They are the underwater structures that are formed of coral polyps that are held together by calcium carbonate. Another factor that seems to affect the diversity of reef-building corals is the ocean in which they are located. Each polyp consists of three basic tissue layers: an outer epidermis, an inner layer of cells lining the gastrovascular cavity which acts as an internal space for digestion, and a layer called the mesoglea in between (Barnes, R.D., 1987). Coral reefs grow better in shallow water having a depth less than 50 m. The depth of the water should not exceed 200m. The effects of removing fish from a reef have far-reaching implications that go well beyond the fish population and affect the entire food web. While the colony is alive, CaCO3 is deposited, adding partitions and elevating the coral. Coral reefs in the Caribbean are slowly dying! The waves bring food & oxygen needed for coral reefs to survive. NOAA's Coral Reef Conservation Program Coral reefs are often called the rainforests of the sea, both due to the vast amount of species they harbor, and to the high productivity they yield. and Hughes, 1999). Climate change = ocean change. Other coral species are incapable of producing sufficient quantities of CaCO3 to form reefs. Experiments have shown that rates of calcification slow significantly when zooxanthellae are removed from corals, or when corals are kept in shade or darkness (Lalli and Parsons 1995). Aside from climate change, overfishing is one of the biggest threats to coral reefs. Washington D.C.; NOAA. Bermuda, at 32° north latitude, is an exception to this rule because it lies directly in the path of the Gulf Stream’s warming waters (Barnes, R.D., 1987). Thus, the living colony lies entirely above the skeleton (Barnes, R.S.K. Invertebrate Zoology; Fifth Edition. Coral reefs in the Caribbean are slowly dying! 2000. The CRCP brings together expertise from across NOAA for a multidisciplinary approach to managing and understanding coral reef ecosystems. Coral reefs support more species per unit area than any other marine environment, including about 4,000 species of fish, 800 species of hard corals and hundreds of other species. Sponges, sea whips, sea fans, and ahermatypic (non-reef-building) corals become increasingly abundant and gradually replace hermatypic corals in deeper, darker water (Barnes, R.D., 1987; Lalli and Parsons, 1995; Sumich, 1996). The corals’ requirement for high light also explains why most reef-building species are restricted to the euphotic (light penetration) zone, approximately 70 m (Lalli and Parsons, 1995). These compounds, including glucose, glycerol, and amino acids, are utilized by the coral as building blocks in the manufacture of proteins, fats, and carbohydrates, as well as the synthesis of calcium carbonate (CaCO3). Coral reefs are unique (e.g., the largest structures on earth of biological origin) and complex systems. The largest of these coral reef systems is the Great Barrier Reef of Australia, which is more than 1,500 miles (2,400 km) in length. Coral sand is one main player. SSMC4, 10th Floor C. Brown. For the most part, scleractinians are colonial organisms composed of hundreds to hundreds of thousands of individuals, called polyps (Barnes, R.D., 1987; Lalli and Parsons, 1995). According to the records of 2016 and 2017, half of the Great Barrier Reef died due to Coral Bleaching. The topic, ‘Coral Reefs’ is an important topic for the IAS Exam as it is included in the Geographical subject that is an important part of both UPSC Prelims and Mains. We work to protect the world’s coral reefs from the effects of climate change and other human activity. Comprising over 6,000 known species, anthozoans also include sea fans, sea pansies and anemones. Small crabs, shrimps, cowries and other animals reside in the labyrinthine subsurface cavities of the reef crest, protected from waves and predators (Barnes, R.D., 1987; Lalli and Parsons, 1995; Sumich, 1996). The number of species of corals on a reef declines rapidly in deeper water. pp. Below is a list of the threats to coral reefs due to human activities: 1. 92-96, 127-134, 149-162. What is a coral reef? Coral reefs are made up of calcium carbonate. Whereas most undersea ecosystems foster plant growth, coral dominates certain regions because optimal conditions inhibit algae. Coral Reefs are differentiated into three categories based on their shape, nature and mode of occurrence. 3 Types of Coral Reefs . and R.G. These organisms are tiny little animals called polyps. Coral reefs rely heavily on warm water and sunlight to live. Coral reefs survive in water, having a temperature between 20 and 28 degrees Celsius. Threats to coral reefs come from both local and global sources. The one fringing reef in the Palk Bay is 25-30km long, and less than 200m wide lies in the east-west direction of the Pamban channel. But this figure rises to 20-25% in developing countries, and 70-90% in Southeast Asian countries. 