Importance of coral reefs to mankind & environment.
Forms of coral reefs.
Threats to coral reefs.
Dying coral reefs.
Conservation of reefs.
CORAL REEFS are the most diverse & beautiful of all the marine habitats . Coral reefs are the aragonite structures produced by living organisms, found in shallow, tropical marine waters with little to no nutrients in the waters.
ecosystem that is neglected more than any other and is also
one of the richest in biodiversity .
Reefs are useful to the environment and to
people in a number of ways. For example, they
Protect shores from the impact of waves and from storms
Provide a lot of benefits to humans in the form of food &
Provide economic benefits to local communities from
T he reef is topographically complex. Much like a rain forest, it has many strata and areas of strong shade, cast by the overtowering coral colonies. Because of the complexity, thousands of species of fish and invertebrates live in association with reefs, which are by far our richest marine habitats.
I n Caribbean reefs, for example, several hundred species of colonial invertebrates can be found living on the undersides of platy corals. It is not unusual for a reef to have several hundred species of snails, sixty species of corals, & several hundred species of fish. Of all ocean habitats, reefs seem to have the greatest development of complex symbiotic associations.
Fringing reef off the coast of Eliat, Israel. Coral reefs can take a variety of forms, defined in following; • APRON REEF – short reef resembling a fringing reef, but more sloped; extending out and downward from a point or peninsular shore. • FRINGING REEF – reef that is directly attached to a shore or borders it with an intervening shallow channel or lagoon. • BARRIER REEF – reef separated from a mainland or island shore by a deep lagoon; see Great Barrier Reef. • PATCH REEF – an isolated, often circular reef, usually within a lagoon or embayment. • RIBBON REEF – long, narrow, somewhat winding reef, usually associated with an atoll lagoon. • TABLE REEF – isolated reef, approaching an atoll type, but without a lagoon. • ATOLL REEF – a more or less circular or continuous barrier reef extending all the way around a lagoon without a central island; see atoll. • BANK REEF – Bank reefs are larger than patch reefs and are linear or semi-circular in outline.
Global Threats to Coral Reefs All around the world, much of the world's marine biodiversity face threats from activities and events such as • Coastal development; • Overfishing; • Inland pollution; • Global climate change. The 2004 edition of Status of Coral Reefs Around the World lists the following top 10 emerging threats in these three categories: Global Change Threats These are: • Coral bleaching - caused by elevated sea surface temperatures due to global climate change; • Rising levels of CO2 • Diseases, Plagues and Invasives - linked to human disturbances in the environment.
Direct Human Pressures These are: • Over-fishing (and global market pressures) - including the use of damaging practices (bomb and cyanide fishing); • Sediments - from poor land use, deforestation, and dredging; • Nutrients and Chemical pollution • Development of coastal areas - for urban, industrial, transport & tourism developments. The Human Dimension - Governance, Awareness & Political Will These are: • Rising poverty, increasing populations,alienation from the land • Poor capacity for management and lack of resources • Lack of Political Will, and Oceans Governance
Climate Change Impacts; The new emerging threat The above-mentioned Status of Coral Reefs Around the World,2004 says that “The major emerging threat to coral reefs in the last decade has been coral bleaching and mortality associated with global climate change.” It is believed that almost all species of corals were affected by high sea surface temperatures during 1998 which led to global coral bleaching and mortality.
Coral bleaching refers to the loss of color of corals due to stress-induced expulsion of symbiotic unicellular algae . The corals that form the structure of the great Reef e co systems of tropical seas depend on a symbiotic relationship with photosynthesizing unicellular algae called zoo xanthellae that live within their tissues. Zooxanthellae give coral its particular coloration, depending on the clade living within the coral.Under stress, corals may expel their zooxantheallae ,which leads to a lighter or completely white appearance , hence the term "bleached". CORAL BLEACHING
Coral bleaching is a vivid sign of corals responding to stress, which can be induced by any of: • Increased or reduced water temperatures (often attributed to global warming) • Solar Irradiance (photosynthetically active radiation and ultraviolet band light) • Changes in water chemistry (in particular ocean acidification) • Sedimentation (can be contributed to silt runoff) • Pathogen infections • Salinity High sea surface temperature (SST) coupled with high irradiance is known to be the primary factor in summer coral bleaching. Wind, exposure at low tide, & weather conditions can contribute to coral bleaching.
