• Annie Sinha
• Sunil Kumar Choudhary

The phytoplankton constitute a major segment of the primary producers and thus the phytoplankton primary production in the fresh water ecosystems acquire immense importance. The photosynthetic fixation of carbon dioxide and its quantitative measurements is considered a vital index of the productive potential of any aquatic system represented by the weight of organic matters. Present study represents the seasonal variations in productivity of main channel and side channel of River Ganga at Bhagalpur. The light and dark bottle method (Gaarder and Gran, 1927) was used to measure primary production. Gross Primary Production (GPP), Net Primary Production (NPP), Community respiration, respiration as percent and P/R ratio were studied at four sampling sites during pre-monsoon and post-monsoon seasons of 2015 and 2016. Maximum and minimum value of GPP was recorded during pre-monsoon and post-monsoon season at site II. The site wise analysis of NPP indicated maximum (4.05 g C/m3/d) productivity in the pre-monsoon and minimum (0.08 g C/m3/d) in post-monsoon season at side-channel i.e., Khirni Ghat. A maximum (2.25 g C/m3/d) value of community respiration was observed at Hanuman Ghat (side channel) during post-monsoon (2015) and pre-monsoon (2016) and a minimum (0.27 g C/m3/d) value during pre- and post-monsoon season at mixing zone. Maximum (0.83) value of P/R ratio was observed during post-monsoon and minimum (0.002) during pre-monsoon season. Overall on the basis of observation it may be concluded that whole stretch of the sampling sites are eutrophic in nature.

River Ganga, Main and Side channels, Gross primary productivity (GPP), Net primary productivity (NPP)

"Studies on Seasonal Variations in Primary Production of Main Channel and Side Channel of River Ganga at Bhagalpur", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.6, Issue 5, page no.619-624, May-2019, Available :http://www.jetir.org/papers/JETIR1905986.pdf

"Studies on Seasonal Variations in Primary Production of Main Channel and Side Channel of River Ganga at Bhagalpur", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.6, Issue 5, page no. pp619-624, May-2019, Available at : http://www.jetir.org/papers/JETIR1905986.pdf