1997). This reef has a maximum depth of around 3 m. Situated around a chain of 21 islands, the Gulf of Mannar lies between Tuticorin and Rameswaram at a stretch of 140 km. As members of the phylum Cnidaria, corals have only a limited degree of organ development. Most coral reefs are built from stony corals, whose polyps cluster in groups. Massive corals and encrusting coralline algae thrive in this zone of breaking waves, intense sunlight, and abundant oxygen. Fringing reefs: These reefs grow close to the coast in shallow waters. A coral reef is an underwater ecosystem characterized by reef-building corals. The snowflake coral is known to cause a serious threat to the marine ecosystem due to the following reasons: Coral Reefs – UPSC Notes:- Download PDF Here, Your email address will not be published. The first is a gastrovascular cavity that opens at only one end. Suspended sediments can also serve to decrease the depth to which light can penetrate. Elkhorn coral has large, flattened branches. Almost everywhere we went on the Global Reef Expedition, the big fish were gone from the reef. Coral reefs are considered to be one of the most diverse and valuable ecosystems on earth. Coral reefs are the largest living structure on the planet, and the only living structure to be visible from space. Following the closure of the seaway between the Caribbean and the Pacific, several species of corals became restricted to the Caribbean (Veron 2000). On sunny days, the calcification rates of corals can be twice as fast as on cloudy days (Barnes, R.S.K. They are usually found in shallow areas at a depth less than 150 feet. Coral Reefs are differentiated into three categories based on their shape, nature and mode of occurrence. An Introduction to the Biology of Marine Life, sixth edition. While corals form the backbone of reefs, the reefs are not a one-man show, and they incorporate a variety of plants and animals into their framework. This article will discuss the different characteristics of Coral reefs and its types. Deep channels that slope down the reef face are interspersed between the buttresses. Coral reefs cover less than 1 percent of the Earth’s surface yet feed and shelter a significant amount of marine life, including some 4,000 species … Together, polyps and coenosarc constitute a thin layer of living tissue over the block of limestone they have secreted. The substrate is formed of coral rock and loose sand. Most require very salty (saline) water ranging from 32 to 42 parts per thousand. Coral reefs are the colonies of tiny living creatures that are found in oceans. Small fish inhabit the many holes and crevices on this portion of the reef, and many larger fish including sharks, jacks, barracudas and tunas patrol the buttresses and grooves in search of food (Barnes, R.D., 1987; Lalli and Parsons, 1995; Sumich, 1996). These structures are created by colonies of coral polyps secreting calcium carbonate. Candidates can also download the notes PDF at the end of this article. As much as 90% of the organic material they manufacture photosynthetically is transferred to the host coral tissue (Sumich, 1996). The Andaman and Nicobar Islands fall between 6°-14° N lat and 91 °-94° E longitude. The diversity of reef corals, i.e., the number of species, decreases in higher latitudes up to about 30° north and south, beyond which reef corals are usually not found. Coral reefs are a precious resource in the ocean because of their beauty and biodiversity. How to crochet coral – see the Institute for Figuring’s Crochet Coral Reef – and a TED talkabout it (and the science/maths behind it). A coral reef is a large underwater structure made of dead and living corals (press to see more). Coral reefs are underwater ecosystems that form in tropical waters. Branching corals have branches that also have (secondary) branches. Coral reefs also provide shelter for a wide variety of marine life, humans with recreation, a valuable resource of organisms for potential medicines, create sands for beaches, and serve as … Coral polyps, the animals primarily responsible for building reefs, can take many forms: large reef building colonies, graceful flowing fans, and even small, solitary organisms.Thousands of species of corals have been discovered; some live in warm, shallow, tropical seas and others in the cold, dark depths of the ocean. We welcome your ideas, comments, concerns and suggestions. The last glacial period marked the formation of coral reefs when melting ice caused the sea levels to rise and flood the continental plates. At their base is a hard, protective limestone skeleton called a calicle, which forms the structure of coral reefs. Fringing Reef: The coral reefs that are found very close to the land and forms a shallow lagoon known as Boat Channel are called Fringing Coral Reefs.The Fringing Reefs develop along the islands and the continental margins. Found throughout the tentacles and epidermis, cnidocytes contain organelles called cnidae, which include nematocysts, a type of stinging cell. While the growth patterns of stony coral colonies are primarily species-specific, a colony’s geographic location, environmental factors (e.g., wave action, temperature, light exposure), and the density of surrounding corals may affect and/or alter the shape of the colony as it grows (Barnes, R.D. Digitate corals look like fingers or clumps of cigars and have no secondary branches. It extends outward from the shore; and may be highly variable in character. While these zones vary according to the location and type of reef, the major divisions common to most reefs, as they move seaward from the shore, are the reef flat, reef crest or algal ridge, buttress