Phytoplankton Community Structure in the Coastal Waters of Barangay Bawing, General Santos City

The phytoplankton community plays a vital role in the marine environment and can serve as an indicator of water quality. This study focused on identification and determined the composition and diversity of phytoplankton in the coastal waters of Barangay Bawing. A total of 31 genera had been recorded from the four classes of phytoplankton namely Cyanophyceae, Bacillariophyceae, Dictyophyceae, and Dinophyceae with Cyanophyceae being the most abundant. The genus Trichodesmium, a nitrogen-fixing Cyanophyceae, exhibited the highest mean density of 160,258 cell/m³ with a relative abundance (RA) of 55.34% which due to the presence of nutrients loaded
by land use and anthropogenic activities in the coastal area. The genus is then followed by Leptocylindrus, Pseudo-nitzschia, Chaetoceros, and Thalassionema with an RA of 16.56% (47,967 cell/m³), 8.42% (24.377 cell/ m ^ 3) 5.59% (16,199 cell/ m ^ 3) and 3.94%(11,323 cell/ m ^ 3) respectively. All other phytoplankton species were poorly represented in the phytoplankton samples. Salinity, DO, Conductivity, and TDS have significant correlation to the phytoplankton community structure in the area and were within the tolerable limits for marine waters set by the water quality guidelines of DAO-2016. Thus, supported the growth and diversity of phytoplankton community. Moreover, S3 has the highest species richness (D = 0.3714) yet low in diversity (H' = 1.041) On the contrary, S2 has more diverse species (H' = 0.999) and relatively high in species richness (D = 0.3954) These variations suggest the influence of local environmental factors, such as nutrient availability and temperature on the phytoplankton community structure. Overall, this study provides valuable insights into the phytoplankton community in Barangay Bawing and contributes to the existing data on phytoplankton populations in General Santos City.The findings can be utilized by water quality managers for monitoring and managing the marine environment. Further analysis and investigation are recommended to understand the underlying factors driving the observed variations in the phytoplankton community.