scientific chapter |
Cabaitan PC, Quimpo TJR, Dumalagan Jr. EE, Munar J, Calleja MAC, Olavides RDD, Go K, Albelda R, Cabactulan D, Tinacba EJC, Doctor MAA, Villanoy CL, Siringan FP
The Philippines is situated within the Coral Triangle marine biodiversity hotspot and supports highly diverse coral reef communities. However, Philippine reefs are exposed to many natural and anthropogenic disturbances. Consequently, mesophotic coral ecosystems (MCEs) have drawn increasing interest because of their potential significance as refugia for many reef species. MCEs in the Philippines occur in a variety of settings, reflecting the wide diversity of reef habitats within the archipelago. MCEs remain poorly studied compared to shallow reefs, but preliminary investigations show that MCE sites support diverse ecological communities. Here, we describe the physical features, biodiversity, and current condition of three MCE sites in the Philippines that occur in different environmental settings: surge exposed fringing reefs at Patnanungan, turbid fringing reefs at Abra de Ilog, and the oceanic atolls of Apo Reef. Patnanungan is dominated by rubble fields with high macroalgae cover, an indication of destructive fishing and overexploitation of herbivorous fishes and invertebrates. Abra de Ilog is exposed to turbid waters due to two nearby rivers, and as a result, hard corals are not found below 30 m. Apo Reef, an oceanic atoll located within a marine park, supported higher abundance and diversity of benthic and mobile megafauna at mesophotic depths than the other two sites. MCEs are probably common throughout the Philippines, and future research should investigate additional sites, include long-term monitoring of factors driving spatial and temporal patterns of biodiversity, and investigate the potential importance of Philippine MCEs as refugia.