Erosion and Coral Reefs Coral reefs also benefit humans by protecting shorelines from the full onslaught of storm-driven waves. Humans, however, are responsible for causing severe damage to coral reefs. Reefs are often destroyed by collectors, who use coral to create jewelry, and fisherman, who use poison or dynamite to catch fish. Because corals need sunlight and sediment-free water to survive, water pollution poses a grave danger. Oil spills, the dumping of sewage wastes, and the runoff of soil and agricultural chemicals such as pesticides all threaten the delicately balanced ecosystem of coral reefs. Read more: Coral - humans, body, water, Earth, life, plants, form, animals, waves, surface, Biology of corals, Formation of coral reefs http://www.scienceclarified.com/Ci-Co/Coral.html#ixzz0dpBURpfC http://www.scienceclarified.com/CiCo/Coral.html
Monitoring Network, an international environmental monitoring organization, issued the report with data gathered from scientists around the globe. According to the report, the world has lost 27 percent of its coral reefs. Some of those reefs can never be recovered, while some could possibly come back. Most of the damaged reefs were found in the Persian Gulf, the Indian Ocean, the waters around Southeast and East Asia, and the Caribbean and adjacent Atlantic. The report pointed out that global warming was the biggest threat facing coral reefs, followed by water pollution, sediment from coastal development, and destructive fishing techniques (such as using dynamite and cyanide). If nothing is done to stop the destruction caused by humans, 60 percent of the world's coral reefs will disappear by 2030. http://www.scienceclarified.com/CiCo/Coral.html Healthy coral reefs have rough surfaces and complex structures that dissipate much of the force of incoming waves; this buffers shorelines from currents, waves, and storms, helping to prevent loss of life, property damage, and erosion. [a] Up to 90 percent of the energy from wind-generated waves is absorbed by reefs, based on the physical and ecological characteristics of the reef and the abundance of the adjacent seagrass and mangrove ecosystems. [b] In fact, coastlines protected by reefs are more stable, in terms of erosion, than those without. [c] Reefs are also a source of sand in natural beach replenishment. [d]
http://coralreef.noaa.gov/aboutcorals/values/coastalprotection/
Environmental threats Main article: Environmental threats to the Great Barrier Reef
Sea temperature and bleaching of the Great Barrier Reef
The most significant threat to the Great Barrier Reef is climate change.[49]
[50] Mass coral bleaching events due to rising ocean temperatures
occurred in the summers of 1998, 2002 and 2006,[51] and coral bleaching will likely become an annual occurrence.[52] Climate change has implications for other forms of life on the Great Barrier Reef as well - some fish's preferred temperature range lead them to seek new areas to live, thus causing chick mortality in seabirds that prey on the fish. Climate change will also affect the population and available habitat of sea turtles. [53]
Another key threat faced by the Great Barrier Reef is pollution and declining water quality. The rivers of north eastern Australia provide significant pollution of the Reef during tropical flood events with over 90% of this pollution being sourced from farms.[54] Farm run-off is polluted as a result of overgrazing and excessive fertiliser and pesticide use. Due to the range of human uses made of the water catchment area adjacent to the Great Barrier Reef, water quality has declined owing to the sediment and chemical runoff from farming, and to loss of coastal wetlands which are a natural filter.[55][56][57] It is thought that the mechanism behind poor water quality affecting the reefs is due to increased light and oxygen competition from algae.[58]
Crown-of-thorns starfish
The crown-of-thorns starfish is a coral reef predator which preys on coral polyps. Large outbreaks of these starfish can devastate reefs. In 2000, an outbreak contributed to a loss of 66% of live coral cover on sampled reefs in a study by the CRC Reefs Research Centre.[59] Outbreaks are believed to occur in natural cycles, exacerbated by poor water quality and overfishing of the starfish's predators.[59][60] The unsustainable overfishing of keystone species, such as the Giant Triton, can cause disruption to food chains vital to life on the reef. Fishing also impacts the reef through increased pollution from boats, by-catch of unwanted species (such as dolphins and turtles) and reef habitat destruction from trawling, anchors and nets.[61] As of the middle of 2004,
approximately one-third of the Great Barrier Reef Marine Park is protected from species removal of any kind, including fishing, without written permission.[62] Other threats to the Great Barrier Reef include shipping accidents, oil spills, and tropical cyclones.[63] Skeletal Eroding Band, a disease of bony corals caused by the protozoan Halofolliculina corallasia, affects 31 species of corals from six families on the reef.[64] http://en.wikipedia.org/wiki/Great_Barrier_Reef#Environmental_threatsÂ
Coral reefs, with their vast diversity of invertebrate, vertebrate and algal species, have undoubtedly been subjected to natural disturbance since their appearance millions of years ago. Anthropogenic disturbance has been a factor affecting reefs for a fraction of that time, yet in terms of overall impact, may be of greater concern. Data on habitat destruction, pesticide and heavy metal accumulation, nutrient loading, sedimentation, runoff and related impacts of man's activities indicate that many coastal reefs are endangered by these processes through alterations in animalalgal symbioses, shifts in competitive interactions, direct mortality, reproductive failure, and insufficient recruitment. The death of corals critically affects reef communities, as corals provide an important trophic link as well as the main habitat structure. While natural disturbance is an important factor affecting reef interactions, species diversity and evolution, chronic anthropogenic disturbances combined with unsuitable environments for recovery, are of great concern. Physiological stress can be measured in corals in addition to outright mortality, allowing the impacts of specific disturbances to be assessed. Sufficientdata for distinguishing real problems from temporal variability are becoming available, allowing scientists to focus on practical solutions to problems in coral reef management and preservation. http://icb.oxfordjournals.org/cgi/content/abstract/33/6/524
a reef whose surface lies above the hightide mark, either by uplift or by eustatic regression of the sea (which is determined by ice sheet–sea level relations), is subject to planing by marine erosion. If planing off is complete, a flattopped submerged platform results. If subsidence or eustatic submergence intervenes, a wavecut terrace is left around the reef. http://www.britannica.com/facts/5/540904/erosionasdiscussedincoralreefgeology Carbon emissions are undermining coral reefs' ability to repair themselves. They need calcium carbonate to mend holes created by sea creatures and erosion, but the more C[O.sub.2] there is in the atmosphere, the more it's absorbed by the sea, which lowers the water's pH and reduces levels of dissolved calcium carbonate. Scientists believe that before the Industrial Revolution, more than 98 per cent of corals lived in water with enough calcium carbonate. Now, nearly half live in areas with dangerously low levels of the compound. http://findarticles.com/p/articles/mi_hb3120/is_11_80/ai_n31011424/?tag=content;col1 A study published in this week's issue of PNAS has shown that coral reefs in the waters off Panama and Galapagos, which live in a naturally acidic and high CO2 environment, contain dangerously low percentages of scement to hold them in place. The researchers believe that these reefs are a vision into the future of reefs worldwide, since their environment replicates the expected increased in acidity and CO2. Oceans have already absorbed about one-third of all carbon dioxide released into the atmosphere since the industrial revolution.
http://news.mongabay.com/2008/0728hance_reefs.html this link had even more helpful information