The Indian Sundarbans: biogeochemical dynamics and anthropogenic impacts

The Sundarbans region is one of the richest ecosystems in the world and is located on one of the world’s largest deltas – the Ganges–Brahmaputra–Meghna system. The Indian Sundarbans have exceptional biodiversity, including rare and globally threatened species, and is made up of a mangrove forest ecosystem with an interconnected network of rivers. The hydrology of the Sundarbans underpin ecosystem health and the potential impact of humans on the region, as the tidal cycle changes water salinity diurnally and freshwater supply changes seasonally with the monsoon. The Indian Sundarbans face multiple pressures with both a reduction in freshwater supply and rising relative sea-level, leading to increased salinization of the mangrove forest. Human-driven alteration of the Sundarbans river catchments is reducing sediment flow, and when coupled with land-use change, is leading to subsidence, deforestation, nutrient enrichment, and heavy metal pollutants impacting the health of the ecosystem. All of these impacts have important ramifications for carbon fluxes that could exacerbate climate change and ecosystem health. In this chapter, we present an overview of our current understanding of biogeochemical dynamics and anthropogenic impacts on the Indian Sundarbans, with a particular focus on water quality, aquatic ecology, and carbon dynamics.