Coasts

Question 1

What is a coast?

Answer 1

Area where the land meets the sea

Question 2

Factors affecting coasts

Answer 2

Waves
Tides
Currents
Geology
Human Activities
Ecosystem Type

Question 3

Formation of waves

Answer 3

Waves form when energy from the wind blowing across the oceans and seas is transferred to the surface of the water.

Question 4

How do tides affect coasts?

Answer 4

Tides are the daily alternate rising and falling of the sea level, caused by the gravitational pull of the moon and sun on the earth. Each coastal area experienced two high tides and two low tides daily, which has significant impacts on the coast.
At high tides, waves erode and transport more sediments away from larger parts of the coasts than at other times.

Question 5

How do currents affect coasts?

Answer 5

Currents are large-scale continuous movement of water, driven largely by prevailing wind which generally blow in one direction.
Currents carry large amounts of energy and shape the coast through the processes of coastal erosion, sediment transport and sediment deposition.
Closer to the shore, nearshore currents help to shape the coastline. An example is the longshore currents which flow parallel to the coast.

Question 6

How do geology affect coast?

Answer 6

Geology is the arrangement and composition of rocks found in the area. Rocks may be arranged in layers such as alternate layers of hard and soft rocks. More resistant rocks such as basalt and granite erode slower than less resistant rocks such as limestone and shale. Coastal processes that operate on coasts consisting of different types of rock result in coasts with different coastlines.

Question 7

How do human activities affect the coast?

Answer 7

Examples of human activities are living, trading, fishing and engaging in recreational activities in these environments. People alter the coastline when they build marinas and port facilities. People also cause pollution in these environments by dumping waste into the water.

Question 8

How do the ecosystem type affects the coast?

Answer 8

In an ecosystem, plants and animals interact with one another as well as with their environments. The ecosystems of mangroves and coral reefs can reduce the impacts of waves on coasts. As a result, they affect the rate of change of coasts environments. The aerial roots of mangrove help trap sediments and reduce coastal erosion. The trapped sediments can form small islands and extend the coastline further seawards. Coral reefs are natural barriers that help reduce the speed and impact of waves on the coastline.

Question 9

Factors affecting waves

Answer 9

Wind Duration - The longer the wind blows, the larger the waves are, resulting in greater wave energy
Wind Speed - The faster the wind blows, the greater the wave energy is
Fetch - The greater the fetch is, the more energy the waves have as the wind would have passed through a larger body of water

Question 10

Characteristics of waves approaching coastlines from oceans

Answer 10

As a wave approaches shallow water near the coastline, it begins to change its shape at a depth which is half of their wavelength. The friction from the interaction with the seabed causes the base of the wave to slow down. However, the top of the wave does not slow down as quickly and causes the height of the wave to increase and wavelength to decrease as it moves into shallow water approaching the coast. Nearest the coastline, the base of the wave stops but the wave becomes steeper and topples over. When a wave curls over on itself onto the coast, it is called a breaker. When the wave breaks and runs up on the beach, it is called a swash. The swash loses energy due to gravity and friction with the land, it then retreats to the sea as backwash.

Question 11

Constructive waves

Answer 11

They are waves with low energy that are able to deposit materials on a coast. The waves have a strong swash and a weak backwash. Therefore, they break gently over a long distance. As swash is more powerful than backwash, they carry more sediments to deposit on the coast than remove them from the coast. Over time, the coast is built up by the deposited sediments to form sandy beaches with gentle slopes.

Question 12

Destructive waves

Answer 12

They are waves which break violently on the shore with high energy that can erode a coast. They are common along steep sloping coasts where they break with a great force over a short distance. The waves have a weak swash but a strong backwash, so more materials are removed than are deposited on the coast. Over time, the coast is eroded away.

Question 13

Wave refraction

Answer 13

It is the process by which the waves change direction as they approach an uneven coastline. The waves converge at headlands due to refraction with greater amount of energy, increasing wave height and erosive energy. This causes more erosion at the headlands. The waves diverge at bays due to refraction with less amount of energy, decreasing wave height and erosive energy. This allows more deposition to occur in bays.

