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Deep Sea Life: Mysteries And Mountains of the Deep
The promise of the deep Flytrap Anemone, Davidson Seamount, Pacific Ocean
Image courtesy of NOAA and MBARI
Intact Lophelia pertusa reef or mound
with a redfish (Sebastes sp.)
peering out.
Image courtesy of
Fisheries and Ocean Canada/
Peches et Oceans Canada.
Crab on sponge at the Davidson Seamount off the coast of California
Images courtesy of NOAA and MBARI
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Scientists have speculated that as many as 10 million species may inhabit the deep sea —
biodiversity comparable to the world's richest tropical rainforests. Because deep-sea species live in
rarely disturbed environments and tend to be slow growing, late maturing and endemic, they are
exceptionally vulnerable to extinction. Deep-sea coral and sponge communities are largely untapped
sources of natural products with enormous potential as pharmaceuticals, enzymes, pesticides, cosmetics,
and other commercial products.
• Seamounts
• Cold-water Corals
• Deep Sea Fish
• The Promise of the Deep
Seamounts
A great deal of deep-seas biodiversity is concentrated around seamounts which are underwater mountains that rise 1,000 meters or higher from the seabed without breaking the ocean's surface. It is estimated that there may be as many as 30,000 to 100,000 seamounts worldwide. They are home to cold-water coral reefs and forests, sponge beds and hydrothermal vents, as well as the many millions of species dependent on these. And because many seamounts are located in remote surroundings –underwater islands, essentially — virtually every study finds species that were previously unknown and are endemic, meaning that they are unique to that area.
Seamounts are not only physically impressive, but like an oasis in the desert, provide an important source of food. Because of their physical characteristics and strong localized currents, they accumulate enormous quantities of plankton. The plankton, in turn, attracts a vast array of marine life, providing feeding as well as spawning grounds for myriad pelagic species, including some that have migrated across wide oceanic areas.
Home to large marine mammals, such as dolphins and whales and an extraordinary diversity of fish, together with exotic sponge and coral ecosystems, seamounts are among the world's greatest marine-biological treasures.
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Cold-water Corals
The deep sea is also home to remarkably rich coral systems. Once thought to inhabit only the warm and shallow waters of tropical and subtropical regions, corals have apparently been thriving in deep, dark and cold waters throughout the world for millions of years. Indeed, it is now thought that there are more coral species living in the dark ocean depths than in the tropical shallows.
Carbon dating of living cold-water coral reefs has revealed that the oldest may be 8,000 years old or more. Several of the coral species create complex reefs and ornate three-dimensional, forest-like structures that rival tropical coral systems in their size and complexity. Indeed, the oldest and tallest reef yet observed is 35 meters high.
Although scientists have only just begun to explore the ecological aspects of cold-water corals, it is clear that cold-water reefs are bustling with life, providing essential sanctuaries and nursing grounds for countless species.
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Deep Sea Fish
"These species recover from disturbances at an exceedingly slow rate, if at all. Whole populations can be quickly fished out."
Seamounts, and the cold-water corals they sustain, provide habitats for several commercial bottom-dwelling fish species, such as orange roughy, roundnose grenadier, blue ling, mirror dory and silver dory. Other species, for example, alfonsino, boar fish and blue-eye trevalla, are also attracted to these habitats. The concentrations of these fish around seamounts make them very attractive fishing grounds.
Sadly, studies show that the long life cycles and slow sexual maturation of deep-sea fish makes them particularly vulnerable to large-scale fishing activities. These species have dwelled in ecosystems that are rarely disturbed and that recover from disturbances at an exceedingly slow rate, if at all. Whole populations can be quickly fished out.
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The Promise of the Deep
- Of the estimated 500,000 to 10 million species living in the deep sea, the majority are yet to be discovered.
- Approximately 98 percent of the oceans' species live in, on or just above the floor of the sea.
- The estimated number of seamounts ranges from 30,000 to 100,000.
- Seamounts are home to a breathtaking array of species (for example, over 850 species were recently found on seamounts in the Tasman and Coral Seas).
- Because 15 percent or more of the breathtaking array of species being found on seamounts may be endemic (meaning that they are unique to that area — Coral and Tasman Sea seamounts have endemism rates of 29-34 percent), each unsampled seamount is a potential source of numerous undiscovered species.
- Two-thirds of all known coral species live in waters that are deep, dark, and cold — some live three miles deep and are able to survive in 30°F.
- Some cold-water corals are 5,000-8,500 years old or more, and some grow into beautiful structures that rise up to 35 meters high.
- Deep-sea corals, sponges and other habitat-forming organisms provide protection from currents and predators, nurseries for young fish, and feeding, breeding, and spawning areas for hundreds of thousands of species.
- Commercially important deep-water fish and crustacean populations found in the high seas include crabs, shrimp, cod, Pacific cod, orange roughy, armorhead, grenadier, Patagonian toothfish (aka Chilean sea bass), jacks, snappers, porgies, sharks, groupers, rockfish, Atka mackerel, and sablefish.
- Deep-sea species tend to be slow growing, late maturing and low in reproductive capacity. Many deep-water fish species live 30 years or more. Some, such as orange roughy, can live up to 150 years.
- Because deep-sea species live in rarely disturbed environments and tend to be slow growing, late maturing and endemic, they are exceptionally vulnerable to extinction.
- Deep-sea coral and sponge communities are largely untapped sources of natural products with enormous potential as pharmaceuticals, enzymes, pesticides, cosmetics, and other commercial products, for example:
- Gorgonian corals produce antibiotics;
- compounds found in certain deep-sea sponges are potent immunosuppressive and anti-cancer agents;
- some coral species contain the pain-killing compounds known as pseudopterosians;
- seafans contain high concentrations of prostaglandins (compounds used to treat asthma and heart disease).
- Ancient deep-sea corals provide valuable records of climate conditions that may assist our understanding of global climate change.
More information:
24 Sep 2004
Mysteries and Mountains of the Deep Sea
- Conserving Deep-Sea Biodiversity and Habitats
pdf; 4 pages; 607 KB
English | English
US standard | Spanish
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