Deepwater Corals

Deepwater Corals: What Are They?

deepwater-coralsDeep water and shallow water coral reef communities are richly diverse and provide habitat for many species. Shallow water coral reef systems have been well studied partly due to their proximity to shore. Deep water corals and associated habitats can only be studied with technology such as manned submersibles, remotely operated vehicles (ROV) and autonomous underwater vehicles (AUV). Only a small percentage of deep water reefs have been described.

Unlike reef-building tropical corals, deep water corals exist beyond the reach of sunlight. As opposed to shallow water corals, deep water coral polyps do not contain the symbiotic algae that provide their tropical cousins with their color and some of their nutrition. Instead, deep water corals rely on catching passing food in the water column. As a result, deep water corals grow very slowly and are typically white. Colonies tend to be found in areas of strong currents, which supply food and remove sediments that would otherwise smother the coral polyps. They are also typically found along rocky ledges or in narrow regions. Deep water coral systems are receiving increased attention worldwide.

Oculina varicosa

deepwater-corals1Oculina varicosa, or ivory tree coral, is a slow–growing, branchlike coral whose thickets provide spawning sites for numerous species of reef–dwelling fish, including groupers and snappers. Oculina colonies grow in water depths of several meters to greater than 100 meters. Unlike those found in shallow water--which are relatively small with stout, club–like branches—deep water colonies can be delicate clusters of several meters in diameter. Based on average growth rates, some reefs are thought to be 1,500 years old! Oculina reefs typically occur in regions on the shelf edge where water flows upward from depth. Studies have shown a very high diversity of invertebrates, with hundreds of species living in the nooks and crannies of a single coral head, while species of grouper have been known to form large spawning aggregations in Oculina habitat.

Oculina reefs grow along the U. S. continental shelf with concentrations occurring off the east–central coast of Florida. Limestone "pinnacles," lie near the 80–meter depth contour off east–central Florida and extend tens of meters above the surrounding sea floor. This area, called the Oculina Bank, is located approximately 15 miles offshore Fort Pierce. The Oculina Bank has suffered extensive habitat damage due to mobile fishing gear (trawls and dredges) and anchoring activities. (Photo credit: NURC/UNCW).

Lophelia pertusa

Lophelia pertusa is another widespread branching, tree-like, snow-white, deepwater coral.  Although widespread throughout the world, Lophelia reefs form only under a particular set of favorable conditions, including bottom temperatures below 50 degrees F.  Mature Lophelia can grow to several meters in diameter and 1-3 meters high.  Live Lophelia coral off the coast of Florida is estimated to be 700 years old.  Lophelia is fragile and easily broken by strong bottom currents or upon contact with large creatures.  Hence, Lophelia reefs are carpeted with a dense layer of living and dead coral rubble, a distinctive habitat in its own right.  Lophelia reefs are true biological oases in the deep sea.  The South Atlantic region is home to thriving Lophelia ecosystems that may be among the most extensive in the world.

Learn more at NOAA's Coral Reef Information System and Coral Reef Conservation Program. Or visit the global coral information system ReefBase to explore coral resources, threats, and photos from around the world.

VIDEO - "Revealing The Deep: Exploring the World of Deepwater Coral Ecosystems"

This film produced by Art Howard Productions in 2007 uses stunning underwater video and photography to introduce the viewer to deepwater coral ecology, research, and Council management efforts to conserve these unique ecosystems.

Segment 1: Revealing The Deep

Segment 2: Revealing The Deep

Segment 3: Revealing The Deep

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