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Types of Coral Reefs
NOAA Image
Fringing reefs are coral reefs that grow in shallow waters and border the
coast closely or are separated from it by a narrow stretch of water. Fringing
reefs consist of several zones that are characterized by their depth, the
structure of the reef, and its plant and animal communities.
These regions
include the reef crest (the part of the reef the waves break over), the fore
reef (the region of medium energy), and the spur and groove or buttress zone
(the region of coral growth which includes rows of corals with sandy canyons or
passages between each row).
Fringing
Reef Bora Bora NASA JPL Satellite: Space Shuttle Sensor: SIR-C/X-SAR
Apron
reef – short reef resembling a
fringing reef, but more sloped; extending out and downward from a point or
peninsular shore
Barrier reefs are reefs that are separated from land by a lagoon. These reefs
grow parallel to the coast and are large and continuous. Barrier reefs also
include regions of coral formation that include the zones found in fringing
reefs along with patch reefs (small reefs), back reefs (the shoreward side of
the reef), as well as bank reefs (reefs that occur on deep bottom
irregularities).
Barrier reefs also include reef flats (the are of the reef not
exposed), the reef crest, which runs parallel to the coast and is protected from
waves, and a coral terrace (a slope of sand with isolated coral peaks). These
features are followed by another coral terrace and a vertical drop into deeper
waters.
Australia’s
Great Barrier Reef
NASA/GSFC/LaRC/JPL,
MISR Team. Satellite: Terra Sensor: MISR
Patch
reef – an isolated, often circular reef, usually within a lagoon or
embayment
- Located in shallow water
10-20' (3-6 m)
- Outer edge ringed by sand
- Dominated by large star and
brain coral colonies
Ribbon
reef – long, narrow, somewhat winding reef, usually associated with an
atoll lagoon
Table
reef – isolated reef, approaching an atoll type, but without a lagoon
Bank
Reef – Bank reefs are larger than patch reefs and are linear or
semi-circular in outline
Bank
Reef Scene
credit:
U.S. Geological Survey
- Located seaward from patch
reefs
- High species diversity
- Characterized by spur and
groove formation
Atolls
in The Maldives Landsat 7
Atolls are annular reefs that develop at or near the surface of the sea when
islands that are surrounded by reefs subside.
Atolls separate a central lagoon
and are circular or sub-circular. There are two types of atolls: deep sea atolls
that rise from deep sea and those found on the continental shelf.
View
of Midway Atoll from Space Shuttle
credit:
NOAA, NASA, Reef Check, UNEP, Reef Relief, Australian Government
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