Community structure of phytoplanktons community in two different areas along Getalsud Dam of Jharkhand state

सार

Blooms including red-tides caused by phytoplankton are of significant value in the aquatic environment as they affect marine economy. Hence, an analysis of phytoplankton becomes essential in any study concerning hydrobiological investigations. Present study focusses attention on a thorough investigation of phytoplankton with reference to their species makeup, percentage contribution, population density and community structure. All these are calculated by prescribed formulas. The present study areas (stations 1 and 2) form a typical dumping yard system. Both the stations are present in the Jharkhand state along Getalsud dam basin area. The first collection site was fixed near the northern bank of the dam which was 1 km west of the residential area. The second selected site was fixed near the southern bank of the dam which was 2 km east of the small industrial area. The river water is extensively utilized for agriculture, fisheries, irrigation and navigation purpose. For two years, samples were taken from the surface waters of the research sites once a month, from October 2022 to September 2023. For convenience's sake and easy interpretation, a calendar year was divided into four seasons: postmonsoon (January to March), summer (April to June), premonsoon (July to September) and monsoon (October to December). These samples were utilised for qualitative examination after being stored in 5% neutralised formalin. Regarding the quantitative analysis of phytoplankton, the settling technique was used. Plankton numerical analysis was performed using Utermonl's inverteo-plankton microscope. Analysis of phytoplankton of stations 1 and 2 showed the presence of 187 species. Diatoms were the dominant group contributing 71.12% followed by greens and blue greens contributing 9.63% and 8.56% respectively. Dinoflagellates and others contributed only 3.74%. Each group's percentage contribution towards phytoplankton composition in the increasing order was as follows:
Others < Dinoflagellates < Blue-greens < Greens < Diatoms.