BPSC (Bihar) Exam  >  BPSC (Bihar) Notes  >  Environment & Additional Topics for State PSC Exams  >  Aquatic ecosystem - (Part - 4)

Aquatic ecosystem - (Part - 4) | Environment & Additional Topics for State PSC Exams - BPSC (Bihar) PDF Download

What Is A Coral Reef?

  • A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups.

Aquatic ecosystem - (Part - 4) | Environment & Additional Topics for State PSC Exams - BPSC (Bihar)

  • Zooxanthellae assist the coral in nutrient production through its photosynthetic activities. These activities provide the coral with fixed carbon compounds for energy, enhance calcification, and mediate elemental nutrient flux. 
  • The coral reef tissues are actually not the coral reef's beautiful colours but are instead clear (white). The corals receive their colouration from the zooxanthellae living within their tissues. 
  • In return, the host coral polyp provides its zooxanthellae with a protected environment to live within and a steady supply of carbon dioxide for its photosynthetic processes. 
  • There are two corals: hard corals and soft corals, such as sea fans and gorgonians. Only hard corals build reefs. 
  • The builders of coral reefs are tiny animals called polyps. As these polyps thrive, grow, then die, they leave their limestone (calcium carbonate) skeletons behind. New polyps colonize the limestone. Therefore, a coral reef is built up of layers of these skeletons covered ultimately by living polyps.
  • The reef-building or hermatypic corals can form a wide range of shapes. Coral reefs may be branched, table-like, or look like massive cups, boulders or knobs. 
  • While most coral reefs are found in tropical and sub-tropical water, there are also deep water corals in colder regions.

Cold Water Corals

  • Cold-water corals inhabit deep, cold (39-55 degrees F), water. The United Nations Environment Programme reports that there are more cold-water coral reefs worldwide than tropical reefs. 
  • There are only about 6 different coral species associated in building with these reefs. The largest cold-water coral reef is the Rost Reef off Norway.


  • They occur in shallow tropical areas where the seawater is clean, clear and warm. 
  • The coral reef cover in Indian waters is roughly estimated up to 19,000 sq. Km. 
  • Coral reefs are one of the most productive and complex coastal ecosystems with high biological diversity. 
  • The high productivity is due to its own primary production and support from its surrounding habitat. 
  • Reef-building corals are a symbolic association of polyps (coral animals) and 'zooxanthellae' (the microscopic algae) 
  • The corals are generally slow-growing colonies of animals while zooxanthellae are fast-growing plants. 
  • Even though corals live in nutrient-poor waters, their capability to recycle the scarce nutrients (by the whole nutrient community) is enormous. 
  • In coral reef ecosystem, many invertebrates, vertebrates, and plants live close to the corals, with tight resource coupling and recycling, allowing coral reefs to have extremely high productivity biodiversity, such that they are referred to as 'the Tropical Rainforests of the Oceans'.

Classification and their location

  • The coral reefs are classified depending on their locations into fringing, patch, barrier and atoll. 
  • The fringing reefs are contiguous with the shore, and they are the most common - by occurring reef form, found in Andamans.
  • Patch reefs are isolated and discontinuous patches, lying shoreward of offshore reef structures as seen in the Palk Bay, Gulf of Mannar and Gulf of Katchchh. 
  • Barrier reefs are linear offshore reef structures that run parallel to coastlines and arise from submerged shelf platforms. The water body between the reef and the shore is termed as a lagoon. Barrier reefs are seen in Nicobar and Lakshadweep. 
  • Atolls are circular or semi-circular reefs that arise from subsiding seafloor platforms as coral reef-building keeps ahead of subsidence. The examples are the atolls of Lakshadweep and Nicobar. 
  • When the reef-building do not keep pace with subsidence, reefs become submerged banks as seen in Lakshadweep. 
  • Seagrasses grow on Kavaratti atoll; mangroves are prevalent on Andaman and Nicobar coral reefs. 
  • Among the four major reef areas of India, Andaman and Nicobar Islands are very rich in species diversity followed by the Lakshadweep Islands, the Gulf of Mannar and finally the Gulf of Kachchh.

