Diatom Assemblage from Surface Sediments of Lower Assam Floodplain, Northeast India

Diatoms and environmental conditions were characterized from 10 sampling points in two major wetlands namely Deepor and Kumuri beel in lower Assam floodplain. A total of 38 taxa identified, viz., planktonic (Melosira granulata, Tabellaria flocculosa, Diploneis subovalis, Stauroneis anceps, Nitzchia palea, Fragilaria virescens, etc.), epiphytic (Eunotia pectinalis, Navicula hasta, Achnanthes brevipes, Pinnularia borealis, etc.), epissamic (Surirella elegans, Gomphonema lanceolatum, etc.), epipelic (Rhopalodia gibberula, Synedra ulna, etc.) and endozoic group (Cymbella turgida, Pinnularia interrupta, etc.) is suggesting that the wetland surface sediment diatom assemblage is heterogeneous and that hydrologic gradients may be an important structuring force. Our preliminary result from northeastern region could be potential to be a useful tool in assessing wetland environmental conditions, however, the shallow nature and complex hydrology of these systems require careful and precise sampling design for adequate characterization of diatom assemblages. Besides the diatom, other algal assemblages are also equally important to play a key role in wetland function and can be valuable indicators of biological integrity and ecological condition.