CORAL REEFS AND ATOLLS
18.1 CORAL REEFS – INTRODUCTION
- In Tropical seas, many kinds of coral animals and marine organisms such as coral polyps, calcareous algae, shell forming creatures and lime-secreting plants live in large colonies. Though they are very tiny creatures, their ability to secrete tiny cells has given rise to a peculiar type of marine landform.
- Coral Reefs and Atolls are significant submarine features.
- These are formed due to accumulation and compaction of skeletons of lime secreting organisms known as Coral Polyps.
- Among the coral animals, polyps are the most abundant and also the most important.
- Coral polyps thrive in the tropical oceans confined between 25° N – 25° S latitudes and live on lime.
- The photosynthetic unicellular plant alga, which are embedded in the tissues of outer bodies of coral animals (polyps) are called zooxanthellae alga. These algae are also called symbiotic partners of coral animals.
- Numerous coral polyps live at a place, in groups in the form of colony and form calcareous shells around them.
- Coral reefs are formed due to formation of one shell upon another shell along submarine platforms at suitable depth.
- Since coral polyps, cannot survive above water level and hence coral reefs are always found either upto sea level and below it.
- They are generally attached to submarine platforms or islands submerged under sea water.
- Coral reefs have about 1,00,000 species of which 10% only have been so far studied. Coral reefs are more diverse than the tropical rainforests and hence coral reefs are called rainforests of the oceans.
18.2 CONDITIONS FOR THE GROWTH OF CORAL POLYPS
- Corals are found mainly in the tropical oceans and seas because they require high mean annual temperature ranging between 20° – 21° C for their survival. They cannot survive in the waters having either very low or very high temperature.
- Corals do not live in deeper waters (not more than 60-77 m) below sea level because they require sufficient sunlight and oxygen, which are very much required for the growth of polyps.
- There should be clean and sediment free water, because muddy water or turbid water clogs the mouth of coral polyps and resulting into their death.
- At the same time, fresh water is also injurious for the growth of corals. Hence, corals avoid coastal lands and live away from the area of river mouths.
- Very high proportion of oceanic salinity is injurious for the growth of coral polyps because such waters contain little amount of calcium carbonates, whereas lime is important food for coral polyps.
- The oceanic salinity ranging between 27% and 30% is most ideal for the growth and development of coral polyps.
- Ocean currents and waves are favourable for corals because they bring necessary food supply for the polyps. Therefore, corals grow in open seas and oceans, but they cannot survive in lagoons and small enclosed seas because of lack of supply of food.
- Currents and waves also determine the shape of the coral reefs.
- There should be extensive submarine platforms for the formation of colonies by the coral polyps. Such platforms should not be more than 50 fathoms below sea level. The polyps start from their colonies from a firm base of hard rocks and grow upward until they reach the sea level. Besides, polyps also grow outward from the submarine platforms.
18.3 TYPES OF CORAL REEFS
The submarine coral reefs are classified in two ways
- I. Fringing reef
- II. Barrier reef
- III. Atoll reef
TYPES OF REEFS
2. On the basis of location
- I. Tropical coral reefs
- II. Marginal belt coral reefs
I. FRINGING REEF
- Coral reefs developed along the continental margins or along the islands are fringing reefs.
- The seaward slope is steep and vertical while the landward slope is gentle.
- The upper surface is uneven and corrugated.
- Though fringing reefs are usually attached to the coastal land but sometimes there is gap between them and land and thus lagoon is formed between the fringing reef and the land. Such lagoon is called boat channel.
- Coral reefs are generally long but narrow in width.
- The continuity of coral reefs is broken wherever rivers drain into the seas and oceans.
Coral reefs are basically of two types.
- i. Coral reefs facing open ocean and
- ii. Coral reefs protected by a barrier (found in Sakau Island, southern Florida)
II. BARRIER REEF
- Barrier reefs are the largest, most extensive, highest and widest reefs of all types of coral reefs.
- A barrier reef is separated from the coast by a much wider and deeper channel or lagoon. These reefs are parallel to the coastal platforms. The reef is partially submerged.
- The average slope is about 45° but some barrier reefs are characterised by 15°-25° slope.
- Great Barrier Reef is located parallel to the east coast of Australia, is the largest of all the barrier reefs of the world. This reef is located between 9°S to 22°S latitudes and stretches for 1920 km.
- The depth of lagoon between the coast and the reefs is 240 feet, whereas the width ranges between 7 to 80 miles.
- The reef is broken at places and hence there are frequent openings in the form of tidal inlets which enable the lagoon to maintain contacts with the open ocean.
- A ring of narrow growing corals of horseshoe shape and crowned with palm trees are called Atoll.
- It is generally found around an island or in elliptical form on a submarine platform.
- There is a lagoon in the middle of a coral ring.
- The depth of lagoon ranges between 40 to 70 fathoms.
Atolls are divided into
i. True Atoll: It is characterised by circular reef enclosing a shallow lagoon but without island.
ii. Island Atoll: having an island in the central part of the lagoon enclosed by circular reef
iii. Coral Island or Atoll Island: It does not have island in the beginning but later on island is formed due to erosion and deposition by marine waves.
- Atolls are found in Antilles Sea, Red Sea, China Sea, Australian Sea and Indonesian Sea.
- Shallow lagoon reefs are minor reef features which are annular in shape and are found in epicontinental seas like Indonesian Sea, South China Sea, etc.
- The lagoon is a small pool.
- Faros are chains of small atolls having shallow small lagoons.
- Coral banks are isolated shapeless reefs.
- Coral pinnacles are small ridges which rise within the lagoons.
18.4 CORAL REEFS IN INDIA
- Indian reef area is estimated to be 2,400 sq.km. The four major coral reef areas identified for intensive conservation and management are
- Gulf of Mannar b. Gulf of Kutch c. Lakshadweep d. Andaman & Nicobar
18.5 CORAL REEFS CONSERVATION
- The Ministry of Environment, Forests and Climate Change (MoEFCC) is the ministry responsible for the conservation and management of Coral Reefs in India.
- The emphasis is more on preventive aspects through monitoring and surveillance as the restoration work is both costly and time consuming.
- The ministry provides financial assistance to the state forest departments for all the four identified coral reef areas for activities like monitoring, Surveillance, education and awareness.
- The ministry also supports research and development activities with emphasis on targeted research on coral biodiversity, its management and various aspects of pollution in these areas.
18.6 CORAL BLEACHING
- Coral Bleaching is a process which causes loss of vivid colours from coral organisms and turns them white due to expulsion of symbiotic zooxanthellae algae which are embedded in the tissues of outer bodies of living corals (polyps). Mass coral bleaching causes mass coral deaths and destruction of living corals.
- Global warming has been reported as the major factor of coral bleaching.
