Temporal and spatial dynamics of phytoplankton in the Palian river, Trang province, southern west coast of Thailand.

A study on species compositions, distribution of phytoplankton and water quality in the Palian river, Trang province was carried out. The results showed that a total of 82 phytoplankton species were which diatom was dominant in both season. The total cell density of 20,504 unit/L was found in summer, highest in Palian estuary. The dominant species found in the summer were Cyclotella sp., Thalassiosira sp., Chaetoceros diversus, Chaetoceros lorenzianus, Bellerochea horologicalis, Thalassionema frauenfeldii, Thalassionema nitzschioides. And the total cell density of 20,138 unit/L was found in rainy season highest in Palian estuary. The dominant species found in the rainy season were Oscillatoria thiebautii, Amphora sp., Pleurosigma sp. and Bacillaria paxillifer. The concentrations of ammonia-nitrogen, nitrate-nitrogen and orthophosphate-phosphorus were higher in summer season (0.056±0.014, 0.081±0.045 and 0.082±0.011 mg/L, respectively). The diversity index, evenness index and richness index were in the range of 2.460-3.720, 0.344-0.506, and 1.279-2.135, respectively. The results can be used to evaluate primary production, including the production of aquatic animals in water sources which is used as an index to measure the abundance of the water source ecosystem in the Palian river, Trang province.