Phytoplankton Community Structure and Environmental Variables as Indicators of Organic Pollution in Padma River, Bangladesh

Environmental assessment of Padma River through the bio-monitoring of environmental parameters, phytoplankton community structure and their interaction was studied. Total 11 environmental parameters and 54 genera of phytoplankton were investigated for two seasons (summer and winter) at two sites situated about 25 km apart from each other (urban = 24o 27´ 34.79" N, 88o 20´ 09.54" E and rural= 24o 27´ 34.79" N, 88o 20´ 09.54" E). Pooled data of the two studied seasons were used for analysis. Environmental parameters of the urban site were found significantly (P<0.05) different from the rural site. Analysis of similarity (ANOSIM) revealed dissimilarity in phytoplankton community pattern between the sites (R=0.6929; P=0.0001), whereas SIMPER analysis indicated Surirella (3.57%), Zygnema (3.55%), Rhizosolenia (3.51%) and Chroococcus (3.04%) as the most important contributors that were responsible for dissimilarity. According to BIO-ENV analysis, PO4-P identified as the key parameter (ρw=0.643) that influenced the structure of the phytoplankton community. The phytoplankton genera influenced mostly by PO4-P were Ankistrodesmus, Chlorella, Pediastrum, Scenedesmus, Fragillaria, Phormidium, Euglena, Phacus, Synedra, Anabaena, Microcystis, Nitzschia, Cyclotella, Cymbella and Oscillatoria. Higher abundance of pollution tolerant genera and PO4-P concentration reflect organic pollution at the urban site of Padma River.