- Coral bleaching can be classified into 4 types. They are
i. Catastrophic bleaching: adversely affecting 95% of shallow water corals in Bahrain, Maldives, Sri Lanka, Singapore and Tanzania
ii. Severe bleaching: accounting for 50-70% death of corals in Kenya, Seychelles, Japan, Thailand and Vietnam.
iii. Moderate bleaching: resulting into 20-50% coral mortality but with quick recovery.
iv. Insignificant bleaching or No bleaching.
CATASTROPHIC CORAL BLEACHING EVENT (1997-98) has been recorded as the most catastrophic event as it accounted for large scale of death of corals in the tropical oceans of 60 countries and island nations, 70% death of corals off the coasts of Kenya, Maldives, Andaman and Lakshadweep islands in the Indian ocean and 75% death in Marine Seychelles and Tanzania.
18.7 CORAL BLEACHING IN INDIA
- The cases of large scale coral bleaching have been reported in the Andaman & Nicobar islands of India.
- The areal coverage of coral reefs in India has been estimated to be 18,000 km2.
- The corals have mainly colonized by around the Lakshadweep and the Andaman & Nicobar Islands.
- Besides, small patches of coral reefs are found in the Gulf of Kutch and Gulf of Mannar.
- According to the study conducted by the Society for Andaman & Nicobar Ecology (SANE) based at Port Blair, there has been mass coral beaching (in 1998) around the Nicobar reefs. This bleaching is related to 2° C rise in temperature from normal temperature in the Andaman Sea.
- According to the study by National Institute of Oceanography (NIO) based at Goa, the coral reefs of the Kavaratti and Kadamat islands in Lakshadweep have suffered great damage from coral bleaching due to bacterial diseases and warmer sea temperature.
- The corals in the Gulf of Kutch have been bleached due to siltation.
18.8 CAUSES OF CORAL BLEACHING
- GLOBAL WARMING: Most of the scientists acknowledged global warming as the most significant factor of coral bleaching causing large scale coral death. According to Global Coral Reef Alliance (GCRA), every known mass bleaching occurred when temperature is 1°C higher than normal (warmest summer temperature).
- EL NINO: The warmest year 1998 resulted in mass coral bleaching was related to El Nino weather phenomenon. Coral bleaching of 1983, 1987 and 1998 was also associated with strong El-Nino weather phenomenon.
- CORAL DISEASES: The outbreaks of coral diseases like black band disease, coral plague, aspergillosis and white band disease cause coral death.
- LOCAL FACTORS: Local factors like siltation of sea water due to mass flux of sediments, pollution of sea waters caused by industrial effluents, urban sewage, destructive fishing practices, overfishing and mining of coral rocks results in coral degradation at local and regional levels.
18.9 RECOVERY NATURE OF CORAL REEFS
- Corals have recovery characteristics. Large scale climatic changes since Mesozoic era, fluctuations in solar activities and several environmental stresses corals have managed to survive and recover.
- It is to be noted that reefs will not become extinct in the long term, but a single bleaching event will take reefs between 30 to 100 years to recover.
- Proper research and studies on coral ecosystem is necessary to understand the corals and these studies should be applied to conserve the coral ecosystem from continued bleaching effects.
19. MARINE RESOURCES
- The biotic and abiotic resources found in the oceanic water and bottoms are called marine resources, which include marine water, inherent energy in the oceanic water (e.g. wave energy, tidal energy etc.), biotic life of marine water (plants and animals), marine deposits and abiotic elements (minerals, fossil fuels etc.), biotic and abiotic matter of ocean bottoms, benthic organisms, etc.
- Even a drop of oceanic water contains countless microscopic organisms.
- The marine resources are unique in the sense that they are renewable as most of the organisms can be regenerated.
- Man has been using oceans in a number of ways since long e.g., for transport, communication and trade, fishing, defense purposes, mineral extraction, recreation, medicines, waste disposal etc.
- Presently, the importance of oceans has increased many fold because of increased demand of food and minerals consequent upon ever increasing world population.
- Consequently, man, besides traditional ways of exploitations of marine resources, has become capable of modernizing traditional methods through his skill and advanced science and technologies. For example, the productivity and production of marine organisms (plants and animals) have been increased many fold through marine culture (mariculture), aquaculture, ocean ranching etc.
- There has begun a race for the exploitation of minerals associated with oceanic water, ocean deposits and ocean crusts, with the results the strategic importance of oceans has also increased accordingly.
- Many branches of knowledge of oceans have been developed for specific purposes e.g. marine geology, marine biology (for detailed study of marine organisms), economic oceanography (for the systematic study of marine resources), resource oceanography etc.
19.2 CLASSIFICATION OF MARINE RESOURCES:
Seas and oceans are endowed with different varieties of biotic and abiotic resources of two major sources.
- Firstly, rivers while draining through land areas of the lithosphere bring different types of materials into the seas. These materials contain mineral elements of different types, plants and animals.
- Secondly, some resources are manufactured by plants in shallow waters. It may be remembered that oceans are vast reservoirs of biotic resources. Nearly 40,000 species of molluscs and 25,000 species of fishes are found in marine waters.
- Besides mineral resources, different types of vitamins and medicinal elements are also found.
- Generally, marine resources are divided into three categories e.g. biotic resources, abiotic (mineral and energy) resources and commercial resources (navigation, aviation, trade and transport etc.).
19.2.1 Marine biological resources
(A) Food resources
- i. Animal resources (fishes, crabs, prawns, zoo planktons etc.)
- ii. Plant resources (phytoplanktons, sea grass etc.)
(B) Non – food resources
- i. Corals
Alternatively marine biological resources can also be divided into the following 3 categories.
(A) Plankton communities:
- i. Phytoplanktons
- ii. Zoo planktons
(B) Nekton communities:
- i. Pelagic fishes
- ii. Demersal fishes
(C) Benthos communities:
- i. Epibenthic community
- ii. Benthic organisms
- iii. Inflora and infauna
19.2.2 Marine mineral resources:
(A) On the basis of location
- i. Minerals of the continental shelf deposits
- ii. Minerals of the continental slope deposits
- iii. Minerals of the deep sea bottom desposits
(B) On the basis of nature:
- i. Metallic minerals
- ii. Fuel minerals (petroleum, natural gas)
- iii. Construction materials (gravels, sands etc.)
19.2.3 Energy resources:
(A) Conventional energy:
- i. Petroleum
- ii. Natural gas
(B) Non – conventional energy:
- i. Tidal energy
- ii. Wave energy
- iii. Biomass energy
4. Freshwater resources:
Manufactured water (transformation of saline sea water through the processes of desalinization into potable water)
MARINE BIOLOGICAL RESOURCES (MBR):
- The richness and reserves of marine biological resources (marine biomass) depend on the penetration of solar radiation (sun light) into seawater and efficiency of biological cycle.
- The marine biome is divided from upper surface downward on the basis of habitats of marine organisms into upper marine water surface zone, middle zone and lower deep sea zone.
