Coral Reefs

Topic :Coral Reefs
Grade 10 subject: Geography

Table of Contexts

What is a Coral Reef?

Where are they located?

Types of coral reefs

Other types of coral reefs

Man’s impact on the coral reef

Rehabilitation of Coral Reefs

Bibliography

What is a Coral reef?

Coral reefs are underwater structures made from calcium carbonate secreted by corals. Coral reefs are colonies of tiny animals found in marine waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups.
Most coral reefs were formed after the last glacial period when melting ice caused the sea level to rise and flood the continental shelves.

Where are they located?

Coral reefs normally live in tropical regions (these regions include the tropical Pacific, tropical western Atlantic (Caribbean), and the Indian Ocean (including the Red Sea). Some reefs live in places that are cool, but never cold areas. One very popular reef is the Great Barrier Reef. It is off the northern coast of Australia. This reef grows in waters ranging from about 60-80 degrees Fahrenheit. There are also coral reefs in Mexico, Cuba, Florida, California, Hawaii, and Japan. A reef cannot withstand temperatures below 40 degrees Fahrenheit because the fish cannot live there. It's like a food chain.

Types of coral reefs
The three main types of coral reefs are:
(1) Atoll – this is a roughly circular (annular) oceanic reef system surrounding a central lagoon

(2) Fringing Reef - a reef system that grows fairly close to (or directly from) the shore, with an entirely shallow lagoon or an intervening shallow channel.

(3) Barrier Reef – is a reef system that parallels the shore and is separated from it by a wide lagoon that is very deep. Other reefs include

Patch reef – this type is an isolated, comparatively small reef outcrop, usually within a lagoon or embayment, often circular and surrounded by sand or sea grass. Patch reefs are common.
Apron reef – a short reef resembling a fringing reef, but more sloped; extending out and downward from a point or peninsular shore
Bank reef – a linear or semicircular shaped-outline, larger than a patch reef
Ribbon reef – a long, narrow, possibly winding reef, usually associated with an atoll lagoon
Table reef – an isolated reef, approaching an atoll type, but without a lagoon
Habili – this is a reef in the Red Sea that does not reach the surface near enough to cause visible surf, although it may be a hazard to ships

Man’s impact on the coral reef

Overfishing
Reefs are suffering directly and indirectly from the increasing pressure of mans' resource exploitation. Overfishing is one driving pressure that has had devastating impacts on coral reefs. Aggressive fishing methods have hurt coral reefs sometimes beyond repair. However, over-fishing in general is also a damaging problem to many coral reefs around the world. Specifically to the Great Barrier Reef, overfishing has caused a shift in the reef ecosystem. Overfishing of certain species near coral reefs can easily affect the reef's ecological balance and biodiversity.

Pollution
Another significant impact humans have had on the coral reef ecosystems is its pollution problem. There are numerous ways humans have added harmful pollutants into our oceans that can cause serious damage to the fragile ecosystems of the coral reefs. Deforestation, although not directly involved in coral reef destruction, has many indirect effects that cause many issues. Sediment runoff will bring with it many natural and toxic components that can cause harm to the coral ecosystems. There is also sedimentation buildup that occurs at the mouth of the rivers that lead into the oceans. Another major pollutant is runoff from mining and farming where the minerals get into rivers that flow into the ocean. Farming has specific negative effects with this type of pollution because of the nutrient runoff from the fertilizers used. These fertilizers add nitrogen and phosphorous into the oceanic ecosystem. These nutrients cause massive algae growth that leads to depletion in oxygen available for other creatures and decreasing the biodiversity in those affected areas. It also leads to algae blooms that take over sections of coral, blocking the sunlight and hurting its ability to survive. The coral reefs also have a hard time surviving through human pollution by petroleum leaks and other chemicals that get dumped into the oceans because of its toxicity the environment.

Blast fishing
Researchers believe that destructive fishing practices like blast fishing to be one of the biggest threats to the coral reef ecosystems. Blown up coral reefs are no more than rubble fields. The long-term impact associated with blast fishing is that there is no natural recovery of the reefs. Coral reefs are less likely to recover from constant disturbance such as blast fishing than from small disturbance that does not change the physical environment. Blast fishing destroys the calcium carbonate coral skeletons and is one of the continual disruptions of coral reefs. As a result, weakened rubble fields are formed and fish habitat is reduced.

Marine debris
Marine debris is any solid object that enters coastal and ocean waters. Debris may arrive directly from a ship or indirectly when washed out to sea via rivers, streams, and storm drains. Human-made items tend to be the most harmful such as plastics (from bags to balloons, hard hats to fishing line), glass, metal, rubber (millions of tires!), and even entire vessels.
Plastic debris kills several reef species. Derelict (abandoned) fishing nets and other gear often called "ghost nets" because they still catch fish and other marine life despite being abandoned can entangle and kill reef organisms and break or damage reefs. Even remote reef systems suffer the effects of marine debris.

Rehabilitation of Coral Reefs

REMOVING NEGATIVE IMPACTS

This should always be the first priority, as it will encourage natural recovery. More active techniques for reducing stresses include removing ‘pest’ or predatory species, such as sea urchins or crown of thorns starfish.