Question 14

Coastal Processes

Answer 14

Hydraulic action
When the waves strike against a rock surface, the waves trap air in the rock joints. The air is compressed by oncoming waves, exerting a pressure on the joints. As the air is repeatedly compressed, the joints weaken and the rock shatters.
Abrasion
As waves break, sediments carried by the waves such as sand and rock are hurled against the coast. The loosened sediments knock and scrape against the coastal cliffs. This weaken the surface and break down the coast. Over time, the impact from abrasion is powerful enough to undercut a cliff.
Attrition
When rock particles carried by waves hit or rub against one another, they break down into smaller pieces and become smoother and more rounded over time.
Solution
Sea water reacts chemically with water-soluble minerals in coastal rocks and dissolves them. For example, limestone rocks are easily eroded by carbonic acid. When solution of minerals occurs, the rocks are weakened and eventually disintegrate.

Question 15

Sediment transport

Answer 15

This process involves moving materials along a coast by beach drift and longshore drift, resulting from the waves approaching the coast at an angle. As waves approaching the coast at an angle breaks on the beach, sediments move up the beach as swash and move perpendicularly down the beach as backwash. The resultant zig-zag movement along the beach is called the beach drift. When waves approach the coast at an angle, they generate longshore currents in the nearshore zone and transport sediments along the shore. Longshore currents are ocean currents that flow parallel to the coast. The combined effect of sediment movement caused by beach drift and longshore currents is known as the longshore drift.

Question 16

Sediment deposition

Answer 16

Sediments eroded from the coast are transported away and deposited elsewhere. When the wave energy decreases, the waves are unable to carry the sediments anymore. As such, larger sediments are deposited first, followed by smaller sediments. Deposited sediments vary in type and size, resulting in a variety of beaches. The location of the coasts affects the deposition of sediments. In areas where the coast is protected from the strong winds, destructive waves are less common. Hence, fine sediments are deposited along the coast with calm water such as the mangrove coasts in deep bays sheltered by headlands. On the other hand, coarser sediments are likely to settle in more exposed areas where there is higher wave energy to remove fine sediments.

Question 17

Formation of cliffs and shore platforms

Answer 17

The waves repeatedly pound against a rocky coast. This weakens the rocks and causes lines of weakness to form on the rock surface. Hydraulic action and abrasion may erode lines of weakness to form a notch. As erosion proceeds, the notch is deepened to form a bigger, hollow space called a cave. Further erosion by the waves will cause the roof of the cave to collapse, forming a steep cliff. As erosion continues, an overhanging cliff is formed. Eventually, the overhanging cliff collapses and materials will be deposited at the foot of the cliff. Some materials are carried by the waves and thrown against the base of the cliff, causing further erosion. Overtime, the cliff retreats inland and a gently sloping platform appears at the base of where the cliff used to be. The platform is a shore platform and it is submerged during high tides.

Question 18

Formation of bays and headlands

Answer 18

The coastline has bands of less resistant and more resistant rocks that alternate. The less resistant rocks erode faster than more resistant rocks. The less resistant rocks erode away to form wide indented coasts, called a bay. The more resistant rocks extend into the sea as they erode less, forming headlands.

Question 19

Formation of caves, arches and stacks

Answer 19

Within headlands, some rocks may be less resistant to erosion than other rocks. These parts of the headlands will be eroded more quickly, especially by hydraulic action and abrasion. Waves attack lines of weaknesses (such as joints & faults) at the base of the headland and undercut it. The continuous action of waves forms a cave at the area that is hollowed by the wave action. Caves may develop on each side of the headland. Erosion may eventually join caves together leaving a bridge of rock known as an arch above the opening. After a period of time, the roof of the area may collapse to form a stack. A stack is a pillar of rock in the sea left behind after an arch collapses.

Question 20

Characteristics of beaches

Answer 20

A beach is a zone of sediment deposition, usually formed from loose sand, gravel, pebbles, broken shells and corals, or a mixture of different materials. They may come from longshore drift, constructive waves, cliff erosion and river deposits. Changes in either wave energy or source of materials can affect the size of materials to change over time. Factors affecting slope of beaches is the grain size of sediments. Shape of beaches is affected by waves, tides and currents. For example, constructive waves help deposit beach materials and build up beaches further during calm weather. Destructive waves erode and remove beach materials during stormy weather.

Question 21

Formation of spits and tombolos

Answer 21

Some coasts will have an abrupt change in the direction of the coastline. Longshore drift continues to transport materials in the original direction for some time. Longshore drift deposits materials in the sea where they accumulate over time. The accumulated materials eventually appear above the water surface, forming a spit. A hook or curve may form at one end of the spit as wave refraction is concentrated at that point. When the spit extends further and connects an offshore island with the mainland or another island, it is a tombolo.