- It may be mentioned that there is to and fro vertical movement of marine animals (i.e. upper surface to middle and deep sea areas and from below upward). Thus, there is transfer of nutrients from the upper surface downward.
- The upper surface is called photic layer (upto 200m depth) wherein one celled phytoplanktons grow through the process of photosynthesis. This upper or photic layer is also called as marine green pasture.
- This layer is succeeded below by dimly lighted zone and aphotic zone.
- The plant and animal communities of marine environment and the environment of their habitats are collectively called marine biome which is vertically divided into two types. 1. Pelagic biome and 2. Benthic biome.
- Marine organisms (plants and animals) are divided into 3 categories on the basis of their habitats
- 1. Planktons are floating and drifting micro plants and animals of photic zone. These are divided into phytoplanktons (plant planktons) and zooplanktons (animal planktons).
- 2. Nektons include algae, strong and powerful floating and swimming marine animals mainly fishes. These marine animals move in all the zones of the oceanic environments.
- 3. Benthos includes those plants (non – photosynthetic or non – phototrophs) and animals which live at the bottoms of the seas and oceans.
1. Plankton Community
- Plankton Community includes the groups of buoyant and floating marine plants and animals which live in the photic (euphotic zone or eupelagic zone) upto the depth of 200m from sea level.
- Plant planktons, called as phytoplanktons produce food through the process of photosynthesis with the help of sunlight, water and atmospheric carbon dioxide and thus they are primary producer green plants and are also called as autotrophs.
- Algae and diatoms are most important members of this community. This community grows so quickly that within a short span of time they cover very large area of sea surface. Such area of dense cover of algae and diatoms is called marine pasture.
- There is reproduction explosion in some of the red – grey microscopic plants. Consequently, extensive area of red – gray plants is developed. Such area is called as red tide.
- The size of zooplanktons ranges from one millimeter to several meters.
- Zooplanktons are of the three types. 1.herbivore zooplanktons, 2.carnivore zooplanktons, and 3.detrivore zooplanktons.
- In fact, zooplanktons act as a bridge between marine pastures of phytoplanktons of photic zone and the largest sea animals.
2. Nekton Community
- Nekton Community consists of swimming animals of various depths of the seas and oceans.
- Most of the animals of nekton group are vertebrates.
- Fishes of numerous species are most important members of this community. Sea fishes are divided into two groups viz. Pelagic fishes and demersal fishes.
- These fishes are main sources of marine biological resources.
- The swimmer marine mammals of nekton community are divided into two groups e.g. (i)those marine animals which live in waters as well as on lands such as seals, and (ii) the second category of swimming marine mammals includes those animals which spend their entire life in sea water such as whales.
3. Benthos Community
- Benthos Community includes all those plants, and animals which live on the sea bottoms right from the littoral marine biome to the open sea biome.
- The organisms of this community are characterized by large species diversity.
- The total known species of benthos animals represent 16 per cent of the total species of all the marine animals.
- Benthos organisms are divided into two categories on the basis of their habitats e.g.1.epiflora and epifauna, and 2. Inflora and infauna.
- Epiflora and eipfauna live on the surfaces of sea bottoms whereas infauna and inflora live in the detritus and are generally buried whether completely or partially in the ocean bottom deposits.
- Sea weeds, large algae, eelgrass and turtle grass are important benthos plants.
- Benthos animals mostly include several species of molluscs e.g. bivale mussels, oysters and cockles.
- Majority of the benthos animals are scavengers (e.g. shark, sable fish, hagfish, octopus, etc).
- The life of marine benthic animals living on the 1000 – 4000 m deep.sea bottom largely depends on the organic matter of the upper surface of sea water and remains of nekton animals.
On the basis of uses, marine food resources are divided into two types.
(i) Protein rich food resources for the use as food for human beings (e.g. fishes),
(ii) Animal feed for domesticated animals.
- The contribution of fishes in the world annual income from marine resources of all categories stands second (next to trade and transport).
- Use of sea fishes for meat eating (carnivore) people is very much beneficial because these contain plenty of protein and amino acids in right proportion, vitamin B12 and very little quantity of saturated fat and cholesterol and thus help in reducing high blood pressure and heart diseases.
- Most of the fishes are also used as animal feed.
The following are the main forms of fishing and fish farming:
Fishing refers to the direct catching of sea fishes through different means and methods. Sea fishes are grouped in different categories on different bases. On the basis of depth, these are grouped into two categories e.g.
- (i) Clupeoid which lives in the upper water surface e.g. herring, sardine, pilchard, shads, anchovy etc., and
- (ii) Gadoid, living in the deep sea mainly at the sea bottom, e.g. cod, haddack, hake etc.
The fishes of clupeiod family account for 45 per cent of the total world catch while gadoid family contributes 15 per cent. Flounders (small flat fishes) contribute15 per cent of total world catch. The remaining 25 per cent is contributed by tuna, IT ackeral etc. (7 per cent), and other types of flat fishes, rose fishes, sea perches, mullets, jacks etc.
On the basis of location sea fishes are grouped in 3 categories viz.
- (i) Pelagic fishes (e.g. mackerels, tunas, herrings, anchovies etc.);
- (ii) demersal fishes (e.g. cod, sole, haddock, halibut etc.); and
- (iii) anadromous or migratory fishes (e.g. salmons).
Fishing areas (fisheries) are divided in two categories on the basis of temperature of sea water e.g.
- (1) Cold water fisheries, which have already been developed since long, and
- (2)Tropical and subtropical fisheries, which have potential for further development.
- The tropical and subtropical fishing areas have high potential for extensive fish catch in future.
- In fact, fishing has been greatly developed in the northern hemisphere and the continental shelves of mid – latitude temperate seas have become the largest fishing grounds because of availability of plenty of important and specific species of fishes (like mackerels), relatively low content of oil and fat, large demand of fish as human food, modern and advanced techniques and related means for fishing, provision for canning and preservation of fishes etc.
- In the Pacific, Atlantic and Indian oceans, fishing regions account for 53, 40 and 5 per cent of world catch respectively.
- Besides, Mediterranean Sea contributes 2% share of total world catch.
- Among different species of fish, anchovy variety fish accounts for the largest share, followed by herring, Atlantic cod, Alaskan walleye pollock and South African pilchard.
FISHING IN INDIA Fishing has not been developed upto mark in India though its total coastlines run for a length of 7,517km and ideal platforms of continental shelves for fishing are spread over an area of 311,680 square account for 75 and 25 per cent of total annual fish catch has been estimated as 20 – 25 million metric tonnes but actual annual fish catch is less than one million metric tonnes due to a host of factors e.g. tropical climate; lack of ample number of bays, coves, estuaries, backwaters etc. along the coasts; herbivore attitude of majority of Indian population and related less demand of fish as human food; traditional old methods of fish catching and limited means; lack of modern techniques of canning and storage of fishes etc.
