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

India is bordered in the soutii, south-west, and south-east with Indian Ocean, Arabian Sea (AS), and the Bay of Bengal (BOB), respectively. Indian coast is 7517 km long comprising 5423 km in the peninsular India and 2094 km in Andaman and Nicobar, and Lakshadweep Islands. The Indian exclusive economic zone (EEZ) is spread in 2.02 million sq km (0.86 million sq km in west coast, 0.56 m illion sq km in east coast and 0.6 million sq km in Andaman and Nicobar Islands). The Indian marine environmentconsisting of adjoining coastal areas and EEZ directly sustains useful habitats and suppons the livelihood of 3.9 million fishers. Nearly 25% of the country’s population resides in these areas and about 340 communities are primarily occupied in marine and coastal fisheries (MoEF, 2009; SACEP, 2014). Nitrogen (N) exists in various chemical forms, produced by marine biota through several chemical transformations during their growth and metabolism in the marine environment. Nitrogen as N2 is generally unavailable in marine conditions and thereby, the equilibrium of the processes of N2 fixation (conversion of atmospheric N2 to organic nitrogen) and denitrification (conversion of nitrate to N2) decides the bioavailable nitrogen supply and productivity (Gruber, 2008)