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General Knowledge Cluster80 Verified Questions
Coral Reefs of India GK Questions & Answers
Coral reefs represent highly productive marine ecosystems formed through a mutualistic endosymbiosis between scleractinian (stony) coral polyps and photosynthetic dinoflagellates belonging to the genus Symbiodinium (zooxanthellae). Corals secrete calcium carbonate (aragonite) exoskeletons in shallow, oligotrophic marine waters requiring temperatures between 23°C and 29°C and normal oceanic salinity (32 to 35 parts per thousand). In India, major coral formations occur across four principal regions: the fringing reefs of the Gulf of Mannar Biosphere Reserve, the extensive fringing and barrier reefs of the Andaman and Nicobar Islands, the pristine coral atolls of Lakshadweep, and the patch and fringing reefs of the Gulf of Kutch Marine National Park. These biogenic structures face critical threats from coral bleaching—a phenomenon wherein thermal stress induced by elevated sea surface temperatures causes the expulsion of symbiotic algae, resulting in coral starvation and mortality. Ocean acidification, driven by elevated atmospheric carbon dioxide absorption, further reduces marine carbonate ion saturation states, impairing calcification. In India, all scleractinian corals are afforded the highest legal protection under Schedule I of the Wildlife (Protection) Act, 1972, and the Coastal Regulation Zone (CRZ) notifications.
High-yield conceptual summaries for competitive exams and rapid revision.
Coral reefs depend on a symbiotic relationship between anthozoan coral polyps and photosynthetic zooxanthellae (genus Symbiodinium).
India hosts major coral reefs in four primary zones: Andaman and Nicobar Islands, Lakshadweep atolls, Gulf of Mannar, and Gulf of Kutch.
Reef-building corals require shallow, clear waters with temperatures between 23°C and 29°C and salinity levels of 32 to 35 parts per thousand.
Coral bleaching occurs when thermal stress or acidification forces corals to expel symbiotic algae, leaving white calcium carbonate skeletons.
All hard coral species in India receive statutory protection under Schedule I of the Wildlife (Protection) Act, 1972, and CRZ-I regulations.
Showing 25 Curated Questions80 Total in Bank
1ID: GK-OCEN-00034
easyOcean Currents, Topography & Marine Ecology
What is the primary biological cause of large-scale mass 'coral bleaching' events observed across tropical coral reef ecosystems?
Verified Explanation
Elevated ocean temperatures stress reef-building corals, causing them to expel their intracellular symbiotic microalgae (zooxanthellae). Without these photosynthetic algae, the coral loses its colour and primary energy source, turning stark white.
2ID: GK-OCEN-00095
easyOcean Currents, Topography & Marine Ecology
What is the world's largest coral reef ecosystem, stretching over 2,300 kilometres along the north-eastern coast of Australia in the Coral Sea?
Verified Explanation
The Great Barrier Reef off Queensland, Australia, is the world's largest living coral reef structure, spanning over 2,300 km and composed of over 2,900 individual reefs and 900 islands. It was inscribed as a UNESCO World Heritage Site in 1981.
3ID: GK-OCEN-00098
mediumOcean Currents, Topography & Marine Ecology
According to Charles Darwin's 1842 theory of coral reef geomorphology, what is the correct evolutionary sequence in the formation of a coral atoll?
Verified Explanation
In 'The Structure and Distribution of Coral Reefs' (1842), Charles Darwin hypothesized that coral reefs evolve in a three-stage sequence: initial fringing reefs form directly along the volcanic island shore; as the island gradually subsides, corals grow upward forming an offshore barrier reef separated by a lagoon; and upon complete submergence of the island, an annular ring of coral reef (an atoll) enclosing a lagoon remains.
4ID: GK-OCEN-00297
easyOcean Currents, Topography & Marine Ecology
During mass coral bleaching events induced by marine heatwaves, what photosynthetic endosymbiotic microalgae are expelled by stony coral polyps?
Verified Explanation
Stony corals live in a mutualistic symbiosis with photosynthetic dinoflagellates called zooxanthellae (family Symbiodiniaceae) that reside within their tissues. When seawater temperatures exceed local summer maxima by 1–2 °C, thermal stress impairs the algal photosynthetic apparatus, prompting the coral host to expel the zooxanthellae, revealing the stark white calcium carbonate skeleton.
5ID: GK-OCEN-00309
easyOcean Currents, Topography & Marine Ecology
Located in the Coral Sea off the coast of Queensland, Australia, what is the world's largest living biogenic coral reef structure?