- Marine farming, also known as mariculture or marine culture includes the processes of increase of productivity and reproduction, breeding and production of certain sea animals by making them captive in certain localities of sea water, feeding then on additional nutrient feed and selling them in the market by man.
- Mariculture is a form of aquaculture, wherein certain young animals are kept captive in certain well marked localities of sea water for certain period of time when they are grew on additional feed and are finally sold out in the market.
- The following sea animals are used for rearing under the process of mariculture: oyster, mussels, scallops, shrimp, carp, salmon, trout, catfish, Asian milkfish, mullet, tuna etc.
- It may not be possible to meet the increased food demand in future exclusively from land resources and therefore it has become now necessary to focus attention towards marine food resources to increase the world supply of required amount of food to feed the teeming millions.
- The oyster rearing is most prevalent form of Mariculture.
- Lobsters are reared in the coastal areas of New England region while shrimps are culture in Gulf of Mexico.
- Prawn rearing has go momentum in the coastal waters of many countries. Prawn farming has proved success in India, Thailand and Philippines.
3. OCEAN RANCHING:
- Ocean ranching, also called as ocean husbandry, refers to taming and training of sea mammals (like porpoise, dolphin, whale etc.) in marine environment.
- A host of scientists are busy in active researches for the development of scientific techniques to tame and train wild sea mammals to be used for different purposes.
- Porpoises are being trained to obey the signals and directions given by remote control and to mimic human sounds.
- Dolphins are trained for the following purposes: to help divers, to carry and bring back tools for the repair of anchored ships, relief work etc.
- In some areas porpoises are being trained as aqua – cow – boys. Though the ocean ranching is in its initial stage but there are ample possibilities for its development in near future.
The catching of whale is called whaling.Generally, whales are divided into 2 categories Toothed whales and Toothless whales.
- (i)Toothed whales feed on fishes, squids and crustaceans. Sperm whale is the major species of this family and is found in tropical and temperate seas. It may be as large as 18m in length with average weight of 35 tonnes. Killer whale is the most dangerous species of toothed whales and feeds on seals, porpoises, penguins and other small whales.
- (ii)Toothless whales are generally called as baleen whale and comprise the species of blue whales, finback whales, humpback whales, gray whales, sei, minke etc. Blue whales are the largest of all the species of toothless whales and are on verge of extinction. Blue whales breed in subtropical seawater during winter and then migrate to polar areas during summer for feeding. Fishermen find this period as the most convenient for heir catching. Blue whales now need protection and conservation.
- Since beginning man used to hunt whales to get different materials from whales for various purposes e.g. meat and blubber for human food, oil for lighting and ambergris.
- The oil from sperm whales is used as lubricants in the factories and to prepare soaps and cosmetics.
- Meat of whales is also used as feed for other animals while whale bones are used to manufacture fertilizers.
- Whales have become endangered species because of the introduction of modern techniques of whaling like ‘steam whaler’, ‘pelagic whaling’ etc.
- A few species of whales, like large baleen whales, have been so massively killed that they are on the verge of extinction.
- Blue whales, humpback whales and grey whales have also been victim of massive over whaling.
- Attempts are being made at world level for haulting massive killing of whales and a few international regulations have been formulated for their conservation.
- The International Commission on Whaling (ICW) determines the limit of whale catch in terms of BWU (blue whale unit, one BHU = one blue whale, 2 fin whales, 2.5 humpback whales, or 6 sei whales) per year from time to time.
- A few countries have imposed self-restriction on whaling (e.g. USA, Great Britain, Norway, Netherlands) knows as whaling moratorium. Killing of mother whales with their calves has been banned.
Different metallic and non – metailic minerals of the seas are found in two forms e.g. (i) mixed with sea water in solution form, and (ii) mixed with ocean bottom deposits.
MINERALS DISSOLVED IN SEAWATER:
- Important minerals of this category are salt, bromine, magnesium, gold, zinc, uranium, thorium, etc.
- According to an estimate one cubic kilometer of seawater contains 41.25 million tonnes of solid materials in dissolved form.
- Nearly 85 per cent of salt dissolved in seawater is constituted by sodium and chlorine.
- The popular method of manufacturing of salt from seawater involves the processes of holding of seawater in the evaporation basins prepared in the coastal land areas and drying of water through solar heat.
- The crude salts, obtained through evaporation of water in sun light and precipitation of salt contents, are made for human use after these are further refined.
- About one third of total world salt is manufactured through evaporation method.
</div class=”inner-box”>SALT PRODUCTON IN INDIA: In India, salt is made from seawater along the coasts of Gujarat, Maharashtra and Tamil Nadu. Gujarat alone produces 50 per cent of total salt produced in India per year.
- Seawater is saline and hence it is refined and is transformed into freshwater into freshwater so as to make it potable water, which is called as manufactured water.
- There is increasing demand of manufactured water in the coastal countries of warm arid regions due to rapid rate of urbanization. Consequently, several techniques of desalinization have been developed.
- Minerals dissolved in seawater are separated through different methods and processes but the commercial value of such minerals depends on their refining cost and real market price. According to an estimate 4 grams of gold can obtain from every one million tonnes of seawater and it is also estimated that the total reserve of gold dissolved in seawater is 5 million tonnes.
- But it is not economical to obtain gold from seawater because it becomes difficult to get sufficient supply of undiluted seawater as many elements are mixed with seawater, and also the cost of pumping of seawater and chemical refining is very high.
MINERALS OF SEA DEPOSITS
- On the basis of sources and location minerals of sea deposits are divided into two categories viz. (1) minerals of surface deposits, which are further divided into 3 subcategories (i) minerals of continental shelves, (ii) minerals of deposits on continental slopes, and (iii) minerals of deep sea bottom deposits; (2) subsurface minerals.
(1) MINERALS OF DEPOSITS ON CONTINENTAL SHELVES AND SLOPES
include zircon, monazite, magnetite, gold placer, diamond, platinum, sulphur, phosphorite and several types of building materials (like sands, gravels, boulders etc.).
- Monazite reserves are found in the coastal areas of India, United States of America, Brazil, Sri Lanka, Australia and New Zealand. India has the largest reserve of monazite of the world (90 per cent) in the placer deposits of Kerala coast.
- About 29 per cent of rutile mineral of the world is found in Australian coast areas. Rutile is Titanium dioxide and is used for coating on welded rods.
- Magnetite is associated with volcanic rocks and thus these are found in those continental shelves and slopes which are characterized by volcanicity. Magnetites are, thus, found along the circum – pacific volcanic belt i.e. along the western coastal areas of North and South America and eastern coasts of Asia. Japan coastal areas are estimated to have a magnetite reserve of 36 million tonnes.
- Cassiterite is a type of tin which is separated due to weathering of granites. Maximum reserves of cassitierites are found in the coastal areas of Thailand, Malaysia and Indonesia.