Question 22

Impacts of fisheries and aquaculture on the coastal environment

Answer 22

Fisheries are areas where fishes are farmed and bred to meet the increasing demand for fishes, while aquaculture refers to breeding fish in cages and ponds near coastal areas. For example, aquaculture is widely practiced in the world nowadays, including China, India, Vietnam and Thailand. In Vietnam, Ca Mau is an important shrimp production centre in the country. Nearly 60000 hectares of mangroves were cleared for building materials and land space in order to construct shrimp farms. Shrimp production was valued at about USD $800 million in 2010. This harms the coastal environment as the decrease in mangroves leave coastal areas vulnerable to coastal erosion, as there will no longer be mangrove roots to stabilise the coastline and anchor the soil.

Question 23

Impacts of housing and transportation on the coastal environment

Answer 23

People build houses on stilts above water and live in them. These stilt houses are joined by walkways to facilitate the movement of people within the community. People use boats as a common mode of transportation in coastal areas. For example, in Kukup, Malaysia, people depend on floating fish farms for their living and they sell fresh fish and other marine fish products such as salted fish and dried prawns at their farms. The local fishermen use boats to move around their fishing farms and tourists depend on the ferry services to visit Kukup island. This harms the coastal environment because the use of boats and presence of fish farms can result in more waste in the ocean waters, which can lead to water pollution and harm marine life. Trash washed up to the shore can also carry chemical pollutants and threaten physical habitats.

Question 24

Impacts of tourism and recreation on the coastal environment

Question 25

Coral reef ecosystems

Answer 25

They are structures found at or slightly below sea level on the seabed. They are built by tiny animals called coral polyps. These tiny animals secrete calcium carbonate as the protective layer of their soft and delicate bodies. When the coral polyps grow and die, new polyps grow on top of them. As a result, calcium carbonate skeletons accumulate as limestone and form giant coral reefs. They are found mainly between the Tropic of Cancer in the northern hemisphere and the Tropic of Capricorn in the southern hemisphere.

Question 26

Environmental conditions for coral reef growth

Answer 26

1. Sea surface temperature
   - should be between 17-18
2. Amount of sunlight received
   - availability of clear saline water between 10m and 60m deep allows sunlight to penetrate to promote algae photosynthesis
   - low turbidity of water allows enough sunlight to pass through
3. Level of salinity and oxygen content
   - Average seawater salinity is about 34-37 parts per thousand
   - moderate water motion ensures that corals receive enough oxygen
4. Sedimentation
   - low sedimentation so that living corals will not suffocate

Question 27

Value of coral reefs

Answer 27

They maintain natural ecosystem by supporting more than 25% of the earth’s marine fish species to breed and grow. They are a source of food and habitat for marine life that lives around the reefs. They can absorb wave energy that help protect the adjacent land mass from erosion. However, they have a slow recovery rate when they are damaged. Therefore, coasts are prone to erosion when coral reefs are damaged.

Question 28

Impact of overcollection on coral reefs

Answer 28

One pressure on coral reefs is the overcollection of corals. People collect corals excessively for personal or commercial use, such as using coral rubble as a building material for cement. An example of where this occurs is in the Philippines. This harms coral reefs as corals are weakened and the ecosystem is disrupted, hence leaving corals vulnerable to threats.

Question 29

Impact of fishing methods on corals

Answer 29

People practise destructive fishing methods such as dynamite blasting, the use of cyanide to stun fishes and spearfishing. For example, this practise occurs in the Philippines, Indonesia and the Netherlands. The use of dynamite and cyanide can destroy coral reef habitats. Spearfishing can reduce specific fish population and disrupt the food chain.

Question 30

Impact of climate change on corals

Answer 30

Climate change results in rapid changes in sea temperatures and sea levels. An example is in Seychelles. This pressure can cause coral bleaching due to the loss of algae in higher sea temperatures. The corals turn white completely or are bleached.

Question 31

Impact of recreational use of coast on corals

Answer 31

Development for tourism activities without careful planning such as the expansion of coastal resorts or the anchoring of boats can destroy coral reefs. For example, this happens in Sri Lanka. Recreational activities can result in water pollution when sewage waste is not properly managed or oil spills from boats. This will cause stress on corals. Boat anchors can destroy coral reefs.