zone, and seaward slope. Tropical coral reefs cover a mere 0.1 per cent of the ocean but are among the most bio-diverse ecosystems on the planet, supporting one quarter of all marine species. Coral reefs 1. This protects the organism from predators and the elements (Barnes, R.D., 1987; Sumich, 1996). This knowledge will be increasingly valuable as reefs around the world experience problems from pollution, overfishing, boat groundings, climate change, marine debris and disease. Take our website user survey. Coral reefs are often called the rainforests of the sea, both due to the vast amount of species they harbour, and to the high productivity they yield. Tourists coming to dive need not only dive boats and guides, but also restaurants, hotels and commercial and entertainment facilities. The Coral Reef Alliance (CORAL) is a non-profit, environmental NGO that is on a mission to save the world’s coral reefs. The formation of highly consolidated reefs only occur where the temperature does not fall below 18°C for extended periods of time. 1995. 18, 61p. Reefs actually rival old-growth forests in terms of the years they represent [source: NOAA]. Parts of the reef platform may emerge as one or more islands, and breaks in the reef provide access to the central lagoon (Lalli and Parsons, 1995; Levinton, 1995; Sumich, 1996). However, when corals are in this state, they do become more vulnerable to disease and possible death, especially if they are continuously subjected to stress. In addition to a substantial horizontal component, the polyps of colonial corals are connected laterally to their neighbors by a thin horizontal sheet of tissue called the coenosarc, which covers the limestone between the calyxes. Reefbase Aquanaut Survey Manual. As they become larger, a heavier load is placed on the relatively small area attached to the substratum, rendering the colony increasingly unstable. Coral reefs are in decline in the U.S. and around the world. The Coral Reefs included in the GS – I section of the UPSC Syllabus is an important topic to be covered. Other dangers include disease, destructive fishing practices and warming oceans. Tropical coral reefs cover a mere 0.1 per cent of the ocean but are among the most bio-diverse ecosystems on the planet, supporting one quarter of all marine species. The buttress zone serves two main purposes in the reef system. Coral reefs have existed on Earth for 500 million years, providing shelter and food to many generations of ocean life. 1305 East West Highway However, some coral reefs extend even deeper, up to about 450 feet. Without coral reefs many of the world’s most fragile, coastal ecosystems would be unable to thrive. When corals are mentioned, most people think about clear, warm tropical seas and reefs filled with colorful fish. The islands covering an area of 32 km2 consist of 36 tiny islands, 12 atolls, 3 reefs and 5 submerged banks, with lagoons occupying about 4200 km2. When corals are mentioned, most people think about clear, warm tropical seas and reefs filled with colorful fish. As human activities cause increases in greenhouse gases, the climate changes and the ocean becomes more acidic. In fact, the variety of life associated with coral reefs rivals that of the tropical forests of the Amazon or New Guinea. Coral reefs provide about 10% of the fish caught worldwide. At their base is a hard, protective limestone skeleton called a calicle, which forms the structure of coral reefs. In general, massive corals tend to grow slowly, increasing in size from 0.5 cm to 2 cm per year. Due to the warm humid climate of these islands, the temperature of the water varies between 28-31 °C with salinity ranging from 34% – 37%. The State of Coral Reef Ecosystems of the United States and Pacific Freely Associated States. But this figure rises to 20-25% in developing countries, and 70-90% in Southeast Asian countries. The major coral reefs in India includes the Palk Bay, the Gulf of Mannar, the Gulf of Kutch, the Andaman and Nicobar Islands and Lakshadweep Islands. Due to the mud deposits on various coral reefs, these coral reefs are in a highly degraded condition. Oxford, UK: Butterworth-Heinemann Ltd. pp. McManus, J.W., M.C.A. They consume large quantities of the zooplanktons which can have a high ecological impact. Local Threats to Coral Reefs Table corals are table-like structures of fused branches. They are separated from their adjacent land mass by a lagoon of open, often deep water. Coral reefs are the ocean’s most diverse and complex ecosystems, supporting 25% of all marine life, including 800 species of reef-building corals and more than one million animal and plant species. In fact, the variety of life associated with coral reefs rivals that of the tropical forests of the Amazon or New Guinea. Coral reefs also indicate the health of the global ecosystem. Increased greenhouse gases from human activities result in climate change and ocean acidification. Turgeon, D.D. The study of coral reefs is important for providing a clear, scientifically-testable record of climatic events over the past million years or so. It's estimated that ⅙ of the reefs will be dead in the next 20 years! High levels of suspended sediments can smother coral colonies, clogging their mouths which can impair feeding. 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