- Gold deposits are found in the continental shelves of Alaska and Oregon (USA), Chile, South Africa and Australia but its extraction is commercially not beneficial because of extraction cost.
- Phosphorites are mixed with muds and sands of continental shelves and slopes and are found in nodule form. Phosphorites are used for the manufacturing of fertilizers. Their estimated world reserves are 50 million tonnes, which are found in the continental shelves of Mexico, Peru, Australia, Japan and South Africa and their extraction at commercial level has yet to be started.
(2) Minerals of Deep Ocean bottom deposits
- Manganese nodules are the most significant minerals to be found in the ocean bottom deposits.
- Pacific Ocean contains the largest deposit of manganese nodules upto the depth of 4,000 m and Blake plateau of Atlantic Ocean has the second largest deposits of manganese nodules.
- The manganese nodules comprise several minerals like nickel, copper, cobalt, lead, zinc, iron, silicon, but there is maximum percentage of iron and manganese.
- These are derived through two most prevalent techniques e.g. (i) air lift technique, and (ii) continuous bucket line system.
- Commercial mining of manganese nodules has not developed because of very high mining cost.
(3) Subsurface minerals
- Subsurface minerals are mostly found in the oceanic crusts of continental shelves and include mineral oil and natural gas.
- Many countries have already started commercial production of petroleum and natural gas. Mineral oil and natural gas together contribute 90 per cent of all marine mineral resources. Offshore oil fields have been developed in the continental shelves of Mexican gulf, Persian gulf, North Sea, North, Alaska, Mexico, South Californian coast, Arctic Sea, India, Brazil, Australia, Taiwan, Japan etc.,
- Besides, offshore oil fields are being developed in Indonesia, east Africa, north – West Africa, Tasmania, East Asia, etc.
- Reserves of offshore mineral oil have been explored in the offshore regions of Konkan coast (Maharashtra), Gujarat coast, Malabar and Coromandal coasts, Krishna – Cauvery delta coast, Sunderbans, etc. From the standpoint of production, three offshore oil fields of India are most significant e.g. Bombay High, Bassein and Alia bet.
- Bombay (Mumbai) High Offshore oil fields are located 176 km north – west of Mumbai and are spread over an area of 2,500 square kilometres. The estimated oil reserve is 200,000,000 tonnes. Production started in 1976 and oil is drilled from the depth of 1400m. Bassein offshore oilfields are located to the south of Mumbai High, the production of which may be more than Mumbai High oilfields if fully developed.
- Aliabet offshore oilfields are located 45km away from Bhavnagar in the Gulf of Khambat.
MARINE ENERGY RESOURCE:
- Ocean tides, sea waves and thermal variation between upper warm surface of sea and lower cold water mass etc. are main sources of generation of electricity.
- Tidal and wave energy has been developed in the coastal areas of some of the countries. The rise and fall of water during tides are used for electricity generation.
- Two favourable conditions are necessary for the development of tidal energy viz. large tidal range and narrow water passage having swift tidal currents.
- Thus, tidal electricity can be generated only in those coastal areas where these conditions are available. A minimum tidal range of 5m is a prerequisite condition for electricity generation
- Big power plants have been established in the Rance estuary of Brittany of France, at the Kislaya Guba in Marmansk of CIS (Commonwealth of Independent States), at Kandla in India etc.
- Sea waves carry enormous amount of energy but little efforts and progress have been made to develop wave energy due to cost factor.
- Three methods have been developed to generate electricity from sea waves e.g. (i) vertical displacement method, (ii) salter device, and (iii) dam atoll method.
- A pilot power plant to generate electricity from sea waves has been planned at Vizhinjham, Kerala.
19.2.4 VITAMINS AND DRUGS RESOURCES
- Marine pharmacologists are presently busy in researches to use marine organisms (plants and animals) for vitamins and medicines to cure different diseases.
- It may be pointed out that a distinct discipline of marine pharmacology has been developed. Marine pharmacologists are busy in investigating physiological, physical and chemical properties of marine organisms like crabs, sharks, cods etc.
- Shark oil and cod liver oil are already in use as energy tonics.
- Now cod liver oil is also available in capsule form
19.2.5 CONSERVATION OF MARINE RESOURCES:
It is beyond doubt that if the present rate of growth of world population continues, the demand for world supply of food would also increase proportionately in future, which cannot be met with land sources alone. Thus, one has to look towards marine food resources. It is evident that the pressure on marine resources would increase in future, therefore it is necessary to initiate necessary suitable steps for exploitation, utilization, conservation and preservation of marine resources. It is necessary to look into certain basic facts regarding natural resources before attempting measures of management of marine resources.
- 1. After land resources, marine resources are resource frontier for human community and therefore there are possibilities of their extensive exploitation and utilization in different forms.
- 2. The intensity and magnitude of exploitation of marine resources would increase under the pressure of ever increasing world population. Thus, there is a need for in depth study and understanding of abiotic and biotic aspects of marine environment.
- 3. Some of the marine biological resources (like fishes) are over exploited while abiotic (physical) resources (minerals, energy, building materials) still await their exploitation at commercial level.
- 4. Decrease in the abundance of fishes due to overfishing has been reported from different parts. This may lead to reduction in world production of fishes in future.
- 5. (v)There has been spatial difference in the development of different fishing areas due to dynamics of different species of fishes (movement of fishes for breeding, spawning, feeding in different areas).
- 6. Changes in marine biological environment due to overfishing.
- 7. Marine biological environment is adversely affected by the introduction of modern methods and equipment of fishing.
- 8. Fish production (catch) depends on the estimate and prediction of future demand of fish for human food and animal feed. Sometimes, the estimated and predicted future demand of fishes comes true while some times proves false.
- 9. It becomes difficult to find out total number and quantity of marine living organisms. The accurate estimate of the growth and mortality rate of marine organisms is a prerequisite condition to ensure their sustainable yield. There should also be accurate knowledge of their absolute quantity.
- 10. Marine organisms do not honour any artificial boundary fized by man because they freely move in different areas of seas both horizontally and vertically.
- 11. It becomes practically difficult to enforce any international regulation related to exploitation of marine resources. Thus, unregulated exploitation of marine resources generates more competitions and makes exploitation process more costly.
- 12. Successful fishing does not depend on the size of their (fishes) areas and richness of their reserves but depends on their concentration and abundance at a particular time in a specific area.
- 13. The knowledge of nature and dynamics of fishes is necessary for successful and profitable fishing.
19.2.6 Measures of Management:
The following points should also be taken care of for the efficient management of marine resources to get their continued and ensured sustainable yield, rational exploitation, optimum utilization, conservation and preservation (of rare species) of marine resources and pollution free marine environment.
The wise and rational exploitation and optimum utilization of marine resources involve following points:
- 1. There should be well regulated exploitation of marine resources. This requires the accurate knowledge of exact quantity of abiotic resources and process and rate of regeneration of biological (living, plants and animals) resources.
