Reef Community Structure of Darvel Bay (Northeastern Borneo): A Current Assessment of Coral Condition, Diversity and Disease Prevalence

Darvel Bay, situated on the northern edge of the Coral Triangle, is characterized by high coral species richness and diverse reef habitats. The bay primarily consists of fringing reefs along the mainland and surrounding islands, with water conditions ranging from turbid in sheltered inner reefs to crystal-clear waters at offshore sites. In line with the gazettement plan proposed by the Sabah State Government to establish a Marine Protected Area in Darvel Bay, twelve reef sites were surveyed to build upon past research and provide updated data on coral conditions, including their diversity, abundance patterns and disease prevalence. Surveys were conducted at a depth of 10 m using the Coral Video Transect (CVT) method and the video footage was analysed using Coral Point Count with Microsoft Excel extension (CPCe) software. The findings indicate that reefs in Darvel Bay had a mean live coral cover of 52.4% ± 5.5, with offshore reefs exposed to minimal human disturbance generally exhibiting “Good” conditions and higher coral diversity than nearshore sites. The reef assemblages comprised 256 scleractinian coral species from 70 genera and 15 families. When combined with existing species checklists from the east coast of Sabah, a total of 415 scleractinian species from 81 genera and 18 families are now recognized in the region, including 33 rare, 130 endangered and 24 vulnerable species. The data presented here also revealed 81 genera of hard and soft corals, with Porites , Acropora and Fungia being the most dominant, likely due to their adaptability to varying reef conditions. Nonetheless, intense urbanization and extensive land-use changes along the mainland may have negatively influenced coral communities at inshore reefs and further contributed to the higher prevalence of coral diseases and compromised health, including skeletal eroding band (SEB), ulcerative white spot (UWS), sediment necrosis (SN) and skeletal damage (SKD). Therefore, the implementation of gazettement plan, supported by proper regulations and long-term sustainability policies, is vital to help in achieving a balance between reef protection and the well-being of coastal communities in Darvel Bay.