Verified Explanation
The Great Barrier Reef, spanning over 2,300 km along the northeastern coast of Australia in the Coral Sea, is the world's largest coral reef system. Comprising roughly 3,000 individual reefs and 900 islands built by billions of tiny coral polyps, it was designated a UNESCO World Heritage Site in 1981.
6ID: GK-OCEN-00333
easyOcean Currents, Bathymetry & Marine Ecology
What biological event occurs during marine heatwave events when stressed coral polyps expel their symbiotic photosynthetic algae?
Verified Explanation
Elevated sea surface temperatures cause corals to expel their endosymbiotic dinoflagellates (zooxanthellae), exposing the white calcium carbonate skeleton in a phenomenon known as coral bleaching.
7ID: GK-OCEN-00392
easyOcean Currents, Bathymetry & Marine Ecology
Coral bleaching is caused by the expulsion of which photosynthetic endosymbiotic microalgae from coral polyp tissues during marine heatwaves?
Verified Explanation
Corals maintain a mutualistic symbiosis with photosynthetic dinoflagellates called Zooxanthellae (family Symbiodiniaceae). Prolonged elevated sea surface temperatures induce thermal stress that damages the algae's photosynthetic apparatus, causing the coral host to expel them and expose its white calcium carbonate skeleton.
8ID: GK-OCEN-00474
easyOcean Currents, Bathymetry & Marine Ecology
What is the primary biological and physiological cause of mass coral bleaching observed during marine heatwaves across tropical coral reefs?
Verified Explanation
Reef-building stony corals live in an obligate mutualistic symbiosis with photosynthetic dinoflagellates (zooxanthellae) living inside their gastrodermal tissues. When elevated sea surface temperatures exceed local thermal thresholds by 1-2°C, the algal photosynthetic apparatus produces toxic reactive oxygen species, prompting the coral host to expel the algae, leaving behind a white, transparent calcium carbonate skeleton.
9ID: GK-OCEN-00490
hardOcean Currents, Bathymetry & Marine Ecology
What is the Coral Triangle, and why is it globally recognized by marine conservation scientists as the epicentre of marine biodiversity ('the Amazon of the seas')?
Verified Explanation
The Coral Triangle spans nearly 6 million square kilometres across six Southeast Asian and Pacific nations. It contains over 600 reef-building coral species (76% of the global total), more than 2,000 coral reef fish species (37% of global total), and six of the world's seven marine turtle species, representing the highest marine biodiversity density on Earth.
10ID: GK-OCEN-00348
easyOcean Currents, Bathymetry & Marine Ecology
Which is the world's largest coral reef system, extending over 2,300 kilometres off the north-eastern coast of Australia?
Verified Explanation
The Great Barrier Reef, a UNESCO World Heritage Site off Queensland, Australia, is the world's largest biogenic structure composed of over 2,900 individual reefs and 900 islands.
11ID: GK-OCEN-00523
mediumUNCLOS, Exclusive Economic Zones & Blue Economy
Which Marine National Park, established in 1986 in Tamil Nadu, represents India's first marine biosphere reserve, renowned for dugongs, sea turtles, and pristine coral reefs?
Verified Explanation
The Gulf of Mannar Marine National Park, spanning 21 islands off the coast of Ramanathapuram and Thoothukudi in Tamil Nadu, was established in 1986. It forms the core area of the Gulf of Mannar Biosphere Reserve, harboring rich seagrass beds that support the endangered Dugong dugon.
12ID: GK-ENV-00497
mediumNational Parks & Wildlife Sanctuaries
Which National Park in the Andaman and Nicobar Islands is famous for protecting pristine coral reefs and sea cows (Dugongs)?
Verified Explanation
Mahatma Gandhi Marine National Park at Wandoor in South Andaman was established in 1983 to protect marine life, including diverse coral reefs, nesting sea turtles, and endangered dugongs (sea cows).
13ID: GK-STUT-00347
easyNortheast States & Island Territories
Agatti, Kavaratti, Kadmat, and Kalpeni are major inhabited coral atoll islands belonging to which Indian archipelago?
Verified Explanation
Agatti, Kavaratti (the administrative capital), Kadmat, Kalpeni, and Minicoy are prominent atolls of the coral archipelago of Lakshadweep in the Arabian Sea.
14ID: GK-STUT-00526
easyNortheast States & Island Territories
Which island territory in the Arabian Sea consists entirely of coral atolls and reefs?
Verified Explanation
Lakshadweep is an archipelago of 36 coral islands and atolls located in the Arabian Sea off the Malabar coast.
15ID: GK-WILD-00131
easyFamous National Parks of India
Mahatma Gandhi Marine National Park (Wandoor), known for its coral reefs and marine life, is situated in which Union Territory?