- 2. There should be efficient exploitation of marine resources. This requires the following – knowledge of absolute number of gross reserve of a specific species of fishes. This may be achieved through proper survey of fishing areas by applying ‘ecosounder technique’, by maintaining catch statistics, determination of their age on the basis of the study of ring growth on fish scales, mapping of breeding places of fishing and determination of their numbers etc.
- 3. Accurate estimate and prediction of future demand of fishes for human food and animal feed.
- 4. Proper arrangement of canning and refrigeration for storage of fishes.
- 5. Efficient methods and techniques of fishing.
It is necessary to make the present fishing areas more and more efficient and productive and to explore new areas for rational and proper exploitation and utilization of marine biological resources. Proper knowledge of potential reserve, possibilities of abundance, availability and renewal of marine mineral and fishes should be available. Concrete steps should be taken to develop and enrich mariculture (breeding and rearing of certain selected marine organism), ocean husbandry, marine pasture, taming and training of certain sea animals (like dolphin,porpoises, shark, etc) for the sustainable yield of marine resources.
20. MARINE POLLUTION
- Marine pollution occurs when harmful, or potentially harmful, effects result from the entry into the ocean of chemicals, particles, industrial, agricultural and residential waste, noise, or the spread of invasive organisms.
20.2 SOURCES OF MARINE POLLUTION
- 80% of marine pollution comes from land. Air pollution is also a contributing factor by carrying off pesticides or dirt into the ocean.
- Land and air pollution have proven to be harmful to marine life and its habitats.
- The pollution also comes from nonpoint sources such as agricultural runoff, wind-blown debris and dust.
- Nutrient pollution, a form of water pollution, refers to contamination by excessive inputs of nutrients. It is a primary cause of eutrophication of surface waters, in which excess nutrients, like nitrogen or phosphorus, stimulate algae growth.
- Many potentially toxic chemicals adhere to tiny particles which are then consumed by plankton and benthos animals, most of which are either deposit or filter feeders.
- Many particles combine chemically and deplete oxygen, causing estuaries to become anoxic.
- When pesticides are incorporated into the marine ecosystem, they quickly become absorbed into marine food webs.
- Once in the food webs, these pesticides can cause mutations, as well as diseases, which can be harmful to humans as well as the entire food web.
- Toxic metals can also be introduced into marine food webs. These can cause a change to tissue, biochemistry, behaviour, reproduction, and suppress growth in marine life.
- Also, many animal feeds have a high fish meal or fish hydrolysate content. In this way, marine toxins can be transferred to land animals, and appear later in meat and dairy products.
20.2.1 DIRECT DISCHARGE
- Pollutants enter rivers and the sea directly from urban sewerage and industrial waste discharges, sometimes in the form of hazardous and toxic wastes.
- Mining for Copper, Gold. etc., is another source of marine pollution.
- Most of the pollution is simply soil, which ends up in rivers flowing to the sea.
- However, some minerals discharged in the course of the mining can cause problems, such as Copper, which can disturb the development of coral polyps.
20.2.2 LAND RUNOFF
- Surface runoff from farming, as well as urban runoff and runoff from the construction of roads, buildings, ports, channels, and harbours, can carry soil and particles laden with carbon, nitrogen, phosphorus, and minerals.
- This nutrient-rich water causes the growth of algae and phytoplankton to thrive in coastal areas; known as algal blooms, which have the potential to create hypoxic conditions by using all available oxygen.
- Polluted runoff from roads and highways can be a significant source of water pollution in coastal areas.
- About 75% of the toxic chemicals that are carried by stormwater that runs off through roads and driveways, rooftops, yards and other developed land.
20.2.3 SHIP POLLUTION
- Ships can pollute waterways and oceans in many ways.
- Oil spills can have devastating effects. While being toxic to marine life, polycyclic aromatic hydrocarbons (PAHs), found in crude oil, are very difficult to clean up, and last for years in the sediment and marine environment.
20.2.4 ATMOSPHERIC POLLUTION
- Wind-blown dust and debris, including plastic bags, are blown seaward from landfills and other areas. E.g. Dust from the Sahara moving around the southern periphery of the subtropical ridge moves into the Caribbean and Florida during the warm season as the ridge builds and moves northward through the subtropical Atlantic.
- Climate change is raising ocean temperatures and raising levels of carbon dioxide in the atmosphere. These rising levels of carbon dioxide are acidifying the oceans.
- This, in turn, is altering aquatic ecosystems and modifying fish distributions, with impacts on the sustainability of fisheries and the livelihoods of the communities that depend on them.
- Healthy ocean ecosystems are also important for the mitigation of climate change.
20.2.5 DEEP SEA MINING
- Deep sea mining is a relatively new mineral retrieval process that takes place on the ocean floor.
- Ocean mining sites are usually around large areas of polymetallic nodules or active and extinct hydrothermal vents at about 1,400 – 3,700 meters below the ocean’s surface.
- The vents create sulphide deposits, which contain precious metals such as silver, gold, copper, manganese, cobalt, and zinc.
- The deposits are mined using either hydraulic pumps or bucket systems that take ore to the surface to be processed.
- As with all mining operations, deep sea mining raises questions about environmental damages to the surrounding areas.
20.3 OCEAN ACIDIFICATION
- Ocean acidification is the on-going decrease in the pH of the oceans, caused by the uptake of Carbon Dioxide (CO2) from the atmosphere.
- An estimated 30–40% of the carbon dioxide from human activity released into the atmosphere dissolves into oceans, rivers and lakes.
- Increasing acidity is thought to have a range of possibly harmful consequences, such as depressing metabolic rates and immune responses in some organisms, and causing coral bleaching.
- Coral bleaching
- Loss of productivity in plankton
- Less fishery production, adversely affects population of coastal regions
- Weakening of shells in marine animals
- Disturbance in marine food chain and productivity
20.4 OCEAN SALINISATION
- The warming climate is altering the saltiness of the world’s oceans.
- Records showed that the saltier parts of the ocean increased salinity or their salt content by 4% in the 50 years between 1950 and 2000 adversely affecting the marine organisms.
- Changes in salinity results in changes in density of oceans also.
20.5 POLLUTION CONTROL
Efforts should be made to keep the seas and oceans free from anthropogenic pollution for rich and healthy condition of marine environment and ecology.