Question for Aquatic ecosystem - (Part - 4)
Try yourself:Which of the following region is not suitable for coral reefs?
View Solution

Functions of Coral Reefs

  • Coral reefs are natural protective barriers against erosion and storm surge. 
  • The coral animals are highly adapted for capturing plankton from the water, thereby capturing nutrients 
  • Largest biogenic calcium carbonate producer 
  • They provide substrate for mangroves 
  • Coral reefs provide habitat for a large variety of animals and plants including avifauna.

What are the potential Threats?

(i) Natural causes may be due to the outbreak of reef destroying mechanisms, "bleaching" and depletion of essential symbionts.
(ii) Anthropogenic causes – may be due to chemical pollution (pesticides, cosmetics, etc.), industrial pollution, mechanical damage, nutrient loading or sediment loading, Dredging, shipping, tourism, mining or collection, thermal pollution, intensive fishing, etc.

  • Coral reef ecosystems worldwide have been subject to unprecedented degradation over the past few decades. Disturbances affecting coral reefs include anthropogenic and natural events. Recent accelerated coral reef decline seems to be related mostly to anthropogenic impacts (overexploitation, overfishing, increased sedimentation and nutrient overloading. Natural disturbances which cause damage coral reefs include violent storms, flooding, high and low-temperature extremes, El Nino Southern Oscillation (ENSO) events, subaerial exposures, and predatory outbreaks and epizootics. 
  • Coral reef bleaching is a common stress response of corals to many of the various disturbances mentioned above.

Coral Bleaching

Bleaching or the paling of coral colour occurs when

(i) The densities of zooxanthellae decline and/or
(ii) The concentration of photosynthetic pigments within the zooxanthellae fall.

Aquatic ecosystem - (Part - 4) | Environment & Additional Topics for State PSC Exams - BPSC (Bihar)

  • When corals bleach they commonly lose 60-90% of their zooxanthellae and each zooxanthella may lose 50-80% of its photosynthetic pigments. 
  • If the stress-causing bleaching is not too severe and decreases in time, the affected corals usually regain their symbiotic algae within several weeks or a few months. 
  • If zooxanthellae loss is prolonged, i.e. if the stress continues and depleted zooxanthellae populations do not recover, the coral host eventually dies. 
  • High temperature and irradiance stressors have been implicated in the disruption of enzyme systems in zooxanthellae that offer protection against oxygen toxicity. 
  • Photosynthesis pathways in zooxanthellae are impaired at temperatures above 30 degrees C; this effect could activate coral/algal symbiosis's disassociation. 
  • Low- or high-temperature shocks results in zooxanthellae low as a result of cell adhesion dysfunction. 
  • This involves the detachment of cnidarian endodermal cells with their zooxanthellae and the eventual expulsion of both cell types.

Question for Aquatic ecosystem - (Part - 4)
Try yourself:Where do you find the largest concentration of coral reefs in the world?
View Solution

Ecological causes of coral bleaching

  • As coral reef bleaching is a general stress response, it can be induced by various factors, alone or in combination. It is therefore difficult to unequivocally identify the causes for bleaching events. The following stressors have been implicated in coral reef bleaching events.

Temperature (Major Cause)

  • Coral species live within a relatively narrow temperature margin, and anomalously low, and high sea temperatures can induce coral bleaching. Bleaching is much more frequently reported from elevated seawater temperature. Bleaching events also occur during sudden temperature drops accompanying intense upwelling episodes, seasonal cold-air outbreaks.

Solar Irradiance

  • During the summer months, bleeding during seasonal temperature and irradiance maxima often occur disproportionately in shallow-living corals and on the colonies' exposed summits. Solar radiation has been suspected of playing a role in coral bleaching. Both photosynthetically active radiation (PAR, 400-700nm) and ultraviolet radiation (UVR, 280-400nm) have been implicated in bleaching.

Subaerial Exposure

  • Sudden exposure of reef flat corals to the atmosphere during events such as shallow tides, ENSO-related sea level drops or tectonic uplift can potentially induce bleaching.


  • Relatively few instances of coral bleaching have been linked solely to sediment. It is possible but has not been demonstrated, that sediment loading could make zooxanthellate species more likely to bleach.

