Coral - Wikipedia
Coral reefs are among the most biologically diverse regions on Earth. (The chemical name for limestone is calcium carbonate.) do not have a symbiotic relationship with the zooxanthellae, these species do not build reefs. Coral reefs are built by and made up of thousands of tiny animals—coral itself a hard, cup-shaped skeleton made of calcium carbonate (limestone). Several million zooxanthellae live and produce pigments in just one square inch of coral. Button that links to the Atmosphere page. Button that links to Coral reefs thrive in a very narrow range of temperatures. A sharp increase in.
Rapid burial under even a thin layer of sediment can kill a coral reef outright. By making bleaching events more common, global warming will probably make corals more vulnerable to these other forms of damage. There is scientific dispute over whether corals will be able to evolve some resistance to increasing temperature. According to the adaptive bleaching hypothesis, corals shift the type of zooxanthellae on which they depend when repeatedly exposed to bleaching, thus adapting to higher temperatures.
There is some evidence supporting this view. However, it is very uncertain whether, if such adaptation occurs, it could continue for more than a couple of degrees of warming in water temperature.
Although warming of the world's seas will make some presently cool regions suitable for coral, the area that will be made newly suitable for coral is forecast to be small compared to that which will be lost. The greatest threat to corals from climate change, most experts agree, is not warming but the increasing concentration of carbon dioxide CO2 in the atmosphere.
As ofthe oceans were absorbing about a third of all anthropogenic human-released CO2. This was changing the chemistry of the oceans and thus affecting the ability of various organisms to produce calcium carbonatewhich is the material not only of coral skeletons but of the shells of clams, whelks, mussels, and other shelly animals.
When a CO2 molecule dissolves in water, it combines with the water in such a way as to release hydrogen ions. The hydrogen ions make the water more acidic. Fewer carbonate ions CO can exist stably in acidic water. It is carbonate ions, along with calcium ions, that shelly organisms, including coral polyps, use to produce their calcium carbonate shells. Fewer carbonate ions makes shell-building more difficult. There are far more calcium ions than carbonate ions, so carbonate ions are what limit the ability of shelly organisms to make shells in today's oceans.
Over the last years, the average pH a measure of acidity of the ocean's waters has fallen by 0.
This change has reduced the number of carbonate ions available to shelly organisms. At a certain acidity, the concentration of carbonate ions falls so low that corals have difficulty making their skeletons at all; this concentration may occur if today's atmospheric concentration of CO2, about parts per million, rises to over parts per million. This much CO2 will probably exist in the atmosphere by the end of the twenty-first century.
Made by people or resulting from human activities. Usually used in the context of emissions that are produced as a result of human activities. Low tropical island, often roughly ring-shaped, formed by coral reefs growing on top of a subsiding island. The rocky base of the atoll may be hundreds of feet below present-day sea level. Atolls, like other low-lying islands, are threatened with submergence by rapid sea-level rise caused by anthropogenic climate change.
Decoloration or whitening of coral from the loss, temporary or permanent, of symbiotic algae zooxanthellae living in the coral. The algae give corals their living color and, through photosynthesis, supply most of their food needs.
Coral Polyps | Coral Reef Alliance
High sea surface temperatures can cause coral bleaching. Living organism that, as part of a colony, builds the rocky calcium carbonate CaCO3 skeleton that forms the physical structure of a coral reef.
A warming of the surface waters of the eastern equatorial Pacific that occurs at irregular intervals of 2 to 7 years, usually lasting 1 to 2 years. Along the west coast of South Americasoutherly winds promote the upwelling of cold, nutrient-rich water that sustains large fish populations, that sustain abundant sea birds, whose droppings support the fertilizer industry.
Near the end of each calendar year, a warm current of nutrient-poor tropical water replaces the cold, nutrient-rich surface water. In most years the warming lasts only a few weeks or a month, after which the weather patterns return to normal and fishing improves. World's largest coral reef system, located along the northeastern coast of Australia.
The reef system, which is approximately 1, mi 2, km long, contains 3, individual reefs and islands and is threatened by sea-level rise and ocean warming caused by anthropogenic climate change.
Climate change and coral bleaching
Measures the acidity of a solution. It is the negative log of the concentration of the hydrogen ions in a substance. Presence of moving mineral particles in rivers or streams. Faster-moving water can carry more sediment. Erosion increases sediment loading, limited by stream capacity for increased sediment loading. A relationship or pattern of exchange that is mutually beneficial to two or more creatures.
