Phytoplankton communities in Palien basin, Trang province, Southern Woraporn Tarangkoon1*, Wachirapan Kongnuan2 and Nikom Onsri1 1Department of Marine Science, Faculty of Science and Fisheries Technology, Rajamangala University of Technology , Trang 92150, Thailand 2Oyster Breeding Research Unit, Department of Marine Science, Faculty of Science and Fisheries Technology, Rajamangala University of Technology Srivijaya, Trang 92150, Thailand Phytoplankton communities in Palien basin, Trang province, Thailand, were investigated at four stations during spring tides and neap tides from October 2017 to December 2017. At the surface and mid water depth, ten liters of water were sampled and concentrated with a 21-micron sized mesh net and then preserved with 2% final concentration neutral formalin. Three replicate samples of phytoplankton were collected at each depth and each station. The phytoplankton was identified to genus level and enumerated. Total density, species diversity, richness and evenness of phytoplankton were calculated. Environmental parameters were investigated in situ, including salinity, temperature, pH and water depth. A total of 58 genera of phytoplankton were identified during the study period. Bacillariophyceae was the most dominant group, followed by, Dinophyceae, Euglenophyceae, Chrysophyceae, Cyanophyceae and Chlorophyceae. Total phytoplankton densities varied from 341±43 cell L-1 to 32,820±6,214 cell L-1. Highest diversity and species richness of phytoplankton were found at station 1 during the spring tide while the highest evenness was recorded at station 4 during the neap tide.There were significant differences in total density of phytoplankton (P<0.05) between spring -neap tides, between stations and between sampling depths. Further studies in other seasons are needed to clarify the seasonal variation of the phytoplankton communities in Palien basin in Trang province.

Keywords: Phytoplankton, Coastal water, Trang Province, Thailand *Presenter: E-mail: [email protected]

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