Reef
From Open Encyclopedia
- For other uses of "Reef", see Reef (disambiguation).
In nautical parlance, a reef is a rock, sandbar, or other feature beneath the surface of the water, but shallow enough to be a hazard to ships (see also bar). Many reefs result from abiotic processes—deposition of sand, wave erosion planning down rock outcrops, and other natural processes—but the best-known reefs are those of tropical waters developed through biotic processes dominated by corals and calcareous algae.
Although "reefs" can be created artificially either by special construction or through deliberately sinking ships, these are not really reefs, as it is seldom the case that an artificial obstruction would be created that is a hazard to shipping. These are structures created to enhance physical complexity on generally featureless sand bottoms in order to attract a diverse assemblage of organsims, especially fishes. Thus, "artificial reef" is a misnomer, though firmly established as the term used for man-made underwater habitat structures.
Biotic reef types
There are a number of biotic reef types, including oyster reefs, but the most massive and widely distributed are tropical coral reefs. Although corals are major contributors to the framework and bulk material comprising a coral reef, the organisms most responsible for reef growth against the constant assault from ocean waves are calcarous algae, especially, although not entirely, species of coralline algae.
Geologic reef structures
Ancient reefs buried within stratigraphic sections are of considerable interest to geologists because they provide paleo-environmental information about the location in Earth's history. In addition, reef structures within a sequence of sedimentary rocks provide a discontinuity which may serve as a trap or conduit for fossil fuels or mineralizing fluids to form petroleum or ore deposits.
