Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.
The Great Barrier Reef is the world's largest coral reef system, composed of over 2,900 individual reefs and 900 islands stretching for over 2,300 kilometres (1,400 mi) over an area of approximately 344,400 square kilometres (133,000 sq mi). The reef is located in the Coral Sea, off the coast of Queensland, Australia, separated from the coast by a channel 100 miles wide in places and over 200 feet deep. The Great Barrier Reef can be seen from outer space and is the world's biggest single structure made by living organisms. This reef structure is composed of and built by billions of tiny organisms, known as coral polyps. It supports a wide diversity of life and was selected as a World Heritage Site in 1981. CNN labelled it one of the Seven Natural Wonders of the World in 1997. Australian World Heritage places included it in its list in 2007. The Queensland National Trust named it a state icon of Queensland in 2006.
A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups.
Coral bleaching is the process when corals become white due to various stressors, such as changes in temperature, light, or nutrients. Bleaching occurs when coral polyps expel the zooxanthellae that live inside their tissue, causing the coral to turn white. The zooxanthellae are photosynthetic, and as the water temperature rises, they begin to produce reactive oxygen species. This is toxic to the coral, so the coral expels the zooxanthellae. Since the zooxanthellae produce the majority of coral colouration, the coral tissue becomes transparent, revealing the coral skeleton made of calcium carbonate. Most bleached corals appear bright white, but some are blue, yellow, or pink due to pigment proteins in the coral.
Southeast Asian coral reefs have the highest levels of biodiversity for the world's marine ecosystems. They serve many functions, such as forming the livelihood for subsistence fishermen and even function as jewelry and construction materials. Corals inhabit coastal waters off of every continent except Antarctica, with an abundance of reefs residing along Southeast Asian coastline in several countries including Indonesia, the Philippines, and Thailand. Coral reefs are developed by the carbonate-based skeletons of a variety of animals and algae. Slowly and overtime, the reefs build up to the surface in oceans. Coral reefs are found in shallow, warm salt water. The sunlight filters through clear water and allows microscopic organisms to live and reproduce. Coral reefs are actually composed of tiny, fragile animals known as coral polyps. Coral reefs are significantly important because of the biodiversity. Although the number of fish are decreasing, the remaining coral reefs contain more unique sea creatures. The variety of species living on a coral reef is greater than anywhere else in the world. An estimation of 70-90% of fish caught are dependent on coral reefs in Southeast Asia and reefs support over 25% of all known marine species. However, those sensitive coral reefs are facing detrimental effects on them due to variety of factors: overfishing, sedimentation and pollution, bleaching, and even tourist-related damage.
The Great Barrier Reef is the world's largest reef systems, stretching along the East coast of Australia from the northern tip down at Cape York to the town of Bundaberg, is composed of roughly 2,900 individual reefs and 940 islands and cays that stretch for 2,300 kilometres (1,616 mi) and cover an area of approximately 344,400 square kilometres (133,000 sq mi). The reef is located in the Coral Sea, off the coast of Queensland in northeast Australia. A large part of the reef is protected by the Great Barrier Reef Marine Park.
Ove Hoegh-Guldberg, is a biologist and climate scientist specialising in coral reefs, in particular bleaching due to global warming and climate change. He has published over 500 journal articles and been cited over 50,000 times.
Nancy Knowlton is a coral reef biologist and a former Sant Chair for Marine Science at the Smithsonian National Museum of Natural History.
Human activities have significant impact on coral reefs. Coral reefs are dying around the world. Damaging activities include coral mining, pollution, overfishing, blast fishing, the digging of canals and access into islands and bays. Other threats include disease, destructive fishing practices and warming oceans. The ocean's role as a carbon dioxide sink, atmospheric changes, ultraviolet light, ocean acidification, viruses, impacts of dust storms carrying agents to far-flung reefs, pollutants, algal blooms are some of the factors that affect coral reefs. Evidently, coral reefs are threatened well beyond coastal areas. Climate change, such as global warming, causes a rise in ocean temperatures that lead to coral bleaching which can be fatal to the corals.
The hologenome theory of evolution recasts the individual animal or plant as a community or a "holobiont" – the host plus all of its symbiotic microbes. Consequently, the collective genomes of the holobiont form a "hologenome". Holobionts and hologenomes are structural entities that replace misnomers in the context of host-microbiota symbioses such as superorganism, organ, and metagenome. Variation in the hologenome may encode phenotypic plasticity of the holobiont and can be subject to evolutionary changes caused by selection and drift, if portions of the hologenome are transmitted between generations with reasonable fidelity. One of the important outcomes of recasting the individual as a holobiont subject to evolutionary forces is that genetic variation in the hologenome can be brought about by changes in the host genome and also by changes in the microbiome, including new acquisitions of microbes, horizontal gene transfers, and changes in microbial abundance within hosts. Although there is a rich literature on binary host–microbe symbioses, the hologenome concept distinguishes itself by including the vast symbiotic complexity inherent in many multicellular hosts. For recent literature on holobionts and hologenomes published in an open access platform, see the following reference.
