Deepwater

Deepwater Coral

Not all coral species live in tropical, shallow waters. There are many species of coral which exist and thrive far below the ocean's surface. Deep-water corals (DWC), like tropical corals, can be very large, three dimensional skeletal frameworks that host a variety of organisms. However, unlike tropical reefs, cold corals do not depend on light to survive and instead rely on extended polyps for food. Less is known about cold corals than tropical corals, and new cold-water corals are being discovered as more of the ocean is explored.

more info found at

need to introduce more terminology and acronyms here: synonyms:

• Deep-water coral (DWC) = Deep-sea coral = Cold Water Coral (CWC)---this one is important. Lots of academic journals refer to DWC as CWC. Reason being: most deep-sea reefs are made up of cold water coral

Other terms: --“Mesophotic reefs”= DWC reefs, reefs without light, 30–150 m below sea level ---Mesophotic Coral Ecosystems--“MECs”

Habitat

Deepwater corals grow in all the world’s ocean basins, including the waters of the United Kingdom, Australia, New Zealand, Canada, Ecuador, Japan, Norway, and the United States.They can be found in waters as deep as 6,000m and as cold as -1ºC. However, temperature is an influencing factor of coral distribution, and they are most commonly found in waters ranging from 4 to 12 C. Other factors influencing coral distribution include salinity and competitive interactions with other organisms like sponges and algae.

Cold corals, as they are also called, often are found on seamounts, ocean canyons, and continental shelves and slopes. Corals require a hard surface on which to attach, which could be exposed rock, substrate, or even dead coral. They generally colonize areas where strong currents are found, as corals rely on the steady flow of water to supply them with food, disperse larvae, and to remove wastes and sediments. For this reason, corals are often found specifically on seamounts due to the strong currents.

Diet

Due to the lack of sunlight in their environment, deep-water corals do not depend on symbiotic relationships with zooalanthalae as their shallow water counterparts do. Deep-water corals are completely heterotrophic out of necessity. Rather than relying primarily on photosynthesizing zooanthalae for energy, DWC must filer feed through the use of extended polyps which capture food particles and microorganisms as they float by. Consequently, DWC rely heavily on ocean currents to bring them their food source and can be greatly impacted by shifts in currents.

However, recent research has indicated that there may be a link between chemosynthesizing bacteria and mircoorganisms of the deep sea and DWC. A 2008 study by Jensen S. et al. has uncovered the possibility of symbiotic relationships between deep-water coral and methanotropes, which are microorganisms that obtain energy from underwater methane seeps.

Life Cycle

Due to the difficulties inherent in observation of deep-water coral, little is known about their life cycle. Structural similarities between deep and shallow water corals have led scientists to believe that DWC likely undergo a life cycle similar to tropical corals.

-i.e. drifting medusa, attached coral polyp, mature coral structure, rubble---> mention the after-life phase? coral rubble- include link to "Threats to Coral", natural threats- bioerosion- boring of sponges.

-post link to Rachel's reproduction page for life cycle--- how do we link two Wiki pages together?

Species

Leiopathes glaberrima

Black corals are the oldest known marine organisms. They live in excess of 4,000 years. Black corals have dark skeletons and irregularly branching, tree-like structures. The coral polyps attach to the base of the skeleton, and their mouths are located at the other end, ringed in tentacles to catch food. . Unlike tropical coral reefs, cold corals do not contain zooxanthellae within their tissues, so they must catch their food on passing currents. They are found in both the Pacific and Atlantic, though their complete distribution is unclear. . Deep-water Black Coral is threatened by habitat degradation and also trade in live corals for aquariums. . While the trade is small, it is not sustainable as slow growing as black coral.

Lophelia pertusa

Lophelia pertusa are stony, deep-water corals mainly occurring mainly on the continental shelf and are one of the few species able to build a coral framework in the deep ocean. They are rarely attached to soil substrata, but occur on soft ocean bottoms greater than 150m and even occasionally on oil industry structures where currents are strong. The skeletons of Lophelia pertusa polyps occur in bush-like colonies that may join together to form a larger reef, joined together by their external calcareous skeletons. . Individual polyps are white, pink, or yellowish, and contain up to 50 tentacles. Within the reef, stony corals are protected against other animals growing in the reef by a layer of mucus. Even so, stony corals are a biodiversity hotspot and provide habitat to a variety of species at the edge of the continental shelf. They are threatened by bottom trawling and oil extraction. . It is also though that deep, cold-water, stony corals are among the first marine organisms to be affect by ocean acidification. .

