Phytoplankton Population Dynamics in Relation to Environmental Variables at Paradip Port, East Coast of India

Paradip port is one of the biggest and busiest harbors in eastern India. The cargo handling and material transport in the harbor release spillage materials into the marine environment, which causes pollution to the aquatic ecosystem. The present study elucidates the spatial-seasonal variation of phytoplankton and physicochemical variables (temperature, pH, salinity, turbidity, dissolved oxygen, biochemical oxygen demand, nitrite, nitrate, ammonia, and phosphate) from January 2017 to December 2018 at Paradip harbor water. Physicochemical parameters such as temperature, salinity, turbidity, nitrite, nitrate, and ammonia showed seasonal variation due to evaporation and rainwater influx. A significant positive correlation was observed among all the nitrogenous nutrients and also with temperature and salinity. Around 41species of phytoplankton belonging to classes Coscinodiscophyceae, Bacillariophyceae, Fragilariophyceae, Dinophyceae, Noctilucophyceae and Cyanophyceae were detected. Coscinodiscophyceae was the dominant class, followed by Dinophyceae and Bacillariophyceae. Canonical correspondence analysis revealed that high turbidity in the monsoon season flourishes the growth of Biddulphia sp., Protoperidinium sp., Cyclotella sp., and Gyrosigma sp. The nutrient-rich system in pre-and post-monsoon enriches Coscinodicus sp., Chaetoceros sp., Rhizosolenia sp., and Bacillaria sp. Elevated temperature supports Triceratium sp. growth, and salinity helps Dinophysis, Ceratium, Pyrophacus, and Prorocentrum species growth. The highest phytoplankton population was observed in the winter season, followed by the monsoon, pre-monsoon, and post-monsoon. Shannon-Wiener's (H') diversity index of the phytoplankton population ranged from1.5417-2.2284, evenness index (J') ranged from0.7833-0.9720, and species richness index (d) ranged from 5.3245-10.8495. The water quality index and diversity indices showed that the harbor system is under moderate stress.