Verified Explanation
Mahatma Gandhi Marine National Park was established in 1983 at Wandoor in South Andaman to protect sea turtles and coral reefs.
16ID: GK-WGEOG-00576
hardContinents Oceans
The Great Barrier Reef, the world's largest coral reef system extending over 2,300 kilometers, is located in which marginal sea off the northeastern coast of Australia?
Verified Explanation
The Great Barrier Reef is situated in the Coral Sea off the coast of Queensland, comprising over 2,900 individual reefs and 900 islands.
17ID: GK-WGEOG-00604
easyContinents Oceans
The Great Barrier Reef, the world's largest coral reef system, is located off the coast of which Australian state?
Verified Explanation
The Great Barrier Reef stretches for over 2,300 kilometers in the Coral Sea off the northeastern coast of Queensland, Australia.
18ID: GK-OCEN-00009
hardOcean Currents, Bathymetry & Marine Ecology
Which was the first designated Marine National Park in India, established in 1982 to protect coral reefs, mangroves, and diverse marine intertidal ecosystems?
Verified Explanation
The Marine National Park in the Gulf of Kutch, Gujarat, was declared India's first marine national park in 1982 (after the sanctuary was established in 1980). It encompasses an archipelago of 42 islands with extensive coral formations and mangrove ecosystems.
19ID: GK-OCEN-00043
mediumOcean Currents, Topography & Marine Ecology
The Gulf of Mannar Marine Biosphere Reserve, India's first marine biosphere reserve renowned for its coral reefs and the vulnerable sea cow (Dugong dugon), is located along the coast of which state?
Verified Explanation
The Gulf of Mannar Biosphere Reserve encompasses 21 islands and adjacent coastal waters along the Ramanathapuram and Thoothukudi districts of Tamil Nadu, serving as a vital sanctuary for dugongs, dolphins, and diverse coral reefs.
20ID: GK-OCEN-00175
easyUNCLOS, EEZ & Blue Economy Policy
Located along the southeastern coast of Tamil Nadu, which was the first Marine National Park established in India (in 1986), comprising a chain of 21 uninhabited coral islands?
Verified Explanation
The Gulf of Mannar Marine National Park in Tamil Nadu consists of 21 offshore islands and adjacent coral reefs spanning Rameswaram to Tuticorin. Established in 1986, it was recognized as India's first marine biosphere reserve in 1989, harboring dugongs, sea turtles, and over 100 coral species.
21ID: GK-WILD-00240
hardFamous National Parks of India
India's first Marine National Park, created in 1982 to protect coral reefs, sponges, and mangrove creeks across 42 islands, is located in which gulf in Gujarat?
Verified Explanation
Marine National Park in the Gulf of Kutch near Jamnagar was declared India's first marine national park in 1982, protecting 110 species of corals and 7 species of mangroves.
22ID: GK-WILD-00315
mediumFamous National Parks of India
Marine National Park in the Gulf of Kutch, India's first designated marine national park created in 1982 to protect coral reefs and mangroves, is located in which state?
Verified Explanation
The Marine National Park in the Gulf of Kutch covers 42 islands along the Jamnagar coast of Gujarat, protecting live corals, sponges, sea anemones, and dugongs.
23ID: GK-RECD-00574
hardNature Wildlife Extremes
What is the world's largest living structure and largest coral reef system, stretching over 2,300 kilometres (1,400 miles) over an area of ~344,400 sq km off the coast of Queensland, Australia?
Verified Explanation
The Great Barrier Reef is composed of over 2,900 individual reefs and 900 islands, so vast it can be seen from space, and is home to thousands of marine species.
24ID: GK-OCEN-00117
mediumUNCLOS, EEZ & Blue Economy Policy
Under India's Coastal Regulation Zone (CRZ) Notification, 2019, which category specifically designates 'Ecologically Sensitive Areas' such as mangroves, coral reefs, turtle nesting grounds, and horseshoe crab habitats?
Verified Explanation
Under the CRZ Notification 2019, CRZ-I is divided into CRZ-I A (Ecologically Sensitive Areas including mangroves, corals, salt marshes, turtle nesting sites) where no new construction is permitted except essential defense/strategic projects, and CRZ-I B (the intertidal zone between Low Tide Line and High Tide Line).
Why are cold-water deep-sea coral reefs considered ecologically vital despite living in total darkness below 200 metres depth?
Verified Explanation
Cold-water corals (such as Lophelia pertusa) build intricate biogenic reef structures on continental slopes and seamounts, creating biodiversity hotspots that serve as feeding, nursery, and spawning grounds for deep-sea fish and invertebrates.