International Journal of Science and Research (IJSR) ISSN: 2319-7064 ResearchGate Impact Factor (2018): 0.28 | SJIF (2019): 7.583 Volume 9 Issue 7, July 2020 www.ijsr.net Licensed Under Creative Commons Attribution CC BY A Review to Coral Reef Ecosystem: A Critical Habitat to Look after for Conservation of Marine Biodiversity Suman Nama Fisheries Resource Harvest and Post-Harvest Management Division ICAR‐Central Institute of Fisheries Education, Pinch Marg, Off Yari Road, Versova, Mumbai 400061, India Abstract: Corals are found in tropical and sub-tropical world’s oceans. Corals are the most diversified, economically, and ecologically valuable ecosystems. Reef ecosystem covers 0.1% area of the world and supports 25% of ocean life, including fish, crustaceans, mammals, sponges, and echinoderms. Corals are also known as Rainforests of the Sea’ because of the native biodiversity. Coral reefs provide economic, social, cultural, and ecosystem services. Despite providing immense ecosystem services, corals are degraded to a great extent due to climate change, anthropogenic threats, Coastal development, overfishing, and destructive fishing practices. This magnificent creature of nature needs to be protected by adopting management and conservation strategies recommended by national and international authorities. Some advanced management methods like satellite-based study (mapping, monitoring) and coral gardening adaptation are essential for obtaining maximum benefits out of the reefs ecosystem without harming it. Keywords: Coral reef, Rainforest, echinoderms, mapping, overfishing. 1. Introduction Coral reef ecosystem is the most diverse, ancient, and highly productive underwater ecosystem, but they are sensitive and fragile to environmental changes. Coral belongs to the phylum Cnidaria, and class Anthozoa in the animal. Generally, corals are available throughout the world oceans, but reef-building coral (hermatypiccorals) is found in the ocean's tropical and subtropical region (300N and 300S latitudes). Coral mostly grows in shallow, bright, warm, and agitated water. Coral reefs are essential marine resources in the tropical and subtropical regions of the world ocean (Spalding et al.,2001). Reefs occur in less than 0.1 percent of the ocean area, yet they provide shelter for 25% of all marine species (Spadling et al., 2001).Apart from the biodiversity, coral also plays a crucial role in shoreline protection, revenue generation, and employment generation. Different species of corals found in different ocean basins of the world. The reefs in the tropical western Atlantic Oceanlook different from the reefs in the Indo-Pacific region. The structure and Reef type are differing from area to area. The types of reefs included are 1) Fringing reefs: They reefs are directly attached to the shore and grow towards the sea. Also known as shore reefs. These are found in Andaman and Nicobar Islands, Gulf of Mannar and Palk Bay. 2) Barrier reefs: These are separated from a mainland or island shore by a lagoon and are present in Andaman and Nicobar Islands. Barrier reefs are found in Australia (The great barrier reef). 3) Platform Reefs: Platform reefs are almost flat reefs without any lagoon. They may associate with the coast and a barrier reef. These reefs are found in the Gulf of Kutch of India. 4) Atolls: Atolls are circular or continuous barrier reefs and extend around a lagoon without a central island. Lakshadweep is the only atoll union territory of India. Although coral provides various ecological, regulatory, provisional, and cultural services, their habitat isdegraded and destroyed due to the several natural and anthropogenic activities such as climate change, storms, hurricanes, pollution, coral mining, anchoring. Zones of the coral reef: There are three distinct zones of coral reef contained in a coral reef, i.e., the fore reef, reef crest, and the back reef (frequently referred to as the reef lagoon) which support different types of life forms. The reefs generally occur less than 50m water depth, and the reefs are ecologically and physically interlinked. The reef lagoon is an entirely enclosed area, and it is less affected by wave action and often contains small reef patches (Moyle et al., 2004). Locations of corals: Coral reefs cover an area of about 284,300 km^2 (109,800 sq mi), which is just under 0.1% of the oceans' surface area (UNEP 2001).The Indo-Pacific region (including the Indian Ocean, Southeast Asia Red Sea, and the Pacific) accounts for 91.9% of this area. Southeast Asia contributes 32.3% of that area, while the Caribbean and Atlantic coral reefs account for 7.6% and Pacific, including Australia, which accounts for 40.8% of that figure (Spadling et al., 2001).The optimum temperature for growth of the most coral reefs is 26–27 °C, and few reefsexist in waters below 18 °C (Achituvand Dubinsky, 1990).However, the reefsin the Persian Gulf have adapted to temperatures of38 °C (100 °F) in summer and 13 °C (55 °F) in winter (Wells and Nick, 1992).Coral reefs are scared along the west coasts of Africa and America primarily due to intense cold coastal currents and upwelling (the Benguela, Canary Currents, and Peru respectively) that makes water temperatures below the optimum level for coral growth in these areas (Nybakken and James, 1997). Corals are scarcely found along the coastline of South Asia Myanmar borders and from the eastern tip of India (Chennai) to the Kolkata and as well as Bangladesh and along the north-eastern South American Paper ID: SR20720222158 DOI: 10.21275/SR20720222158 1664