INCREASING SUBSTRATE FOR SETTLEMENT

On a damaged reef, the availability of suitable substrate for larval settlement can rapidly decrease due to algal or soft coral overgrowth, and sedimentation. Minimizing land based sources of nutrient enrichment and maintaining algae-eating fish populations will help to reduce algae. Artificial reefs may have an additional benefit for fisheries management but the cost may be prohibitive for large areas.

Encouraging natural surfaces - This can be done by stabilizing or removing loose substrate material (such as coral fragments) and removing algae and other organisms that might inhibit larval settlement or damage young recruits.

Creating new surfaces through electrolysis - This technique is not recommended, but has been tested in some countries. Electrical currents are passed through a conductive material, such as chicken wire, causing calcium and magnesium minerals to precipitate from seawater to form a limestone framework. This requires considerable financial and human investment and a source of permanent electrical current while the structure is being built. The long-term impact of the electrical current on marine life is not known.

TRANSPLANTING CORALS

Coral fragments or colonies can be removed from a reef and transplanted to natural substrate on a damaged reef, or to artificial substrates such as concrete blocks. Many species survive transplantation provided environmental factors are favorable, but it is expensive in terms of labour, unless volunteers can be used. Also transplanted fragments are highly vulnerable to dislodgement by waves and human disturbance, and are easily buried or smothered. The source of corals for transplantation must be chosen with care, to avoid damage to other reefs.

FARMING CORALS

Attempts have been made to farm corals. Coral fragments are transplanted to a protected site and ‘grown out’ to a certain size before being used for rehabilitation and for creating new fragments. The source of fragments must be chosen with care, to avoid damage to other reefs. Coral farms potentially have an additional benefit as an attraction for snorkelers. Further investigation is required to reduce costs and increase success rates.

Bibliography

reefrelief.org/learn/coral-reef-ecosystem

en.wikipedia.org/wiki/Coral_reef‎

life.bio.sunysb.edu/marinebio/coralreef.html

www.globalissues.org/article/173

Protection of corals
Both national and state governments have regulated fishing, license collectors, outlaw some fishing practices, and set up protected reserves. Also, coral reef parks prohibit fishing and collecting.
Healthy coral reefs can be affected by scuba divers. It is a popular hobby. When coral reefs are stood upon or sometimes even touched, they are damaged and have a slow recovery. They are very fragile and might die. Marine biologists report seeing some dead coral in the shape of diver’s fins, which are used for swimming.
Boats hurt the coral reefs, too. More specifically, the boats anchor. When an anchor drops in a coral reef, a quarter of the corals’ growth is ruined. If the anchor is dragged, it could ruin about half of the reef. In order to prevent anchor problems, permanent mooring buoys are put in so boats don’t need anchors. People can be fined for harming coral. Many people are learning to scuba dive, and that diving around coral is a special responsibility.

How do humans affect coral reefs?
We shouldn’t destroy reefs. Some people don’t even realize what they are doing. Others don’t care. Overfishing in coral reef areas can do plenty of damage. It may sound surprising if your not a fisherman. Humans (especially fisherman) use spear guns, which can damage the coral. Or they might use commercial poisons. Sometimes, even dynamite. Besides what fisherman use, the actual overfishing can damage too. How? It can damage food chains around and in the coral reefs. Well, sea urchins, little spiky animals, can overwhelm the coral reef. Humans fish for the predators of sea urchins, such as porcupine fish, a lot! So much, that the predators of the sea urchins are very rare in those areas. The point is that sea urchins can ruin the coral reefs. Sea urchins eat kill reefs. Used-to-be-reefs become so covered with algae that animals cannot build new colonies for them to live in.
The top concern for the coral reefs is the condition and quality of the water that the coral is growing in. When humans pollute the water, there is great danger for the coral. They could have coral bleaching. Coral bleaching is when large areas of coral turn white. The polyps let out microscopic algae from the cells in their bodies. It then shows the white limestone skeletons that the polyps have. Coral bleaching happens when they are under stress. An alga is what they eat, and without it they don’t get enough food. This leads to the point where the polyps can’t grow or reproduce. If nothing is fixed, corals die. The possible cause of coral bleaching is pollution, hurricane damage, disease, etc. Some scientists are beginning to think that global warming is another cause. Others do not agree because coral reefs are full of stress from lots of sources. In usual conditions, coral reefs could resume normal life after a hurricane or other stressful damaging things. But, coral bleaching all over the reef is not normal. Scientists learned this by studying ancient coral deposits. The effect coral bleaching has if it continues to spread all over our coral reefs is that coral will die. That would be a terrible loss to lose one of the most wonderful things in the world.
Some people like to have in their homes a thing called a mini reef. It is the fastest growing product of the aquarium industry. A mini reef is a saltwater aquarium full of reef life. Of course, that comes from real reefs. More than half of the reef animals in human homes are captured in the wild. A lot of the animals die when being transported to their destination. Others die after a few weeks or months in the aquariums. One reason they die is because divers stun the fish by spraying sodium cyanide into hiding places of the fish. Sodium cyanide is poison that damages corals and the organs of the fish. According to research, 70% of all reef life caught die during that year. Several of which cannot survive away from the actual reef anyway! That includes cleaner fish and butterfly fish, which both die of starvation.