Biodiversity is a measure of the health of ecosystems. The 1992 United Nations Earth Summit defined "biological diversity" as "the variability among living organisms from all sources, including, 'inter alia', terrestrial, marine, and other aquatic ecosystems, and the ecological complexes of which they are part: this includes diversity within species, between species and of ecosystems". In its simplest definition, biodiversity is the number of species in a defined area or a particular taxon. Conservation and sustainable use of biodiversity is fundamental for ecologically sustainable development. India has a rich and varied heritage of biodiversity, encompassing a wide spectrum of habitats from tropical rainforests to alpine vegetation and from temperate forests to coastal wetlands, coral reefs and deep seas. India is the seventh largest country in the world and one of the leading biodiversity rich nations of the world with a mere 2.4% of the world's area, India accounts for 7.31% of the global fauna.

The United Nations designated 2011-2020 as the United Nations Decade on Biodiversity.

Marine biodiversity

India has a vast extent of coast line of about 8129 km and an Exclusive Economic Zone (EEZ) of 2.02 million km², which are home to a diversity of coastal and marine ecosystems, comprising nationally and globally significant biodiversity rich areas. India’s wealth of biodiversity is found in highly diverse marine and coastal habitats. Until today marine diversity is less known than terrestrial biodiversity due to the logistic difficulties of explorations, underwater surveys and collections. Oceans support a large human population in India directly and indirectly.

The Indian Ocean accounts for 29% of the global oceans, 13% of the marine organic carbon synthesis, 10% of the capture fisheries, 90% of the culture fisheries, 30% of the local reefs, and 10% of mangroves. It is pertinent to note that India has 246 estuaries draining a hinterland greater than 200 km3 besides coastal lagoons, mangroves and backwaters. Over 200 species of diatoms, 90 dinoflagellates, 844 algae, 14 seagrasses and 39 mangrove species have been reported from Indian waters. The marine algae include Rhodophyta, Chlorophyta, Phaeophyta and Xanthophyta. Tamil Nadu has the maximum number of species of seaweeds followed by Gujarat and Maharashtra. A number of products such as agar, alginates, carrageenan, liquid fertilizers and bio-active compounds are produced from seaweeds. Foraminiferans (> 500 species), sponges (> 480 species), coelenterates (> 840 species), polychaetes (> 250 species) and echinoderms (> 765 species) have been studied by several researchers. Crustaceans form one of the biggest groups including both commercially important and lesser known organisms. Commercially important groups such as molluscs (> 3370 species) and fishes (>2546 specie-s) are also well documented by the researchers of India. 5 species of sea turtles are also reported from India. Twenty five species of marine mammals belonging to the orders Cetacea and Sirenia are reported from Indian waters.

The coastline of Bay of Bengal and Arabian Sea continues to be a rich fishing ground in the south Asian region and India is one of the world’s largest marine product nations. Indian marine ecosystems are all known for their high biological productivity, which provide a wide range of habitat for many aquatic flora and fauna. It also provides important food resources and critically major services to human beings. Therefore, sustainability of these fragile ecosystems should be our primary concern.

Threats and controls:

It is often argued that the changes in biodiversity will be mainly restricted to land and consequently attention to biodiversity changes in t he ocean is limited. However , humans do impact the already to a considerable degree , especially in the coastal areas but increasingly in the open ocean as well. Over the last thirty years, broad controls have been proposed or developed related to the five major threats. Controls can be categorized with threats (Table 1 below). Many nations have commendable statutes and policies; however implementation failures are widespread.

Amongst these five major threats to marine biodiversity, fishing has, until the present time, been the most damaging on a global scale. The destructive impacts of fishing stem chiefly from overharvesting, habitat destruction, and bycatch. Over the coming century the threats posed by increasing atmospheric greenhouse gases pose huge dangers to the marine environment (Veron 2008, Koslow 2007, Turley et al. 2006). At smaller scales, other threats (particularly pollution and habitat damage) are dominant at different localities. Coral reef, mangrove, estuarine, seagrass, mud-flat, and sponge-field habitats have been (and are being) extensively damaged. River passage, essential for anadromous and diadromous species, has been impaired or destroyed around the globe.

Marine biodiversity conservation approaches

Aquatic conservation strategies support sustainable development by protecting biological resources in ways that will preserve habitats and ecosystems. Methods like Restoration of habitat, Restricted fishing in particular areas, Declaration of biosphere reserves, Control on the establishment of industries, chemical plants and thermal power plants ,Publish the list of threatened or endangered species, Regulation of waste water discharge, Increasing public awareness will helps to conserve the marine ecosystem to a large extent.

Several initiatives were taken by the Government of India focusing on the conservation of wetland, mangroves and coral reef and the management through implementation of law and continuous monitoring. The Wild Life Protection Act of India (1972) provides legal protection to many marine animals. Chapter IV of this Act dealing with sanctuaries, national parks, game reserves and closed areas is applicable to Marine reserves and biospheres also. A National Committee on mangroves, wetlands and coral reefs was constituted in 1993 with a mandate to advise the government on relevant policies and programmes. The mangrove and coral reef areas were declared as ecologically sensitive areas under the Environment Protection Act, 1986. The Coastal Regulation zone (CRZ) notification came in 1991 prohibiting developmental activities and disposal of wastes in the fragile coastal ecosystems. Some of the national parks and sanctuaries in India were declared exclusively as marine protected areas in the 1980s and 1990s. There are a total of 31 major marine protected areas in India. They cover coastal wetlands, especially mangroves, coral reefs and lagoons and have been notified under Wildlife Protection Act, 1972. The three notified Biosphere Reserves in India are the Sundarban Biosphere Reserve, Great Nicobar Biosphere Reserve and the Gulf of Mannar Biosphere Reserve. IUCN has defined a Marine Protected Area as 'any area of intertidal or subtidal terrain, together with its overlaying water and associated flora, fauna, historical and cultural features, which has been reserved by law or other effective means to protect part or all of the enclosed environment'. The country took one more step ahead with the promulgation of the Biological Diversity Act of India2002 and the Biological Diversity Rules 2004. A National Biodiversity Authority with state –level Boards and district-level Management Committees was established under this Act. The main functions of the Authority is to advise the government on matters related to the protection and conservation of biodiversity, sustainable use and equitable sharing of its components, Intellectual Property Rights, etc.

Research in India

The interaction and relationship between the organisms and the environment are not yet quantified ,and we are at present unable to predict the consequences of loss of biodiversity resulting from the change that happening on the ecosystem in ecological, economical or social terms. An important objective of marine biodiversity research should be the necessary knowledge and tools for adequately managing and protecting marine biodiversity. This requires knowledge on genetic and ecological mechanisms that control biodiversity Documentation of biodiversity is an urgent requirement as latest statistics and data on floral and faunal biodiversity of India has not been compiled and documented. Coordination among all organizations/ institutions/NGOS who works for conservation of coastal and marine biodiversity is required for policy developments and awareness creation.