Importance

Just as with tropical coral reefs, deep water corals are important for a number of reasons, mainly due to their integral role in the functioning of other systems.

• Deepwater coral reefs provide critical habitat to a disproportionate number of marine species. There is high species diversity around cold corals as well as high endemism. Cold corals are essential as nurseries to juvenile fish and the framework of corals create sub-habitats for a variety of marine organisms.
• Cold corals are commercially important in that they provide deep-sea habitats to many commercial fish species. Off the Aleutian Islands, 85% of commercial fisheries are associated with cold corals.
• Corals are also an important resource for new medicines.The chemicals that corals produce have potential to be used in fields such as oncology to create novel medicines such as anti-tumor compounds.
• Another source of coral importance is the use of coral in paleoclimatology. Since deep water corals are so long lived, they provide important clues about past ocean temperatures and chemistry.
• Coral are also used in jewelry, and can support local and commercial industries, though this aspect of coral use is not always sustainable, and can also be a direct, physical threat to the coral.

Threats¦

Natural

As in any ecosystem, deep-water coral experiences negative effects from other members of the benthic plant and animal communities. The major natural factor which negaticely impact DWC growth is bioerosion.

Anthropogenic

Many of the most devastating threats facing deep-water coral reefs are posed by humans. These threats stem from particular practices such as unsustainable fishing methods and also from lifestyle choices which affect the planet as a whole.

Bottom Trawling

One of the greatest threats to deep-water coral is the affect of bottom trawling. Bottom trawling has been shown to smooth out the sea floor and destroy habitat for corals. Bottom trawling directly affects reefs by catching coral in fishing nets and removing the coral framework. It also destroys the coral itself by shattering the fragile and easily broken skeletons. If enough coral is removed or damaged, the reef can reach a size where it is not longer sexually viable and does not have enough members to reproduce. Recruitment of larvae becomes sporadic. . This is particularly significant because cold corals are slow growing and take thousands of years to fully develop. .

Bottom trawling has increased in recent years due to the overfishing of shallow waters. However, bottom trawling can be counterproductive in that by destroying deep-water reefs, fishermen also destroy critical habitat for many commercial fish species. The new technology used in these deep-water fisheries has shown an increased, negative affect on coral species, characterized by heavy coral by-catch. However, as coral reefs have been removed, the incidence of by catch has decreased.

Climate Change

While global temperature fluctuation might not be as big a problem to these stoic survivors of the deep, side effects of temperature changes are an issue.

-brief discussion of how climate change affects ocean currents

Since they are a stationary species, many deep-water corals depend heavily on ocean currents to bring them food particles on which to filter feed. Furthermore, they are impacted by shifts in ocean currents even more so than shallow reef species because they do not have the option of living on energy from photosynthesis of zooanthalae. What the currents bring these corals is all that they will have access to.

Also, climate change has further-reaching impacts on ocean water itself.

Ocean Acidification

-briefly explain ocean acidification---link to more in-depth wiki page? -rising levels of CO2, higher levels of carbon in ocean, can cause stunted growth and more fragile skeletons

--While shallow water corals share the same water and are also damaged by ocean acidification, This problem is significantly worse for deep-water corals because they grow more slowly, so any inhibition at all to normal growth patterns could be extremely harmful or detrimental. ---Harder for DWC to recover.

Other threats include

• Oil and gas exploration, especially in the event of oil spills
• Jewelry or curios made from cold corals

Conservation

-MPAs

-Areas of restricted fishing equipment-- i.e. no trawling zones

-Legislation- include case study of successful conservation of Darwinian Mounds

Challenges with Conservation

-Challenges to Conservation efforts- So little is known about DWC that it is difficult to gauge the current situation. A vast majority of the ocean's floor remains unexplored, and with that new territory is the possibility of undiscovered deep-water coral forests.

-Challenges to legislation- It is difficult to advocate for these corals and recommend specific courses of action when so little is known about them and their location, in particular.

Further Links

Deepwater corals are comparable to trees