Exploring Seagrass Diversity and Associated Flora and Fauna in the Coastal Waters of Northwestern Dumanquilas Bay

Abstract

The coastal waters of northwestern Dumanquilas Bay, specifically in Vincenzo Sagun, Zamboanga del Sur, harbor ecologically important seagrass meadows that serve as critical habitats for a wide variety of marine flora and fauna. However, these ecosystems are increasingly threatened by human activities and climate change. Despite their importance, scientific information on the composition and distribution of seagrass species and associated biota in the area remains limited, creating challenges for effective conservation. This study examined three sampling stations using a descriptive-quantitative approach and the transect-quadrat method. Each station had a 5×100-meter belt transect surveyed during low tide. Species were identified, photographed, and classified, and biodiversity indices—including the Shannon-Wiener Index, Simpson’s Diversity Index, Pielou’s Evenness Index, and ANOVA—were used to assess abundance and diversity. Four seagrass species were recorded: Halodule uninervis, Thalassia hemprichii, Enhalus acoroides, and Halodule pinifolia. Thirteen fauna and six flora species were also documented, such as Turris babylonia, Astropecten polyacanthus, and Caulerpa racemosa. T. hemprichii was the most dominant species. Station 2 had the highest seagrass and fauna richness, while Station 3 showed the highest flora diversity. Overall biodiversity was low, and ANOVA results indicated no significant differences in species abundance across stations. The findings highlight the influence of substrate, light, and environmental factors on species distribution. The study recommends wider research coverage, inclusion of water quality data, conservation of rare species, and stronger community-based management. Long-term monitoring and reinforcing marine protected areas are crucial for preserving seagrass ecosystems and their biodiversity.