Species Composition, Abundance, Distribution and Diversity of Seagrass at Provinces of Sulu and Basilan, Philippines

Seagrass plays a vital role in coastal ecosystems by supporting biodiversity, fisheries, and local economies. However, security concerns have limited research on seagrass in Sulu and Basilan, Philippines. This study assessed the seagrass status across 12 coastal municipalities in the provinces of Sulu and Basilan, Philippines, using the line transect-quadrat method, covering 580 transects and 5,600 plots. Six seagrass species from the family Cymodoceaceae (Cymodocea rotundata, Halodule uninervis and Syringodium isoetifolium) and the family Hydrocharitaceae (Enhalus acoroides, Halophila ovalis and Thalassia hemprichii) were identified. Seagrass cover was fair in Omar (41.83%), Pangutaran (33.18%), Tabuan Lasa (31.96%), Luuk (29.73%), and Banguingui (28.89%), while it was poor in Sumisip (21.75%), Hadji Muhtamad (18.78%), Hadji Panglima Tahil (18.43%), Patikul (15.98%), Lantawan (15.10%), Maluso (14.25%) and Panamao (9.60%). T. hemprichii (45.97%) and C. rotundata (35.44%) dominated, collectively comprising 81% of the total cover. E. acoroides contributed 18.76%, while the remaining species had low coverage (7.85%–11.74%). Diversity indices indicated low diversity with an overall Shannon-Weiner diversity index (H = 1.3367), Pielou’s evenness (e = 0.13566), and Margalef’s index (Sm = 0.4807). Associated flora included Chlorophyta, Rhodophyta, and Phaeophyta, while fauna was dominated by Asteroidea, Anthozoa, Gastropoda, and Echinodea. Thus, the degraded seagrass beds in the eastern part of the Sulu Sea highlight the need for immediate conservation efforts, monitoring, and management strategies. Protecting these habitats is crucial for biodiversity and sustaining local livelihoods dependent on the Sulu Sea’s resources.