Corals are colonial 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.
Coral bleaching is the process when corals become white due to loss of symbiotic algae and photosynthetic pigments. This loss of pigment can be caused by 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.
White band disease is a coral disease that affects acroporid corals and is distinguishable by the white band of exposed coral skeleton that it forms. The disease completely destroys the coral tissue of Caribbean acroporid corals, specifically elkhorn coral and staghorn coral. The disease exhibits a pronounced division between the remaining coral tissue and the exposed coral skeleton. These symptoms are similar to white plague, except that white band disease is only found on acroporid corals, and white plague has not been found on any acroporid corals. It is part of a class of similar disease known as "white syndromes", many of which may be linked to species of Vibrio bacteria. While the pathogen for this disease has not been identified, Vibrio carchariae may be one of its factors. The degradation of coral tissue usually begins at the base of the coral, working its way up to the branch tips, but it can begin in the middle of a branch.
Black band disease is a coral disease in which corals develop a black band. It is characterized by complete tissue degradation due to a pathogenic microbial consortium. The mat is present between apparently healthy coral tissue and freshly exposed coral skeleton.
The Staghorn coral is a branching, stony coral, within the Order Scleractinia. It is characterized by thick, upright branches which can grow in excess of 2 meters in height and resemble the antlers of a stag, hence the name, Staghorn. It grows within various areas of a reef but is most commonly found within shallow fore and back reefs, as well as patch reefs, where water depths rarely exceed 20 meters. Staghorn corals can exhibit very fast growth, adding up to 5 cm in new skeleton for every 1 cm of existing skeleton each year, making them one of the fastest growing fringe coral species in the Western Atlantic. Due to this fast growth, Acropora cervicornis, serve as one of the most important reef building corals, functioning as marine nurseries for juvenile fish, buffer zones for erosion and storms, and center points of biodiversity in the Western Atlantic.
Elkhorn coral is an important reef-building coral in the Caribbean. The species has a complex structure with many branches which resemble that of elk antlers; hence, the common name. The branching structure creates habitat and shelter for many other reef species. Elkhorn coral is known to grow quickly with an average growth rate of 5 to 10 cm per year. They can reproduce both sexually and asexually, though asexual reproduction is much more common and occurs through a process called fragmentation.
White pox disease, first noted in 1996 on coral reefs near the Florida keys, is a coral disease affecting Elkhorn coral throughout the Caribbean. It causes irregular white patches or blotches on the coral that result from the loss of coral tissue. These patches distinguish white pox disease from white band disease which produces a distinctive white band where the coral skeleton has been denuded. The blotches caused by this disease are also clearly differentiated from coral bleaching and scars caused by coral-eating snails. It is very contagious, spreading to nearby coral.
Coral reef protection is the process of modifying human activities to avoid damage to healthy coral reefs and to help damaged reefs recover. The key strategies used in reef protection include defining measurable goals and introducing active management and community involvement to reduce stressors that damage reef health. One management technique is to create Marine Protected Areas (MPAs) that directly limit human activities such as fishing.
Human activities have substantial impact on coral reefs, contributing to their worldwide decline.[1] Damaging activities encompass coral mining, pollution, overfishing, blast fishing, as well as the excavation of canals and access points to islands and bays. Additional threats comprise disease, destructive fishing practices, and the warming of oceans.[2] Furthermore, the ocean's function as a carbon dioxide sink, alterations in the atmosphere, ultraviolet light, ocean acidification, viral infections, the repercussions of dust storms transporting agents to distant reefs, pollutants, and algal blooms represent some of the factors exerting influence on coral reefs. Importantly, the jeopardy faced by coral reefs extends far beyond coastal regions. The ramifications of climate change, notably global warming, induce an elevation in ocean temperatures that triggers coral bleaching—a potentially lethal phenomenon for coral ecosystems.
Pavona duerdeni, the porkchop coral, is a coral that forms clusters of cream-colored lobes or discs. They grow in large colonies, divided into ridges or hillocks. The coral is considered to be uncommon due to its low confirmed abundance, yet they are more commonly found in Hawaii, the Indo-Pacific, and the Tropical Eastern Pacific. They make up some of the largest colonies of corals, and have a slow growth rate, as indicated by their dense skeletons. Their smooth appearance is due to their small corallites growing on their surface.
