Reactive Nitrogen in Coastal and Marine Waters of India and Its Relationship With Marine Aquaculture

The Indian marine environment, consisting of adjoining coastal areas and the exclusive economic zone (EEZ), directly sustains useful habitats and supports the livelihood of 3.9 million fishers. The average marine fisheries production of the country during the period 2010–2015 has been estimated at 3.36 million tons consisting of approximately 667 different fish species inhabiting the neritic zone that depend on the productivity of marine ecosystem and in turn are influenced by the reactive nitrogen (Nr) available in the system. During the past three decades significant advances have been made in industry, agriculture, fisheries, and other sectors and these have resulted in the release of Nr influencing the N-cycle in the coastal and marine ecosystems. Nitrogen assessment of the surface waters carried out in the EEZ and adjoining areas during the years 1998–2007 revealed that the annual concentrations (μM) of NO 2 ranged from 0 to 0.4, 0 to 0.6, and 0 to 0.7 in the Arabian Sea, Bay of Bengal, and Andaman Sea, respectively. The corresponding values for NO 3 (μM) were 0–2.5, 0–3, and 0–3.5, respectively. Nr transfer to the marine environment also influences eutrophication, algal blooms, changes in the ecological processes and habitats affecting ecosystem health. In this chapter, the present status of Nr assessment in the coastal and marine ecosystems in the country has been reviewed, its interaction with marine aquaculture listed, and the need for future research thrusts, especially on prediction of the extent and direction of impacts of altered nitrogen fluxes on the coastal and marine resources including diversity of faunal and floral community structure is discussed.