Temporal changes in the community structure of phytoplankton in Panguil Bay, Philippine mangrove estuary

Phytoplankton is an excellent indicator of marine ecosystem change. This study was conducted to investigate the influence of environmental parameters on the temporal assemblage structure of net phytoplankton in Panguil Bay, Philippines, using biodiversity indices and multivariate techniques. A total of 49 species were identified during the 12 months sampling period. Net phytoplankton was documented in decreasing order of abundance: diatoms > dinoflagellates > cyanobacteria. The centric diatom Coscinodiscus wailesii dominated in almost all of the sampling months but outnumbered by the chain-forming Thalassiothrix frauenfeldi, Melosira nummuloides and Thalassionema nitzschioides during the southwest monsoon months (February, August and October). Two discrete clusters formed (species of higher and lower abundance, diversity, evenness and richness). Environmental parameters such as salinity, dissolved oxygen and phosphate exhibited highly significant contribution to the temporal assemblages and composition of phytoplankton in Panguil Bay. The study of phytoplankton community response to these variables is crucial for interpreting hydrological variations in coastal areas.