The following are the major sources of marine pollution:
- 1. Discharge of waste water, sewage, and toxic chemicals from the urban areas and industrial establishment of coastal areas into the seas;
- 2. Dumping of urban and industrial garbage of coastal cities and industries into the seas;
- 3. Disposal of solid waste materials mainly plastics in the sea water;
- 4. Leakage of enormous quantity of mineral oil from oil tankers and spreading of oil slicks therefrom;
- 5. Pollutants from offshore oil wells (according to an estimate on an average about 241 million gallons of oil are leaked every year from oil tankers in the oceanic water);
- 6. Increase in the acidity of seawater due to increase in the concentration of carbon dioxide consequent upon rapid rate of deforestation;
- 7. Increase in the concentration of heavy metallic materials like lead, copper, zinc, chromium, nickel etc.from land areas brought by the wind;
- 8. Arrival of radioactive substances from nuclear plants, nuclear – powered ships and testing of nuclear weapons into seawater etc.
MARPOL 73/78 is the International Convention for the Prevention of Pollution from Ships, 1973 as modified by the Protocol of 1978. (“MARPOL” is short for marine pollution and 73/78 short for the years 1973 and 1978.)
- MARPOL 73/78 is one of the most important international marine environmental conventions.
- It was developed by the International Maritime Organization in an effort to minimize pollution of the oceans and seas, including dumping, oil and air pollution.
- The objective of this convention is to preserve the marine environment in an attempt to completely eliminate pollution by oil and other harmful substances and to minimize accidental spillage of such substances.
- It entered into force on 2 October 1983. As of 2015, 152 states, representing 99.2 per cent of the world’s shipping tonnage, are state parties to the convention.
- All ships flagged under countries that are signatories to MARPOL are subject to its requirements, regardless of where they sail and member nations are responsible for vessels registered under their respective nationalities
- MARPOL Annex I came into force on 2 October 1983 and deals with discharge of oil into the ocean environment.
- It incorporates the oil discharge criteria prescribed in the 1969 amendments to the 1954 Oil Pollution Convention.
- It specifies tanker design features that are intended to minimize oil discharge into the ocean during ship operations and in case of accidents.
- MARPOL Annex II came into force on 6 April 1987. It details the discharge criteria for the elimination of pollution by noxious liquid substances carried in large quantities.
- It divides substances into and introduces detailed operational standards and measures.
- The discharge of pollutants is allowed only to reception facilities with certain concentrations and conditions.
- No matter what, no discharge of residues containing pollutants is permitted within 12 miles of the nearest land. Stricter restrictions apply to “special areas”.
- MARPOL Annex III came into force on 7 July 1992. It contains general requirements for the standards on packing, marking, labeling, documentation, stowage, quantity limitations, exceptions and notifications for preventing pollution by noxious substances.
- The Annex is in line with the procedures detailed in the International Maritime Dangerous Goods (IMDG) Code, which has been expanded to include marine pollutants. The amendments entered into force on 1 January 1991.
- Marpol Annex IV came into force on 22 September 2003. It introduces requirements to control pollution of the sea by sewage from ships.
- MARPOL Annex V came into force on 31 December 1988. It specifies the distances from land in which materials may be disposed of and subdivides different types of garbage and marine debris.
- The requirements are much stricter in a number of “special areas” but perhaps the most prominent part of the Annex is the complete ban of dumping plastic into the ocean.
- MARPOL Annex VI came into force on 19 May 2005. It introduces requirements to regulate the air pollution being emitted by ships, including the emission of ozone-depleting substances, Nitrogen Oxides (NOx), Sulphur Oxides (SOx), Volatile Organic Compounds (VOCs) and shipboard incineration.
- It also establishes requirements for reception facilities for wastes from exhaust gas cleaning systems, incinerators, fuel oil quality, for off-shore platforms and drilling rigs and for the establishment of SOx Emission Control Ain reas (SECAs).
20.6.1 AMENDMENTS IN MARPOL
- MARPOL Annex VI amendments according with MEPC 176(58) came into force 1 July 2010.
- Amended Regulations 12 concerns control and record keeping of Ozone Depleting Substances.
- Amended Regulation 14 concerns mandatory fuel oil change over procedures for vessels entering or leaving SECA areas and sulphur limits.
20.8. IMPLEMENTATION AND ENFORCEMENT
- On January 1, 2015, maritime shipping levels became legally subject to new MARPOL directives because the SECA (Sulphur Emission Controlled Areas) zone increased in size.
- This larger SECA zone will include the North Sea, Scandinavia, and parts of the English Channel.
- This area is set to include all of the Republic of Ireland’s international waters in 2020 culminating in all of Western Europe’s subjection to the MARPOL directive.
- This has proven controversial for shipping and ferry operators across Europe.
20.7 IMPORTANCE OF CONSERVATION
- It is expected from the world community to initiate concrete and effective steps to keep the oceanic water free from pollution in the interest of both marine biological community and human community.
- If complete check on the discharge and disposal of pollutants of different sorts into seawater is not possible, minimum quantity of pollutants to be discharged should be determined and agreed upon.
- There are two formidable problems in the conservation of marine resources and equal right of all countries for their use; high mobility of marine organisms.
- It is necessary to formulate and enact international laws and to enforce them strictly for sustainable utilization of marine resources.
- Several attempts have been made in this regard and many laws have been formulated like law of high sea; laws related to piracy, trade of slaves, war etc.; law of continental shelves; law of exploitation of sea bottoms etc., but these laws are not enough for the desired purposes.
- There is need for effective laws related to the exploitation of deep sea resources, strategic and military uses of seas, scientific researches and international cooperation to make marine resources useful for world human community.
- There is earnest need for serious ecological researches for the understanding of marine biological processes (both chemical and physical). Further development of marine biology is required for the study of marine ecology.
- The endangered species of marine organisms mainly fishes, which are at the verge of extinction due to overfishing need immediate protection.
- For example, 8 species of whales which have become endangered
are facing extinction. Baleen whales are the most endangered species of whales.
- The number of blue whales and humpback whales has also fallen alarmingly due to modern and efficient methods of whaling.
- A few countries like U.K. Norway, Netherlands etc. have self-imposed moratorium for the protection of whales. International cooperation is the need of hour in this regard.
21. MARTIME ZONES
- Maritime zones have been divided from time to time into different zones on the basis of different purposes viz. Sovereignty, exploitation of marine resources, trade and transport, recreation, war practices etc. and a number of international laws have been enacted to give them legal recognition.
- The offshore areas of a country have been divided into 3 zones e.g. territorial sea, exclusive economic zone and high sea. Besides, a few more terms are in practice such as internal waters, marine belt, marginal sea, contiguous zone etc.
21.1.1 Territorial Sea
- The shore and coastlines of a coastal country are never straight rather are crenulated and indented.
- The imaginary line joining the land projecting towards the sea is called base line.
- Sea water lying between coastland and base line is called internal water which is never contiguous.
- The seaward water from the coastland of a nation is called territorial sea, the distance of which is measured from the base line generally upto 12 nautical miles towards the sea.
- In the beginning, the seaward limit of territorial sea was determined as 3 miles (4.8 km) but now generally the limit of territorial sea of different nations has been determined differently e.g. Latin American countries have determined the limit of their territorial sea as 320 km (200 miles) while the USA accepts 4.8 km (3 miles) as the seaward limit of the territorial Sea. Territorial sea has been variously named as marine belt, marginal sea etc.
