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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. [1] Most coral reefs are built from stony corals, whose polyps cluster in groups.
Reefs were formed by corals living in shallow depths of water. Darwin's theory set out a sequence of coral reef formation around an extinct volcanic island, becoming an atoll as the island and ocean floor subsided. Courtesy of the US Geological Survey. When the Beagle set out in 1831, the formation of coral atolls was a scientific puzzle.
For example, birth rate, death rate, migration, and density-dependent predation indirectly alter the ecosystem state by changing population density (a state variable). Ecosystem parameters are quantities that are unresponsive (or respond very slowly) to feedbacks from the system (i.e., they are independent of system feedbacks).
This process can be entirely abiotic or facilitated by microorganisms, especially iron-oxidizing bacteria. The abiotic processes include the rusting of iron-bearing metals, where Fe 2+ is abiotically oxidized to Fe 3+ in the presence of oxygen, and the reduction of Fe 3+ to Fe 2+ by iron-sulfide minerals.
Reef types include fringing reefs, barrier reefs, and atolls. A fringing reef is a reef that is attached to an island. Whereas, a barrier reef forms a calcareous barrier around an island, resulting in a lagoon between the shore and the reef. Conversely, an atoll is a ring reef with no land present.
A reef is a ridge or shoal of rock, coral or similar relatively stable material, lying beneath the surface of a natural body of water. [55] Many reefs result from natural, abiotic processes but there are also reefs such as the coral reefs of tropical waters formed by biotic processes dominated by corals and coralline algae.
The three types of precipitation (abiotic, biotically induced and biotically controlled) cluster into three "carbonate factories". A carbonate factory is the ensemble of the sedimentary environment, the intervening organisms and the precipitation processes that lead to the formation of a carbonate platform. The differences between three ...
Ecosystem services delivered by epibenthic bivalve reefs. Reefs provide coastal protection through erosion control and shoreline stabilization, and modify the physical landscape by ecosystem engineering, thereby providing habitat for species by facilitative interactions with other habitats such as tidal flat benthic communities, seagrasses and ...