ORIGINAL RESEARCH article
Front. Mar. Sci.
Sec. Marine Biogeochemistry
Volume 12 - 2025 | doi: 10.3389/fmars.2025.1632099
This article is part of the Research TopicAnthropogenic Footprints on Marine Ecosystems: Insights into Biogeochemical ShiftsView all articles
Seasonal dynamics of dissolved and particulate organic carbon in nearshore waters of the Andaman Islands
Provisionally accepted
PM Mohan1
Karuna Kumari R1
Joyson Joe Jeevamani J2Mamidala Harikrishnan Prasad22
Sai Elangovan S3N.V.H.K. Chari3Supriyo Chakraborty4
Sachithanandam Veeraragavan2,5*- 1Pondicherry University, Pondicherry, Puducherry, India
- 2National Centre for Sustainable Coastal Management, Chennai, India
- 3Centre for Marine Living Resources and Ecology (CMLRE), Kochi, Kerala, India
- 4Indian Institute of Tropical Meteorology (IITM), Pune, Maharashtra, India
- 5National Institute of Ocean Technology, Chennai, Tamil Nadu, India
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This study investigates the seasonal and spatial variability of hydrochemical parameters and organic carbon pools between the South Andaman Islands (SAI) and North Andaman Islands (NAI) under contrasting monsoonal regimes. Seawater temperature (26.1–33.5 °C) was consistently higher in SAI due to reef-associated stratification, while NAI exhibited greater variability. Salinity (25.2–35.9) and pH were more stable in SAI, whereas NAI showed lower values and higher variability driven by freshwater inputs from the Bay of Bengal river systems. Turbidity and dissolved inorganic nutrients (DIN, DIP, DSi) were significantly higher in NAI, reflecting strong terrestrial and riverine influence. Dissolved organic carbon (DOC; 103–772 µM) and particulate organic carbon (POC; 22–168 µM) concentrations were consistently higher in NAI, particularly during the spring intermonsoon (SIM) and northeast monsoon (NEM), while SAI exhibited lower but more variable concentrations linked to reef metabolism. Seasonal drivers included freshwater and terrestrial inputs enhancing DOC during SIM and NEM, and monsoon-induced mixing reducing concentrations during the southwest monsoon (SWM). POC levels were enriched in NAI throughout, whereas SAI showed greater variability related to reef-derived particulate cycling. The POC:DOC ratio (0.04–0.83) highlighted contrasting biogeochemical regimes, with NAI dominated by particulate-rich terrestrial inputs and SAI characterized by variable phytoplankton-and reef-driven processes. These findings emphasize the role of monsoonal forcing in shaping carbon dynamics across the Andaman Islands and the contrasting influence of terrestrial inputs in NAI versus reef-associated processes in SAI, with implications for regional carbon cycling and ecosystem functioning.
Keywords: Andaman Sea, Coastal waters, dissolved organic carbon, coral reefs, Particulate organic carbon
Received: 20 May 2025; Accepted: 26 Aug 2025.
Copyright: © 2025 Mohan, R, J, Prasad2, S, Chari, Chakraborty and Veeraragavan. 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: Sachithanandam Veeraragavan, National Centre for Sustainable Coastal Management, Chennai, India
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