Fresh Water Dilution

  • Rapid dilution of reef waters from storm-generated precipitation and runoff has been demonstrated to cause coral reef bleaching. Generally, such bleaching events are rare and confined to relatively small, nearshore areas.

Inorganic Nutrients

  • Rather than causing coral reef bleaching, an increase in ambient elemental nutrient concentrations (e.g. ammonia and nitrate) actually increases zooxanthellae densities 2-3 times. Although eutrophication is not directly involved in zooxanthellae loss, it could cause secondary adverse effects such as lower coral resistance and greater susceptibility to diseases.


  • Zooxanthellae loss occurs during exposure of coral to elevated concentrations of various chemical contaminants, such as Cu, herbicides and oil. Because high concentrations of xenobiotics are required to induce zooxanthellae loss, bleaching from such sources is usually extremely localized and/or transitory.


  • Pathogen induced bleaching is different from other sorts of bleaching. Most coral diseases cause patchy or whole colony death and sloughing of soft tissues, resulting in a white skeleton (not confused with bleached corals). A few pathogens have been identified as the cause of translucent white tissues, a protozoan.

Government Measures to Protect Mangrove Forest and Coral Reefs (Or Coastal Ecosystem)

  • The Government seeks to protect, sustain and augment mangroves and coral reef in the country by both regulatory and promotional measures. 
  • Under the regulatory measures, the Coastal Regulation Zone (CRZ) Notification (2011) and the Island Protection Zone (IPZ) Notification 2011 regulates the development activities along the Seacoast and tidally influenced water bodies.
  • The mangroves and coral reefs areas are categorized as ecological sensitive areas (CRZ-I) where no new constructions are permitted except projects relating to Department of Atomic Energy; pipelines, conveying systems including transmission lines; installation of weather radar for monitoring of cyclones movement and prediction by Indian Meteorological Department and construction of trans harbour sea link and without affecting the tidal flow of water. 
  • To enforce and implement the CRZ and IPZ Notifications, the Ministry of Environment and Forests has constituted the National and State/UT level Coastal Zone Management Authorities.
  • Besides Coral reef is included in Schedule I of the Wild Life Protection Act, 1972 which affords it the highest protection degree. 
  • Further Protected Areas, viz.4 National Parks, 96 Sanctuaries and 3 Marine Biosphere Reserve have been created all over the country under the provisions of the Wild Life (Protection) Act, 1972 to conserve marine life including coral reef. 
  • The Wildlife Crime Control Bureau has also been set up to strengthen law enforcement for control of poaching and illegal trade in wildlife and its products.

Key Initiatives to Protect Marine and Coastal Environments Coastal Ocean Monitoring and Prediction System (Comaps)

  • Being implemented from 1991. 
  • Assesses the health of coastal waters and facilitates management of pollution-related issues
  • Programme was restructured and modified in 2000– 2001 to include pollution monitoring; liaison, regulation and legislation; and consultancy services.

Land-Ocean Interactions in the Coastal Zone (LOICZ)

  • Launched in 1995 
  • Investigates the effects of global change on the coastal zone 
  • Aims to develop, on a scientific basis, the integrated management of coastal environments

Integrated Coastal and Marine Area Management (ICMAM)

  • Launched in 1998 
  • Aims at integrated management of coastal and marine areas. 
  • Model plans for Chennai, Goa and Gulf of Kutch being prepared

Society of Integrated Coastal Management (SICOM)

  • Launched in 2010 
  • A major national initiative to protect coastal ecosystems 
  • A professional body with experts in various aspects of coastal science and management

Institutions for Coastal Management

  • The Notification on Coastal Regulation Zone (CRZ), 1991 (as amended from time to time), aims to protect coastal stretches in India. 
  • India has created institutional mechanisms such as the National Coastal Zone Management Authority (NCZMA) and State Coastal Zone Management Authority (SCZMA) to monitor the CRZ Notification. 
  • These authorities have been delegated powers under Section 5 of the Environmental (Protection) Act, 1986 to take various measures to protect and improve the quality of the coastal environment and prevent, abate, and control environmental pollution in coastal areas.