- The coastal nation has the right of its sovereignty over its territorial sea and has the full and exclusive right of its use. No other country can enter the territorial sea of a country without the permission of the convened country.
- The continuous portion of the sea beyond the seaward limit of territorial sea upto a distance of 12 nautical miles is called contiguous zone in which the concerned coastal country commands limited exclusive rights.
- The seaward limit of the contiguous zone is 24 nautical miles from the base line. The concerned coastal nation has the rights of custom duties, fiscal, strategic, defence, immigration and sanitary regulations within the territorial sea and contiguous zone and also enjoys the right to punish the concerned parties for the infringement of these regulations.
21.1.2 Exclusive Economic Zone
- This zone extends upto a distance of 200 nautical miles from the base line.
- The concerned coastal state has the exclusive right of the survey, exploitation, conservation and management of mineral resources of ocean deposits, ocean floor (crust), marine water energy, water and marine organisms within this Exclusive Economic Zone (EEZ).
- No other country can venture in any economic activity (e.g. fishing, mining etc.) in this zone without the permission of the concerned coastal state but this zone is open for laying down submarine cables, navigation of ships, flying of aeroplanes for other states.
- Such rights are enjoyed by other states only outside the seaward limit of the territorial sea.
21.1.3 High Sea
- High Sea extends beyond the seaward limit of the exclusive economic zone and includes the vast oceanic areas.
- All the countries have equal rights of navigation, aviation, fishing, mining, laying down of submarine cables, scientific researches, exploration etc.
- The United Nations Convention on the Law of the Sea (UNCLOS), also called the Law of the Sea Convention or the Law of the Sea treaty is the international agreement that resulted from the third United Nations Conference on the Law of the Sea (UNCLOS III), which took place between 1973 and 1982.
- The Law of the Sea Convention defines the rights and responsibilities of nations with respect to their use of the world’s oceans, establishing guidelines for businesses, the environment, and the management of marine natural resources.
- UNCLOS came into force in 1994, a year after Guyana became the 60th nation to sign the treaty. As of January 2015, 166 countries and the European Union have joined in the Convention. However, it is uncertain as to what extent the Convention codifies customary international law.
- While the Secretary General of the United Nations receives instruments of ratification and accession and the UN provides support for meetings of states party to the Convention, the UN has no direct operational role in the implementation of the Convention.
- There is, however, a role played by organizations such as the International Maritime Organization, the International Whaling Commission and the International Seabed Authority (ISA).
A maritime boundary is a conceptual division of the Earth’s water surface areas using physiographic or geopolitical criteria. It usually includes areas of exclusive national rights over mineral and biological resources, encompassing maritime features, limits and zones.
UPSC PREVIOUS YEAR QUESTIONS
1. On the planet earth, most of the freshwater exists as ice caps and glaciers. Out of the remaining freshwater, the largest proportion
- (a) Is found in atmosphere as moisture and clouds
- (b) Is found in freshwater lakes and rivers
- (c) Exists as ground water
- (d) Exists as soil moisture
2. The most important fishing grounds of the world are found in the regions where
- (a) Warm and cold atmospheric currents meet.
- (b) Rivers drain out large amounts of fresh water into the sea.
- (c) Warm and cold oceanic currents meet.
- (d) Contiental shelf is undualing.
3. Consider the following factors:
- 1. Rotation of the Earth
- 2. Air pressure and wind
- 3. Density of ocean water
- 4. Revolution of the Earth
Which of the above factors influence the ocean currents?
- (a) 1 and 2only
- (b) 1,2 and 3 only
- (c) 1 and 4
- (d) 2, 3 and 4.
4. The acidification of oceans is increasing . why is this phenomenon a cause of concern ?
- 1. The growth and survival of calcareous phytoplankton will be adversely affected
- 2. The growth and survival of coral reefs will be adversely affected
- 3. The survival of some animals that have phytoplankton larvae will be adversely affected
- 4. The cloud seeding and formation of clouds will be adversely affected
Which of the statements are correct?
- (a) 1, 2 and 3 only
- (b) 2 only
- (c) 1 and 3 only
- (d) 1, 2, 3 and 4
5. What would happen if phytoplankton of an ocean is completely destroyed for some reason?
- 1. The ocean as a carbon sink would be adversely affected.
- 2. The food chains in the ocean would be adversely affected.
- 3. The density of ocean water would drastically decrease.
- (a) 1 and 2 only
- (b) 2 only
- (c) 3 only
- (d) 1, 2 and 3
6. Which of the following have coral reefs?
- 1. Andaman and Nicobar Islands
- 2. Gulf of Kachchh
- 3. Gulf of Mannar
- 4. Sunderbans
Select the correct answer using the codes given below:
- (a) 1, 2 and 3 only
- (b) 2 and 4 only
- (c) 1 and 3 only
- (d) 1, 2, 3 and 4
7. What explains the eastward flow of the equatorial counter-current?
- (a) The Earth’s rotation on its axis
- (b) Convergence of the two equatorial currents
- (c) Difference in salinity of water
- (d) Occurrence of the belt of calm near the equator
8. Tides occur in the oceans and seas due to which among the following?
- 1. Gravitational force of the Sun
- 2. Gravitational force of the Moon
- 3. Centrifugal force of the Earth
Select the correct answer using the code given below.
- (a) 1 only
- (b) 2 and 3 only
- (c) 1 and 3 only
- (d) 1, 2 and 3
9. La Nina is suspected to have caused recent floods in Australia. How is Law Nina Different from El Nino?
- 1. La Nina is characterized by unusually cold ocean temperature in equatorial Indian Ocean whereas El Nino is characterized by unusually warm ocean temperature in the equatorial Pacific Ocean.
- 2. El Nino has adverse effect on South-West monsoon of India, but La Nina has on effect on monsoon climate.
Which of the statements given above is/are correct?
- (a) 1 only
- (b) 2 only
- (c) Both 1 and 2
- (d) neither 1 nor 2
10. In the context of ecosystem productivity , marine upwelling zones are important as they increase the marine productivity by bring the
1. Decomposer microorganisms to the surface
2. Nutrients to the surface
3. Bottom dwelling organisms to the surface
Which of the statements given above is/are correct?
(a) 1 & 2 (b) 2 only
(c) 2 & 3 (d) 3 only
11. At one of the places in India, if you stand on the seashore and watch the sea, you will find that the sea water recedes from the shore line, twice a day, and you can actually walk on the sea floor when the water recedes. This unique phenomenon is seen at
(a) Bhavnagar (b) Bheemunipatnam (c) Chanidpur(d) Nagapattinam
1. (C) 2. (C) 3. (B) 4. (D) 5. (A)
6. (A) 7. (B) 8. (D) 9. (D) 10. (C)