Question 32

Impact of coastal development on corals

Answer 32

Coastal development such as land reclamation and expansion may dump rock and sand onto the reefs directly. Expansion of coastal resorts and residential areas can also cause a higher change of water pollution. Examples are in Japan and the USA. The coastal development may increase the amount of sediments in the water. The sediments can suffocate living corals.

Question 33

Characteristics of mangrove systems

Answer 33

Mangrove species are salt-tolerant tropical or subtropical plants which can grow in tidal mud on sheltered coasts. They have complex ecosystems by providing a habitat for their own as well as other plants and animals. Mangroves are a halophyte which means that they are capable of surviving in highly saline environment. They thrive on sheltered coasts and river estuaries with muddy and waterlogged land because these areas allow mud and plant litter to accumulate. They are found on the coasts located between the Tropic of Cancer and the Tropic of Capricorn.

Question 34

Adaptations of mangroves for survival

Answer 34

Prop Roots: Anchors the trees firmly in soft, muddy, ensuring that the tree will not be uprooted or swept away by the strong waves.

Aerial Roots: Has the same function as Prop Roots, as well as to take oxygen during parts of the day when they are not submerged.

Kneed Roots: To help trap soil between the roots, which is essential for plant growth.

Excess Salt Secretors: Secretes/excretes it through the underside of its leaves

Javelin-shaped fruits: To pierce the soft mud to germinate and grow into a sapling immediately

Bouyant Fruits: To allow it to float away and germinate in other coastal areas

Drip tips in Leaves: To allow rainwater to be drained easily so that the leaves stay light and do not decompose

Thick and leathery leaves: To reduce excess transpiration due to the Tropical Climate.

Colourful flowers: To attract insects to pollinate them

Question 35

Value of mangroves

Answer 35

have a dense network of roots which can stabilise shorelines by slowing down the flow of water through absorbing wave energy and by the building up of sediments amongst mangrove roots. both the dense network of roots and build-up sediments protect coastal areas from erosion by tides, waves, storms and tsunamis

mangrove habitats serve as a breeding ground and habitat for marine creatures e.g. oysters, barnacles, shrimps, crabs and certain fish species

Question 36

Impact of increasing demand for fuel wood and charcoal on mangroves

Answer 36

In places with low technology or low income economies, the local people tend to rely on mangroves as a source of fuel and charcoal. For example, this occurs in certain parts of Indonesia. The removal of mangrove forests reduces the breeding ground for fish. The coasts become more exposed to storm waves.

Question 37

Impact of coastal development on mangroves

Answer 37

People clear away mangroves to reclaim land for other developments such as housing, industrial and recreational use. An example is in the Caribbean Islands. Coastal development increases the likelihood of coastal water being polluted due to increasing human activities.

Question 38

Impact of conversion to other land uses on mangroves

Answer 38

People clear away large areas of flat and well-watered mangrove forests to set up paddy fields and shrimp farms. Examples are in Vietnam and Thailand. The disappearance of mangrove forests causes the coasts to be more vulnerable to erosion.

Question 39

Impact of rising sea level on mangroves

Answer 39

Climate change can cause sea level to rise quickly and also cause frequent extreme storm activities. For example, this occurs in the Gulf of Thailand. Mangroves cannot grow further inland despite the rise in sea level because they may be prevented by various human activities such as farming or installing sea defences.

Question 40

Effectiveness of limiting damaging activities to manage coastal areas

Answer 40

D: Damaging activities are activities that interrupt the functioning of natural systems. Some damaging activities include blasting coral reefs for coastal developments and clearing of mangroves to set up fish farms. As banning of these damaging activities might be costly and inefficient, many national and local government bodies instead try to limit these activities. This is done through management that aligns the needs and demands of people together with the nature of the coastal environment.

Ex: One example of how damaging activities can be limited is the management of sand dunes in Port Phillip, Melbourne. The sand dunes were often trampled on by visitors, destroying the dune vegetation and leaving the sand dunes exposed to wind erosion. Houses behind the dunes were in danger of being partly buried by the large volume of sand blown by the wind.

A: The authorities have built access paths for people to access the beaches and fenced off the dunes to allow the recovery of dunes.

L: However, the fences make the appearance of beaches to become less attractive and prevent the local people and visitors from accessing to all parts of the beach.

