Linking integrity of coastal habitats and fisheries yield in the Mantalip Reef System

Abstract

Reef systems comprised of adjacent mangroves, seagrass beds and coral reefs are common in the tropics. These multi-habitat systems exhibit enhanced productivity of coastal areas compared to single habitat systems. Yet in the Philippines, only few studies had been done demonstrating the importance of inter-habitat interactions in enhancing coastal productivity. This study investigates (1) the fisheries connectivity among component habitats of the Mantalip Reef System (Negros Oriental, Philippines), and (2) its implications to refining the current fisheries management scheme. As indicator of connectivity proxy, we inferred inter-habitat movement of fish through size-frequency distributions of families, focusing on species present in two or more of the habitats (mangroves, seagrass beds and coral reef). Fisheries yield was also determined through monitoring of catch landings. Although only 13.97% of all reef fishes were found to utilize multiple habitats, these included large-sized and commercially important taxa that comprised 52.68% of the demersal, reef-associated (vis-à-vis pelagic, open ocean) fish catch biomass. Juveniles were more abundant in the near-shore habitats (mangroves and seagrass), while more mature stages were more abundant in subtidal areas (seagrasses and reefs), demonstrating the critical importance of a multi-system continuum in the juvenile-adult life stages of these taxa. The estimated annual fisheries yield attributable to mangroves (18.88–37.36 mt) and seagrass beds (3.37 mt) increased substantially the total productivity of coral reefs in the system. Altogether, this study underlines the importance of maintaining the integrity and connectivity of adjacent coastal habitats to sustain fisheries demand in the Mantalip Reef System. Results of the study have guided the review of the municipal fisheries ordinance and MPA management plans. Information campaigns in the LGU have also been geared towards emphasizing the importance of their coastal habitats as an interconnected unit.