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ORIGINAL RESEARCH article

Front. Mar. Sci.
Sec. Marine Biogeochemistry
Volume 11 - 2024 | doi: 10.3389/fmars.2024.1419953

Seasonal Intensification of Oxygen Minimum Zone: Linking Godavari River Discharge to Fall Hypoxia in the Bay of Bengal

Provisionally accepted
K S Sreejith K S Sreejith 1*V V. Sarma V V. Sarma 1P Sreenivas P Sreenivas 2F Feba F Feba 2Ibrahim Hoteit Ibrahim Hoteit 3Karumuri Ashok Karumuri Ashok 2*
  • 1 National Institute of Oceanography, Council of Scientific and Industrial Research (CSIR), Dona Paula, India
  • 2 University of Hyderabad, Hyderabad, Andhra Pradesh, India
  • 3 King Abdullah University of Science and Technology, Thuwal, Makkah, Saudi Arabia

The final, formatted version of the article will be published soon.

    This study investigates the biogeochemical impact of the Godavari River Discharge (GRD) on the Bay of Bengal (BoB), focusing on the formation of an intense and shallow Oxygen Minimum Zone (OMZ) off the river mouth during the fall season. Unlike the BoB's typical intermediate-depth OMZ, this subsurface (~40-200 m) phenomenon is attributed to the interplay GRD-driven nutrient enrichment, coastal upwelling, enhanced productivity and subsequent organic matter decomposition. The Biogeochemical-Argo floats and World Ocean Atlas 2018 data revealed a clear shoaling and intensification of the OMZ in the fall season. Further, a comparative analysis at two geographically distinct locations highlighted the pivotal role of GRD. The location directly influenced by GRD exhibited significantly higher chlorophyll-a blooms, net primary production during the southwest monsoon, and pronounced oxygen consumption during fall compared to the other. Our analysis suggest that GRD fuels primary productivity, leading to organic matter abundance and intense oxygen depletion in the subsurface layers, driving the observed shallow OMZ. Understanding the complex interplay between GRD, stratification, upwelling, and biogeochemical processes is crucial for predicting the impact of altered riverine inputs on coastal ecosystems, greenhouse gas emissions, and the overall health of the coastal BoB.

    Keywords: Godavari River Discharge, oxygen minimum zone, chlorophyll-a, Net Primary Production, decomposition

    Received: 19 Apr 2024; Accepted: 17 Sep 2024.

    Copyright: © 2024 Sreejith, Sarma, Sreenivas, Feba, Hoteit and Ashok. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence:
    K S Sreejith, National Institute of Oceanography, Council of Scientific and Industrial Research (CSIR), Dona Paula, India
    Karumuri Ashok, University of Hyderabad, Hyderabad, 500 046, Andhra Pradesh, India

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