Question 41

Effectiveness of protecting coastal resources to manage coastal areas

Answer 41

D: Protecting coastal resources are able to prevent resources from being exploited or depleted completely. An example of coastal resource that needs to be protected is fish. Areas close to the coastline where 90% of all marine fish are caught are vulnerable to overfishing. This occurs especially in the coral reef areas of SEA where destructive fishing methods of blasting and poison fishing are used.

Ex: In Wakatobi National Park in Indonesia and the Goat Island Marine Reserve in New Zealand, the relevant authorities marked off certain zones to prevent commercial fishing activities. This measure is aimed to maintain ecosystems so that fish and endangered species can breed and thrive.

A: The GIMP has grown into a popular tourist destination due to its plentiful fish. There are up to 14 times more snappers within the reserve then outside it.

L: However, the establishment of marine reserves is often strongly opposed by local fishermen. This is because the fishermen see their access to a valuable resource, and possibly a major source of food, being denied. The potential long term benefits of a marine reserve may not be significant to locals who can no longer fish in an area that has supported them for a long time.

Question 42

Effectiveness of restricting development in areas prone to natural hazards to manage coastal areas

Answer 42

D: Many national governments and local authorities have developed management policies to deal with the threat of natural hazards in coastal areas. They research on how severe or widespread the problem is, plan for it, then make and enforce laws. The laws and policies usually involve a combination of retreat, avoidance, and defence. These protect both the coastal environment from damage and erosion by humans and also protect people from the natural hazards.

Ex: In USA, the Federal Emergency Management Agency (FEMA) steers development away form areas prone to flooding or coastal erosion.
[retreat] In Indonesia, the laws restrict new farms and houses from being established on low-lying coastal areas. [avoidance] In the Netherlands, beaches are monitored constantly and undergo nourishment when long-term erosion is identified.

A: By restricting development in areas prone to natural hazards near the coastline, there will be less destruction of property and infrastructure, as well as less loss of lives. with less human activities near the coastline, less erosion will occur on the beaches and less sand will be lost.

L: People may not comply with the laws and may continue to illegally build businesses and infrastructure near the coastlines. This may cause problems for the government in charge of regulating the coastlines. The businesses built near the coastlines may also cause damage to infrastructure and loss of lives.

Question 43

Effectiveness of seawalls

Answer 43

D: Seawalls are walls that are made of concrete or stone and constructed along and parallel to the coasts to reflect waves that hit against the seawall.

Ex: Vancouver seawall built around the perimeter of Stanley Park in Vancouver, British Columbia began in 1917 and extends 22km in total.

A: Seawalls protect coastlines against wave attack by absorbing wave energy.

L: Seawalls are costly to built and maintain as constant repairs may have to be made to prevent their collapse. They’re also only successful initially as backwash washes away the beach materials at the foot of and beneath the seawall, eventually undermining the base of the seawalls which lead to their collapse.

Question 44

Effectiveness of gabions

Answer 44

D: Gabions are wire cages usually filled with crushed rocks. These cages are built along a shore or behind a beach to prevent or reduce coastal erosions by weakening wave energy.

Ex: Gabions were installed when the East Coast Park in Singapore was first reclaimed. However, the gabions were subsequently removed as they were vandalised.

A: Gabions absorb wave energy better than seawalls. This is because the gaps between the rocks allow water to filter through, proving gabions to be successful defences against high energy waves.

L: However, the wire cages are unsightly and are costly as they need to be maintained regularly. They are also easily corroded by seawater and damaged by excessive trampling or vandalism

Question 45

Effectiveness of breakwaters

Answer 45

D: Breakwaters are structures built parallel to the coast or with one end attached to the coast, which help to break the force of oncoming waves.

Ex: In Almera, Spain, breakwaters are built offshore to break the force of oncoming waves. The land behind the breakwaters are protected from erosion caused by corrasion and hydraulic action. A zone of calm water is created behind them, where sediments are deposited to build up the beach.

A: When breakwaters are built offshore, they can break the force of oncoming waves and create a zone of calm water behind them, protecting the coast successfully. They also tend to prevent beach erosion for short-term periods. Materials are deposited and built up in the zone of calm water forming beaches.

L: However, Breakwaters are unsightly and costly to build and maintain and as such, developing countries may not be able to afford it. Breakwaters also protect the coast unevenly. Due to that, materials deposited in the zones behind breakwaters are protected but those located away from breakwaters maybe be subjected to wave action and erosion.

Question 46

Effectiveness of groynes

Answer 46

D: Groynes are low walls constructed at right angles to the shore to retain sediments that would otherwise be removed by longshore drift.

