TYPES OF CORAL REEFS Coral Atoll Fringing Reef Barrier Reef
CORAL ATOLL • Isolated ring shaped reef rising out of deep water.
FRINGING REEF • A shallow water feature found close to and parallel to the shore. • Buchanan (1974) maybe 0.5 to 2.5 km in width.
BARRIER REEF • Parallel to the coast but separated from it by a lagoon ( a shallow body of water separated from the sea by a narrow strip of land).
THREATS TO CORAL REEFS • Land –based threats • Marine activities • Worldwide threats
LAND BASED THREATS Human activity on land in coastal regions has altered the near shore environment, threatening the reef. Around islands such as Barbados, Jamaica, and Tobago reefs have been damaged by: • Too much fresh water : Coral polyps ( soft parts) need saline conditions. They do not grow where rivers bring fresh water into the sea (Estuary). One such place in Jamaica is Agualta Vale- St.Mary. Human activities increase the flow of fresh water after heavy rain, For example : when forest are cleared or land is used for urban development . 2. Too much sediments: Corals need sunlight and clear water. They may be smothered when mud and other sediment is washed into the sea, for example because of quarrying , construction of buildings or soil erosion.
MARINE ACTIVITIES Coral reefs can also be threatened by large and small- scale marine activities, such as: Fishing: A well-managed fishing industry need not hurt the marine environment. However, damage may be caused by anchors by over-fishing , or badly placed or discarded fish traps and nets. A few fishers have used bleach or explosives, which cause serious and lasting damage to the reef. Oil spills: Oil and other chemicals can cause permanent damage. Small and mid-scale spills have occurred many times in the caribbean. A large tanker may be 450 metres long and carries up to 500, 000 tonnes of oil, enough to pollute an entire coastline.
WORLDWIDE THREATS Coral reefs are also threatened by worldwide changes, which cannot be controlled within the region. Higher sea temperatures caused by global warming may bring ‘bleaching’ of reefs. Increased levels of carbon dioxide in sea water may slow coral growth , and may also make seawater slightly acidic.
PRESERVATION OF CORAL REEFS 1. Coastal management • Pollution control
COASTAL MANAGEMENT Partly because of the threat of beach erosion, the Barbados government set up a Coastal Zone Management Unit in 1983. Its work includes: • Studying the action of waves , tides, and long shore drift, and how these may affect the coastline; • Monitoring water quality, and the state of the offshore coral reefs; • Advising on shoreline protection and management.
POLLUTION CONTROL A wide range of measures is needed to help prevent further damage to the fringing reef and allow growing coral to recover. As an important part of its strategy, the government of Barbados Built a sewerage system on the south coast, which was completed in 2004. pipes were laid beneath the road to collect waste water from houses and business places. A treatment plant removes all solid waste material for safe disposal on land, and a pipeline takes the liquid waste 1,100 metres out to sea, where it is discharged in water which is 30-40 metres deep , beyond the fringing reef. From this point, the waste is rapidly dispersed by marine currents, and washed out to sea. The sewerage system reduced several problems: • Fresh water is discharged away from the shore. Near shore areas remain saline, allowing coral growth . • Sediment is not discharged into the sea. • Most organic material and some chemicals are removed at the treatment plant. Other chemicals are discharged in deep water, away from the growing coral.