7.3 , revealing significant variability. In terms of the eco-
nomic data, some values are dated and based on relatively poor proxies, as discussed. Fur-