Ex: Groynes were built along Sandy Hook in New Jersey, USA. Groynes are perpendicular to the beach to trap sand flowing north towards Sandy Hook due to longshore currents.

A: It reduces the energy of waves and cause materials to be deposited on updrift side of the groyne facing the longshore drift. Hence, it is effective in maintaining a beach.

L: However, they are unsightly and expensive to build and maintain. No new materials deposited on downdrift side which is not protected by groynes. As a result, longshore drift will gradually erode away the unprotected part of the beach. To overcome this limitation, the tips of groynes are sometimes angled about 10*, depending on the direction of the prevailing winds, to prevent erosion on the downdrift side of groynes.

Question 47

Effectiveness of tetrapods

Answer 47

D: Tetrapods are four-pronged concrete structures that help dissipate wave energy. They are stacked offshore in an interlocking position.

Ex: Crescent City, town on the coast of northern California, has used tetrapods for many years to defend against coastal erosion and to reduce the impact of tsunamis, which occurred 31 times between 1933 and 2008.

A: Tetrapods allow water to pass around them instead of hitting against them, hence no powerful backwash is generated, reducing damage by waves. Tetrapods are pre-casted, so they can be used quickly to protect coasts from wave attack.

L: Tetrapods are aesthetically unappealing. They are also expensive to build so countries may not be able to afford. They can pose danger to swimmers and boaters due to its shape.

Question 48

Effectiveness of beach nourishment

Answer 48

D: Beach nourishment involves using sand from an external source to replenish the sand on a depleted beach . The external sources can be sand from other beaches or sand dredged from the sea floor. Hence, this measure helps slow down the erosion of beaches.

Ex: Beach nourishment restored the depleted beach at the coast of Cape May Point in New Jersey, USA, where sand from an external source is used to replenish the depleted beach. This measure was also carried out in Sentosa, Singapore, by using fine sand to replenish Silosa, Palawan and Tanjong beaches to make them more aesthetically appealing.

A: Beach nourishment can transform a coast into a wide sandy beach that provides immediate protection to the inland area.

L: However, it is time consuming and costly to truck and pipe in the sand. Many beach nourishment projects have also given rise to other problems. For example, the coral reefs at Waikiki Beach were destroyed because sand used for beach nourishment was washed out to the sea and suffocated the corals. Other management strategies are required to be put in place at the same time to prevent the re - nourished beaches from being eroded.

Question 49

Effectiveness of planting vegetation and stabilising dunes

Answer 49

D: Planting vegetation such as mangroves can stabilise coastlines, as mangroves can absorb wave energy through their dense root system. Sand dunes can be stabilised through planting grasses, which have roots that anchor the sand and prevent erosion.

Ex: Fences and an access path were built at the coast along Triton Place in Western Australia in order to protect the vegetated sand dunes.

A: Matting is often placed over the dunes to grow young grasses into the sand through the matting. When the grasses become mature and the dunes become more stable, the matting will rot away to add nutrients to the sand.

L - However, the vegetation take many years to grow before it can resist natural elements and human elements and are unable to protect immediate protection. It is also expensive to maintain the fences and paths to protect the sand dunes. The fences are also needed to be replaced at a suitable height once the sand accumulates to a new height over time.

Question 50

Effectiveness of encouraging coral reef growth

Answer 50

D: Coral reefs help to weaken wave energy and serve as a breeding ground and nursery for fish. Artificial reefs can be created by installing lasting materials, steel or concrete down the sea floor. These artificial reefs can attract corals and other marine life to colonise these materials and start to function as a natural reef.

Ex: Since 1996, the Maldives, which is a low-lying archipelago in the Indian Ocean, has been operating a coral-growing programme to help curb severe beach erosion on its many islands. A structure of welded construction steel rods, 45m long, 4 to 8m wide and 1.5m high, has been placed off the coast of one of its resort islands of Ihuru. The structure is charged with low-voltage solar-generated electricity to speed up coral growth.

A: The coral-growing programmes in the Maldives are successful and have received international recognitions as the corals are found to grow three to five times faster than normal. The island now has a wide variety of corals and marine creatures.

L: It is not easy to encourage the growth of corals. Sites need to be surveyed carefully to ensure maximum opportunity for growth. Coral growth may be slow, taking perhaps 20 to 30 years before results appear. Even then, coral growth may not be significant.