Algae are symbiotic with lichens and corals; intestinal bacteria are symbiotic with mammals. Algae that live in the tissues of coral polyps and, through photosynthesis, supply them with most of their food. The relationship is symbiotic, as the polyps supply the zooxanthellae with a hospitable environment. When water temperatures are too high, corals lose their zooxanthellae. If the loss is too pronounced for too long, the coral dies.
Primary Source Connection Human impact on Earth's coral reefs is substantial. Global climate change is likely to exacerbate coral disease and reef death worldwide, with a negative impact on marine species and human economies dependent on healthy reefs.
The following excerpt discusses the impacts of climate change on the health and development of coral reefs, highlighting problems such as bleaching and reef death. The Pew Center on Global Climate Change is a United States -based think-tank that gathers scientific and economic data to inform policymakers on global climate change issues. The report's authors are researchers in atmospheric and marine sciences.
Anatomy of Coral
The causes of this crisis are a complex mixture of direct human-imposed and climate-related stresses, and include factors such as outbreaks of disease, which have suspected but unproven connections to both human activities and climate factors. Byan estimated 11 percent of the world's reefs had been destroyed by human activity, and an additional 16 percent were extensively damaged in —98 by coral beaching. Widespread coral bleaching, unknown before the s, has brought recognition that reefs are threatened by global-scale climate factors as well as by more localized threats, and that different types of stress may interact in complex ways.
Although the crisis is widespread, individual reefs and even whole regions exhibit considerable variation in both health and responses to stress. The Caribbean region has been particularly hard-hit by problems, many of which are well-studied. Caribbean case studies and inter-ocean contrasts help to illustrate both the consistencies and the variations in coral reef responses to complex environmental changes.
Climate and Environmental Change Over the past one to two centuries, human population growth and development have greatly altered not only local environments, but also the global environment as a whole.
Major systematic changes include rising atmospheric concentrations of greenhouse gases GHGs that influence the earth's energy budget and climate. In addition, the global phosphorus and nitrogen cycles have accelerated because of artificial fertilizer use and massive changes in land usethe hydrologic cycle has been altered by river damming and water diversion as well as climate change, major natural ecosystems have been altered by fishing, forestry, and agriculture, and the ecological and biogeochemical implications of increased atmospheric CO2 levels go well beyond the effects on global temperature.
Because coral reefs occur near the junction of land, sea, and atmosphere, their natural habitats experience both the marine and terrestrial results of any climatic change and are vulnerable to human activities…. Climatic Change Stresses to Coral Reefs Global climate change imposes interactive chronic and acute stresses, occurring at scales ranging from global to local, on coral reef ecosystems…. Gas bubbles preserved in polar ice caps show that atmospheric CO2 concentrations over the pastyears have oscillated between about and parts per million volume, or ppmv; past temperature and sea-level variations mimic the CO2 fluctuations, with relatively constant minimum glacial period and maximum interglacial values.
Accompanying this CO2 increase is an observed increase in temperature, and a decrease in pH of the surface ocean. IPCC projections show an even greater departure from geologically recent climates by the end of the present century. Coral Bleaching The atmosphere and the ocean have warmed since the end of the 19th century and will continue to warm into the foreseeable future, largely as a result of increasing greenhouse gas concentrations.
There is nothing quite like it in size, rarity, complexity and beauty and it is one of the Seven Natural Wonders of the World. A coral reef is composed of calcium carbonate, or limestone. This is absorbed from the water by colonies of coral polyps and coralline algae.
Most the underlying foundation of the reef is dead, made up of layer upon layer of coral skeletons. The living reef is built over the top of this, by tiny coral polyps adding new limestone to the massive base structure.
The polyps make skeletons or corallites of calcium carbonate around themselves. The beautiful colour of corals comes from the colourful tentacles of the coral polyps and the zooxanthellae algae that live in the tissues of many species.
Phylum Cnidaria is further subdivided into three classes: Corals are an ancient group having a simple, radially-symmetrical body with a single opening that serves as both a mouth and anus.
The body is made up of two layers of cells, separated by a jelly-like layer with no internal organs. Corals possess specialised stinging cells called nematocysts on their retractable tentacles that are used to catch food. Colder climates tend to experience major oceanic upwelling which brings nutrients to the surface.
This helps the growth of plankton. Compared with these plankton-rich waters, tropical seas do not provide plentiful feeding grounds for small carnivores, such as coral polyps. For some time, people wondered how such small creatures could flourish and build up such spectacular reefs.
The mystery was solved when large numbers of microscopic algae were found living in their tissues. These algae, called zooxanthellae, live symbiotically within hermatypic corals.
Zooxanthellae absorb the nitrogen wastes produced by the coral.