Economic assessment of ecosystem services: Monetary value of seagrass meadows for coastal fisheries

Abstract

Estimation of the economic value of ecosystem services is particularly incipient in the marine realm, where numerous services still need to be evaluated. Seagrasses deliver essential services to humans. In this paper, we determined the economic value of Cymodocea nodosa seagrass meadows for local fisheries at the oceanic island of Gran Canaria (eastern Atlantic). Large-sized fishes, which constitute the fishable fraction, were seasonally sampled through 2011 by means of visual censuses at 12 seagrass-dominated sites. The total fish biomass was 907.6 kg (894.55 kg of commercially-targeted fishes). By using standard market prices, we estimated that the monetary value of this biomass averaged 866 € ha−1; at the island-scale, this value adds up to 606 239 €, when considering the area covered by C. nodosa. Small-sized fishes (mostly juveniles that replenish fisheries) were also seasonally sampled, through a seine net, at the same 12 seagrass-dominated sites. Eight nearshore fish species with commercial interest used seagrass meadows as ‘nursery grounds’. Estimates of secondary production revealed that this fish production monetarily averaged 95.75 € ha−1 y−1 when considering standard market prices; this value adds up to 67 030.30 € y−1 at the island-scale, when considering the area covered by C. nodosa. This study provides complementary assessments of the key economic contribution of seagrass meadows for coastal fisheries as both ‘fishing’ and ‘nursery’ grounds. This is a way to promote the social perception of the key role that seagrasses play on the coast and, therefore, the necessity of incorporating seagrasses into conservation legislative frameworks.