Ganga Action Plan

  • The Ganga Action Plan was launched on 14th January 1986 with the main objective of pollution abatement, to improve water quality by interception, diversion and treatment of domestic sewage and toxic and industrial chemical wastes present, from identified grossly polluting units entering into the river.
  • After reviewing the effectiveness of the "Ganga Action Plan", the Government announced the "Mission Clean Ganga" project on 31st December 2009 with the objective that by 2020, no municipal sewage and industrial waste would be released in the river without treatment, with the total budget of around Rs.15,000 crore.
  • The Government also established the National Ganga River Basin Authority (NGRBA), chaired by the Prime Minister, intending to ensure effective abatement of pollution and conservation of the river Ganga, by adopting a river basin approach for comprehensive planning and management.

Question for Aquatic ecosystem - (Part - 4)
Try yourself:Where do you find the atoll coral reefs in India?
View Solution

Namami Ganga Program

  • Accordingly, an Integrated Ganga Conservation Mission called "Namami Gange" has been proposed to be set up and a sum of Rs. 2,037 crores have been set aside for conservation and improvement of the Ganga. 
  • Besides a sum of Rs. 100 crores have been allocated for Ghats and beautification of River Fronts at Kedarnath, Haridwar, Kanpur, Varanasi, Allahabad, Patna, and Delhi financial year. 
  • Accordingly, Namami Gange approaches Ganga Rejuvenation by consolidating the existing ongoing efforts and planning for a concrete action plan for the future.
  • The Ghats and River fronts' interventions will help better citizens connect and set the tone for the river-centric urban planning process.

Following are proposed to be taken up under Namami Gange program

(i) Nirmal Dhara- ensuring sustainable municipal sewage management

  • Project prioritization in coordination with the Ministry of Urban Development. 
  • The incentive for states to take up projects on Ganga Main-stem by providing an additional share of central grants for sewerage infrastructure. 
  • Uniform standards for both MoU D scheme and Namami Gange programme, 10 years mandatory O&M by the same service provider at par with NGRBA programme and PPP, Mandatory reuse of treated water 
  • Expanding coverage of sewerage infrastructure in 118 urban habitations on banks of Ganga- estimated cost by MoUD is Rs 51000 Crores

(ii) Nirmal Dhara- managing sewage from Rural Areas

  • Ministry of Drinking Water and Sanitation scheme for all Ganga bank Gram Panchayats (1632) free from open defecation by 2022, at the cost of Rs 1700 Crores as central share

 (iii) Nirmal Dhara- managing Industrial discharge

  • Making Zero Liquid Discharge mandatory 
  • Rationalized water tariff to encourage reuse 
  • Real-time water quality monitoring

(iv) Aviral Dhara

  • Enforcing River Regulatory Zones on Ganga Banks 
  • Rational agricultural practices, efficient irrigation methods 
  • Restoration and conservation of wetlands

(v) Ensuring ecological rejuvenation by conservation of aquatic life and biodiversity
(vi) Promotion of Tourism and Shipping in a rational and sustainable manner
(vii) Knowledge Management on Ganga through Ganga Knowledge Centre leading to a Ganga University of River Sciences

NRI Ganga Fund

NRIs have been a significant contributor to India's development process in education, health, and preservation of culture. In this context, to harness their enthusiasm to contribute to the conservation of the river Ganga, the NRI Fund for Ganga will be set up to finance special projects. NRI Ganga Fund could be set up under the Ministry of Overseas Indian Affairs or Ministry of Finance, focusing on funds sourcing and corpus management.

Clean Ganga Fund

The main features of "Clean Ganga Fund (CGF)" are: Considering that there is a need to increase people's participation from across the country and abroad, it is proposed to set up a "Clean Ganga Fund (CGF)" with voluntary contributions.

  • CGF will contribute to the national effort of improving the cleanliness of the river Ganga with the contributions received from the residents of the country, NRIs/ PIO and others. 
  • CGF will be operated through a bank account by a Trust to be headed by the finance minister. The secretariat of the Trust will be set up in Ministry of Water Resources, River Development and Ganga Rejuvenation under the Mission Director, Clean Ganga. 
  • Domestic donors to the fund shall be eligible for tax benefits as in the case of "Swachch Bharat Kosh". Foreign donors could get suitable tax exemptions in domestic law, wherever permissible. 
  • CGF will explore the possibility of setting up daughter funds in other jurisdictions/countries of high donor interest such as USA, UK, Singapore, UA E, etc. to enable tax benefits to donors in their respective jurisdictions. 
  • CGF will be catalytic in nature and identify and fund specific projects, such as pilot projects, R&D projects, innovative projects, or other focused projects. The Fund will define specific and measurable objectives to form the basis for planning, funding, and evaluation.

