Coral reefs

Coral reefs are among the most diverse and complex of all ecosystems; the most heavily utilised and economically valuable and among the most beautiful and fascinating. Coral reefs represent a critical resource for millions of people. For millennia coastal communities have relied on coral reefs as a source of food. Coral reefs have also provided sand for island beaches and offered protection from tides and tropical storm surges for those who have settled along the coasts of these islands. In more recent times, coral reefs have become one of the favourite destinations for millions. However, in recent decades, humans have also applied unprecedented levels of stress to coral reefs that are creating problems for their survival.

Picture courtesy of Topham.

109 countries have coral reefs along their coasts. In 90 of them, reefs are being damaged by cruise ship anchors and sewage, by tourists breaking off chunks of coral, and by commercial harvesting for sale to tourists. One study of a cruise ship anchor dropped in a coral reef for one day found an area about half the size of a football field completely destroyed, and half again as much covered by rubble that died later. It was estimated that coral recovery would take fifty years!

Most impacts to coral reefs occur through:

  • Dredging and the construction and operation of resorts, marinas, docks, piers, wharves, breakwaters and other physical structures which beyond the direct physical impact also create new current and wave regimes.
  • Increased sedimentation as a result of coastal and upland development, construction, roads (especially dirt roads in resorts and subdivisions) and deforestation. Sedimentation is one of the main reasons for reef degradation. Sediments block light from the reef below, preventing the growth or survival of corals. They also, once settled may smother them and prevent settlement of new recruits. In St Lucia, increased sedimentation from land clearing for construction of hotels and roads and artificial beach maintenance is one of the leading causes for coral reef destruction.
  • Unsustainable fishing practices. These have contributed to the overexploitation of species and the reduction in reef productivity.
  • Anchoring, which apart from initial impact may smash corals over large areas due to anchor dragging and chain sweeps.
  • Reef walking. Tourists and local people walking on reefs may kill coral and flatten the reef's matrix. Diver damage resulting from coral breakage or death from frequent handling is only a major problem on very popular dive sites.
  • The direct introduction of wastes, which bring an overload of nutrients to the reef 'eutrophication -, typically lead to complex community changes. Usually algae flourish and can overgrow and kill corals and/or prevent settlement of new larvae. Particle feeding organisms such as sponges may become more common.

Related Resources

Related News

No records found.

Related Events

No records found.

Related Books

No records found.

Related Multimedia

No records found.

Related Institution

No records found.

Related Projects

No records found.