Once bleaching begins, Healthy corals tend to continue to bleach even if the stressor is removed. If the coral colony survives it often requires weeks to months for the remaining symbiont population to reach a normal density . Following bleaching, corals may be recolonised by the same species of zooxanthellae, or by a different species.Different types of zooxanthellae respond differently to environmental conditions & may be more resistant to coral bleaching than other species.
O ther coral reef provinces have been permanently damaged by warm sea temperatures, most severely in the Indian Ocean. Up to 90% of coral cover has been lost in the Maldives, Sri Lanka, Kenya and Tanzania and in the Seychelles. B ioerosion (coral damage) such as this may be caused by coral bleaching. Pathogen infection
Coral reefs are home to a variety of tropical or reef fish. Other fish groups found on coral reefs include groupers, snappers, grunts and wrasses. Over 4,000 species of fish inhabit coral reefs. Reefs are also home to a large variety of other organisms, including sponges, Cnidarians, worms, crustaceans ,molluscs, echinoderms & sea snakes. Aside from humans, mammals are rare on coral reefs, with visiting cetaceans such as dolphins being the main group. A few of these varied species feed directly on corals, while others graze on algae on the reef and participate in complex food webs.
A number of invertebrates, collectively called cryptofauna, inhabit the coral rock substrate itself, either boring into the limestone surface or living in pre-existing voids & crevices. Those animals boring into the rock include sponges, bivalve Molluscs ,& Sipunculans. Those settling on the reef include many other species, particularly crustaceans & Polychaete worms.
Local economies near major coral reefs benefit from an
abundance of fish and octopus as a food source .
Reefs also provide recreational scuba diving tourism.
Besides the recreational use, coral is also useful as a
protection against hurricanes & other extreme weather.
Red shades of coral are sometimes used as a gemstone,
especially in Tibet.
In vedic astrology, red coral represents Mars .
Pure red coral is known as 'fire coral' & is very rare because
of the demand for perfect fire coral in jewelry-making.
Ancient coral reefs on land are often mined for lime or use as
building blocks (" coral rag "), for example the
Portland limestone .
Coral Reefs Are DYING Around the World The Status of Coral Reefs Around the World, 04 notes that: • 20% of the world's coral reefs have been effectively destroyed and show no immediate prospects of recovery; • Approximately 40% of the 16% of the world's reefs that were seriously damaged in 1998 are either recovering well or have recovered; • The report predicts that 24% of the world's reefs are under imminent risk of collapse through human pressures; and a further 26% are under a longer term threat of collapse; A report from the World Resources Institute (WRI) in 1998 suggested that as much as 60 % of the earth's coral reefs are threatened by human activity. Scientists have said that as much as 95 % of Jamaica's reef are dying or dead.
It is estimated that about 60% of the world’s reefs are at
risk due to destructive, human-related activities.
In Southeast Asia, an Enormous 80% of reefs are considered
General estimates show approximately 10% of the coral
reefs around the world are already dead.
In 2000 found that only 6% of Indonesia’s coral reefs
are in excellent condition, while 24% are in good condition,
and approximately 70% are in poor to fair condition .
SEACOLOGY is the world's premier nonprofit, nongovernmental organization (NGO) with the sole & unique purpose of preserving the environments & cultures of islands throughout the globe. Inhabitants of Ahus Island, Manus Province, Papua New Guinea, have followed a generations-old practice of restricting fishing in six areas of their reef lagoon. While line fishing is permitted, net and spear fishing are restricted based on cultural traditions. The result is that both the biomass and individual fish sizes are significantly larger in these areas than in places where fishing is completely unrestricted. PRESERVATION & RESTORATION Photo of Ahus Island, Papua New Guinea
One method of coastal reef management that has become increasingly prominent is the implementation of Marine Protected Areas (MPAs). MPAs have been introduced in Southeast Asia and elsewhere around the world to attempt to promote responsible fishery management & habitat protection. Project AWARE Foundation is a non-profit, worldwide, organization dedicated to "Conserving underwater environments through education, advocacy and action." Aquatic World Awareness, Responsibility and Education
Reef Restoration Technology Low voltage electrical currents applied through seawater crystallizes dissolved minerals onto steel structures.The resultant white limestone is the same limestone that makes up natural coral reefs. Corals rapidly colonize & grow at extremely fast rates onto these coated structures. The change in the environment produced by electrical currents also accelerates formation & growth of both chemical limestone rock & the skeletons of corals & other shell-bearing organisms .