Biogeography, diversity and conservation of freshwater fishes in the Philippines, a tropical fringing archipelago

Within South East Asia, the Philippines can be regarded as a country with less studied freshwater ichthyofauna. Being a fringing archipelago with dynamic topography and geological history, the Philippines is an interesting place to study freshwater biogeography. In this study, published species list were analyzed to determine the biogeography of native freshwater fishes in the Philippines. About 100 fish species living in Philippine inland waters are native and solely freshwater or has very low saltwater tolerance. Most of these fishes belong to cyprinids (Cyprinidae), Gobies (Gobiidae) and halfbeaks (Hemiramphidae), with having different distributional patterns along the archipelago. The southern (Mindanao) and western (Palawan-Mindoro) biogeographic provinces are unique for its endemic cyprinids, while the north (Luzon) and central (Panay-Negros and Samar-Leyte) islands are home to endemic rice fish, gobies and halfbeaks. Both environmental and geologic factors have effects on the biogeographical patterns, with differing degree depending on the species group. Vulnerability of Philippine inland waters is high due to elevated deforestation, introduction of exotic species and anthropogenic climate change. Conservation of these habitats is vital for the survival of the native freshwater fishes. Further field sampling are necessary to understand and determine the present status and the total species diversity.