Coral aquaculture, also known as coral farming or coral gardening, is the cultivation of corals for commercial purposes or coral reef restoration. Aquaculture is showing promise as a tool for restoring coral reefs, which are dying off around the world. The process protects young corals while they are most at risk of dying. Small corals are propagated in nurseries and then replanted on the reef.
The resilience of coral reefs is the biological ability of coral reefs to recover from natural and anthropogenic disturbances such as storms and bleaching episodes. Resilience refers to the ability of biological or social systems to overcome pressures and stresses by maintaining key functions through resisting or adapting to change. Reef resistance measures how well coral reefs tolerate changes in ocean chemistry, sea level, and sea surface temperature. Reef resistance and resilience are important factors in coral reef recovery from the effects of ocean acidification. Natural reef resilience can be used as a recovery model for coral reefs and an opportunity for management in marine protected areas (MPAs).
Galaxea fascicularis is a species of colonial stony coral in the family Euphylliidae, commonly known as Octopus coral, Fluorescence grass coral, and Galaxy coral among various vernacular names.
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 characterized by the presence of both light-dependent coral and algae, and organisms that can be found in water with low light penetration. Mesophotic coral ecosystems occur at depths beyond those typically associated with coral reefs as the mesophotic ranges from brightly lit to some areas where light does not reach. 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. Many species of fish and corals are endemic to the MCEs making these ecosystems a crucial component in maintaining global diversity. Recently, there has been increased focus on the MCEs as these reefs are a crucial part of the coral reef systems serving as a potential refuge area for shallow coral reef taxa such as coral and sponges. Advances in recent technologies such as remotely operated underwater vehicles (ROVs) and autonomous underwater vehicles (AUVs) have enabled humans to conduct further research on these ecosystems and monitor these marine environments.
Hologenomics is the omics study of hologenomes. A hologenome is the whole set of genomes of a holobiont, an organism together with all co-habitating microbes, other life forms, and viruses. While the term hologenome originated from the hologenome theory of evolution, which postulates that natural selection occurs on the holobiont level, hologenomics uses an integrative framework to investigate interactions between the host and its associated species. Examples include gut microbe or viral genomes linked to human or animal genomes for host-microbe interaction research. Hologenomics approaches have also been used to explain genetic diversity in the microbial communities of marine sponges.
Stony coral tissue loss disease (SCTLD) is a disease of corals that first appeared off the southeast coast of Florida in 2014. It originally was described as white plague disease. By 2019 it had spread along the Florida Keys and had appeared elsewhere in the Caribbean Sea. The disease destroys the soft tissue of at least 22 species of reef-building corals, killing them within weeks or months of becoming infected. The causal agent is unknown but is suspected to be either a bacterium or a virus with a bacterium playing a secondary role. The degree of susceptibility of a coral, the symptoms, and the rate of progression of the disease vary between species. Due to its rapid spread, high mortality rate, and lack of subsidence, it has been regarded as the deadliest coral disease ever recorded, with wide-ranging implications for the biodiversity of Caribbean coral reefs.
The environmental impact of recreational diving is the effects of recreational scuba diving on the underwater environment, which is largely the effects of diving tourism on the marine environment. It is not uncommon for highly trafficked dive destinations to have more adverse effects with visible signs of diving's negative impacts due in large part to divers who have not been trained to sufficient competence in the skills required for the local environment, an inadequate pre-dive orientation, or lack of a basic understanding of biodiversity and the delicate balance of aquatic ecosystems. There may also be indirect positive effects as the environment is recognised by the local communities to be worth more in good condition than degraded by inappropriate use, and conservation efforts get support from dive communities who promote environmental awareness, and teach low impact diving and the importance of respecting marine life. There are also global coral reef monitoring networks in place which include local volunteer divers assisting in the collection of data for scientific monitoring of coral reef systems, which may eventually have a net positive impact on the environment.
Jamaica, an island located within the Caribbean Sea, known for being a popular tourist destination because of its pristine white sand beaches, is now faced with the issue of mass coral depletion. Both environmental and human factors contribute to the destruction of these corals, which inevitably affect Jamaica's environmental sustainability and economy. Actions have been put in place to counteract the negative consequences associated with the loss of the corals, which act as a symbol of hope for the revival of Jamaica's environment.
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.