Broad activities that will be financed from the Clean Ganga Fund (CGF) Fund are

  • Activities outlined under the 'Namami Gange' programme for cleaning of river Ganga. 
  • Control of non-point pollution from agricultural runoff, human defecation, cattle wallowing, etc. 
  • Setting up of waste treatment and disposal plants along the river around the cities. 
  • Conservation of the biotic diversity of the river.
  • Community-based activities to reduce polluting human interface with the river. 
  • Development of public amenities, including activities such as Ghat redevelopment. 
  • Research and Development, and innovative projects. 
  • Research and Development projects and innovative projects for new technology and processes for cleaning the river. 
  • Independent oversight through intensive monitoring and real-time reporting. 
  • Any other activity as approved by the Trust.

Recent Measures

  • Union Environment Ministry has taken up a new strategy for conservation and rejuvenation of major river water systems. The new strategy considers the entire river basin, which is contributing its flow to the particular river stretch for conservation. 
  • The present strategy for conservation of rivers is limited only to tackling pollution load from domestic wastewater and regulation of industrial pollution. The new approach is a holistic one for rejuvenating rivers, wherein water management and environment management are taken together to restore the lost ecology of the polluted stretches of the rivers.
The document Aquatic ecosystem - (Part - 4) | Environment & Additional Topics for State PSC Exams - BPSC (Bihar) is a part of the BPSC (Bihar) Course Environment & Additional Topics for State PSC Exams.
All you need of BPSC (Bihar) at this link: BPSC (Bihar)
31 videos|121 docs|28 tests

Up next

FAQs on Aquatic ecosystem - (Part - 4) - Environment & Additional Topics for State PSC Exams - BPSC (Bihar)

1. What is a coral reef?
A coral reef is a diverse underwater ecosystem made up of calcium carbonate structures produced by living organisms called coral polyps. These reefs are formed over long periods of time and are found in clear, shallow, warm waters of the tropics and subtropics.
2. How are coral reefs formed?
Coral reefs are formed through a process called coral calcification. Coral polyps, tiny animals that secrete calcium carbonate, create a hard exoskeleton around their soft bodies. Over time, as more and more polyps build their exoskeletons on top of each other, coral reefs are formed.
3. What is the significance of coral reefs?
Coral reefs are of great ecological importance. They provide habitat and shelter for a wide variety of marine organisms, including fish, crustaceans, and sponges. Coral reefs also protect coastlines from erosion, provide a source of food for local communities, and contribute to tourism and recreational activities.
4. How are coral reefs threatened?
Coral reefs are facing numerous threats, primarily due to human activities. These include pollution, overfishing, destructive fishing practices, climate change, and ocean acidification. These factors can lead to coral bleaching, where corals lose their colorful algae and become vulnerable to disease and death.
5. How can we protect coral reefs?
Protecting coral reefs requires a combination of local and global efforts. Some key actions include reducing pollution and runoff, implementing sustainable fishing practices, establishing marine protected areas, and promoting awareness and education about the importance of coral reefs. Additionally, addressing climate change and reducing greenhouse gas emissions is crucial for the long-term survival of coral reefs.
31 videos|121 docs|28 tests
Download as PDF

Up next

Explore Courses for BPSC (Bihar) exam
Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
10M+ students study on EduRev
Related Searches

study material


Sample Paper


Extra Questions






past year papers




Aquatic ecosystem - (Part - 4) | Environment & Additional Topics for State PSC Exams - BPSC (Bihar)


Semester Notes


Objective type Questions


Previous Year Questions with Solutions


practice quizzes




Aquatic ecosystem - (Part - 4) | Environment & Additional Topics for State PSC Exams - BPSC (Bihar)


Important questions


Viva Questions


shortcuts and tricks


mock tests for examination


Aquatic ecosystem - (Part - 4) | Environment & Additional Topics for State PSC Exams - BPSC (Bihar)


video lectures