Exceptional reefs of Palawan: Anthropogenic extinction, reef refuge areas under climate change, and priority species for conservation

• Main Author: Luzon, Katrina S.
• Format: text
• Language: English
• Published: Animo Repository 2022
• Subjects: Scleractinia > Philippines > Palawan; Endangered species > Philippines > Palawan; Biology
• Online Access: https://animorepository.dlsu.edu.ph/etdd_bio/5
• Institution: De La Salle University

The National Assessment of Coral Reef Environments (NACRE) Program reported that one-third of the reefs in the Philippines declined in the past decade. As human activities and climate change effects intensify, there is still a lack of systematic prioritization of species and reef areas that should be protected to ensure the preservation of coral diversity in the country, particularly in Palawan province which has its richest reefs. The objectives of this study are 1) to identify coral species that are evolutionarily distinct and vulnerable to anthropogenic impacts and climate change that should be prioritized for protection; and 2) to identify reef areas that are possible refuges under the worst climate scenario. This study made use of species richness, phylogenetic diversity, and index of rarity to determine priority species and reef areas in Palawan that are vulnerable to anthropogenic impacts. This study proposes 30 evolutionarily distinct and locally endangered species and 88 globally rare species. These species include the eight IUCN endangered and globally rare species (Cantharellus noumeae, Alveopora minuta, Alveopora excelsa, Porites ornata, Hydnophora bonsai, Pectinia maxima, Anacropora spinosa, and Lobophyllia serrata). El Nido was found to have the highest species richness and phylogenetic diversity, while the Calamianes has the highest index of rarity in the whole of Palawan. Ecological Niche Model (ENM), a machine learning tool, was used to project future potential refugia in Palawan under the stabilized emissions scenario of RCP 4.5 and the high emissions scenario of RCP 8.5. Ecological niche models reveal three range shift patterns: habitat loss, west and east coast shift, and the deeper range shift. The average habitat reduction in Palawan across 75 species is 4% (SD ±17%) in the RCP 8.5 scenario and 3% (SD ±14%) in the RCP 4.5 scenario. At the national level, models trained in Type 1 coral communities of the country exhibit a habitat loss of > 36% under RCP 4.5 and >45% under RCP 8.5. On the other hand, models trained in Type 1 coral communities of Palawan showed an increase of 40% under RCP 4.5 and 87% under RCP 8.5. A Type 1 coral community is one out of seven coral community types in the Philippines. Type 1 coral communities are dominated by Acropora and massive Porites corals on upper reef slopes that face the southwest monsoon. The models show that well-developed coral reefs are potential refuge areas and should be prioritized for protection. Other potential refuge reefs include upwelling sites in the Philippines and the atolls of Cagayancillo and Tubbataha. Palawan reefs and other Type 1 coral communities of the country like those in the Bicol Shelf, Bohol, Visayan Sea, and Tawi-Tawi and the shallow reefs of the Sunda Shelf, which includes Sabah, Malaysia and the Riau Islands, Bangka-Belitung, and North and West Sumatra in Indonesia were found to be the best conditioned and well-adapted reef areas for the worst-case high emissions scenario of future climate.