A Mesophotic coral reef or mesophotic coral ecosystem (MCE), originally from the Latin word meso (meaning middle) and photic (meaning light), is characterised by the presence of both light-dependent coral and algae, and organisms that can be found in water with low light penetration. Mesophotic Coral Ecosystem (MCEs) is a new, widely-adopted term used to refer to mesophotic coral reefs, as opposed to other similar terms like "deep coral reef communities" and "twilight zone", since those terms sometimes are confused due to their unclear, interchangeable nature.
Ocean acidification threatens the Great Barrier Reef by reducing the viability and strength of coral reefs. The Great Barrier Reef, considered one of the seven natural wonders of the world and a biodiversity hotspot, is located in Australia. Similar to other coral reefs, it is experiencing degradation due to ocean acidification. Ocean acidification results from a rise in atmospheric carbon dioxide, which is taken up by the ocean. This process can increase sea surface temperature, decrease aragonite, and lower the pH of the ocean. The more humanity consumes fossil fuels, the more the ocean absorbs released CO₂, furthering ocean acidification.
Ruth Deborah Gates was the Director of the Hawaiʻi Institute of Marine Biology and the first woman to be President of the International Society for Reef Studies. Her research was dedicated to understanding coral reef ecosystems, specifically coral-algal symbiosis and the capacity for corals to acclimatize under future climate change conditions. Doctor Gates is most accredited with looking at coral biology and human-assisted coral evolution, known as super corals, as notably seen in the documentary Chasing Coral, available on Netflix.
A marine heatwave is a period of abnormally high ocean temperatures relative to the average seasonal temperature in a particular marine region. Marine heatwaves are caused by a variety of factors, including shorter term weather phenomena such as fronts, intraseasonal, annual, or decadal modes like El Niño events, and longer term changes like climate change. Marine heatwaves can lead to severe biodiversity changes such as coral bleaching, sea star wasting disease, harmful algal blooms, and mass mortality of benthic communities. Unlike heatwaves on land, marine heatwaves can extend for millions of square kilometers, persist for weeks to months or even years, and occur at subsurface levels.
All animals on Earth form associations with microorganisms, including protists, bacteria, archaea, fungi, and viruses. In the ocean, animal–microbial relationships were historically explored in single host–symbiont systems. However, new explorations into the diversity of marine microorganisms associating with diverse marine animal hosts is moving the field into studies that address interactions between the animal host and a more multi-member microbiome. The potential for microbiomes to influence the health, physiology, behavior, and ecology of marine animals could alter current understandings of how marine animals adapt to change, and especially the growing climate-related and anthropogenic-induced changes already impacting the ocean environment.
The island of Tobago has multiple coral reef ecosystems. The Buccoo Reef, the Culloden Reed and Speyside Reef are the three largest coral reef marine ecosystems in Tobago. The Buccoo Reef is a coralline reef ecosystem that is located on the southwestern region of Tobago. It is a popular ecotourism attraction where tourists can snorkel and see the coral reefs and schools of fish without diving equipment. The Trinidad and Tobago Tourism Ministry estimates that 90% of its tourists visit the Buccoo Reef while exploring Tobago. The Buccoo Reef, also known as the Buccoo Reef Complex, spans 7 km2 and has five reef flats that can reach up to 25 metres in depth. The reef complex has been designated as part of a protected Ramsar site since 2005.
Kimberly B. Ritchie is an American marine biologist. She is an Associate Professor in the Department of Natural Sciences at the University of South Carolina Beaufort. Her research is focused on marine microbiology and how microbes affect animal health in hosts such as corals and sharks.
Joan Ann ("Joanie") Kleypas is a marine scientist known for her work on the impact of ocean acidification and climate change on coral reefs, and for advancing solutions to environmental problems caused by climate change.
Janice Lough is a climate scientist at the Australian Institute of Marine Science (AIMS) at James Cook University, researching climate change, and impacts of temperature and elevated CO2 on coral reefs. She was elected to the Australian Academy of Science in 2022 for her research in climate change, coral reefs, and developing high resolution environmental and growth histories from corals, particularly the Great Barrier Reef.
Flinders Reef or Flinders Reefs is an isolated oceanic coral reef in the Coral Sea of the western Pacific Ocean. It lies east of Australia and the extensive Great Barrier Reef. Due to its remote location, it remains poorly studied. However, this isolation has also made it a potential site to mark the beginning of the Anthropocene.
