HYDERABAD: A joint study, led by researchers from the University of Hyderabad (UoH) and other national and international organisations, has found that riverine discharge from the Godavari intensifies the oxygen-depleted zones (ODZ) or dead zones near its mouth in the Bay of Bengal.
Apart from the UoH, scientists from the CSIR-NIO in Visakhapatnam and King Abdullah University of Science and Technology in Saudi Arabia also took part in the research published in the Frontiers in Marine Science journal. It highlighted that Godavari could have significant impact on the intensification of ODZ, besides major rivers like the Ganga and Brahmaputra.
Researchers analysed the river discharge data from the Godavari at the Dowlaiswaram barrage, World Ocean Atlas 2018 data and high-resolution biogeochemistry recorded Array for Real-Time Geostrophic Oceanography (ARGO) buoys in the Bay of Bengal off Godavari river mouth.
The study found that during the monsoon season, when the Godavari experiences peak discharge, large amounts of organic matter from dead trees, plants or soil are carried into the Bay of Bengal. In addition to this, river water also carries huge amounts of nutrients to the coast that enhance phytoplankton production.
A mentor to the lead author, Prof K Ashok, told TNIE, “This is the first time that the effect of Godavari on the Bay of Bengal has been studied. Fish cannot thrive in ODZs. The study found that Godavari flow could also be contributing to a decrease in the oxygen levels in some zones in the Bay of Bengal, affecting fishing activity.
Since Godavari is rainfed, any decrease in monsoonal rainfall due to interannual climate drivers, will decrease river run-off, which, in turn, may improve the oxygen levels in the ODZ and thus fishery catch.