Deep-sea community
This article needs additional citations for verification. (January 2021) |
A deep-sea community is any community of organisms associated by a shared habitat in the deep sea. Deep sea communities remain largely unexplored, due to the technological and logistical challenges and expense involved in visiting this remote biome. Because of the unique challenges (particularly the high barometric pressure, extremes of temperature and absence of light), it was long believed that little life existed in this hostile environment. Since the 19th century however, research has demonstrated that significant biodiversity exists in the deep sea.
The three main sources of energy and nutrients for deep sea communities are marine snow, whale falls, and chemosynthesis at hydrothermal vents and cold seeps.
History
Prior to the 19th century scientists assumed life was sparse in the deep ocean. In the 1870s Sir Charles Wyville Thomson and colleagues aboard the Challenger expedition discovered many deep-sea creatures of widely varying types.
The first discovery of any deep-sea
The Challenger Deep is the deepest surveyed point of all of Earth's oceans; it is located at the southern end of the Mariana Trench near the Mariana Islands group. The depression is named after HMS Challenger, whose researchers made the first recordings of its depth on 23 March 1875 at station 225. The reported depth was 4,475 fathoms (8184 meters) based on two separate soundings. In 1960, Don Walsh and Jacques Piccard descended to the bottom of the Challenger Deep in the Trieste bathyscaphe. At this great depth a small flounder-like fish was seen moving away from the spotlight of the bathyscaphe.
The Japanese
Environment
Darkness
The ocean can be conceptualized as being divided into various zones, depending on depth, and presence or absence of sunlight. Nearly all life forms in the ocean depend on the photosynthetic activities of phytoplankton and other marine plants to convert carbon dioxide into organic carbon, which is the basic building block of organic matter. Photosynthesis in turn requires energy from sunlight to drive the chemical reactions that produce organic carbon.[5]
The stratum of the
The euphotic zone is somewhat arbitrarily defined as extending from the surface to the depth where the light intensity is approximately 0.1–1% of surface sunlight
Since the average depth of the ocean is about 3688 meters,[10] the photic zone represents only a tiny fraction of the ocean's total volume. However, due to its capacity for photosynthesis, the photic zone has the greatest biodiversity and biomass of all oceanic zones. Nearly all primary production in the ocean occurs here. Any life forms present in the aphotic zone must either be capable of movement upwards through the water column into the photic zone for feeding, or must rely on material sinking from above,[5] or must find another source of energy and nutrition, such as occurs in chemosynthetic archaea found near hydrothermal vents and cold seeps.
Hyperbaricity
These animals have
Temperature
The two areas of greatest and most rapid
Hydrothermal vents are the direct contrast with constant temperature. In these systems, the temperature of the water as it emerges from the "black smoker" chimneys may be as high as 400 °C (it is kept from boiling by the high hydrostatic pressure) while within a few meters it may be back down to 2–4 °C.[12]
Salinity
Salinity is constant throughout the depths of the deep sea. There are two notable exceptions to this rule:
- In the Mediterranean Intermediate Water can persist for thousands of kilometers away from its source.[16]
- Brine pools are large areas of brine on the seabed. These pools are bodies of water that have a salinity that is three to five times greater than that of the surrounding ocean. For deep sea brine pools the source of the salt is the dissolution of large salt deposits through salt tectonics. The brine often contains high concentrations of methane, providing energy to chemosynthetic extremophiles that live in this specialized biome. Brine pools are also known to exist on the Antarctic continental shelf where the source of brine is salt excluded during formation of sea ice. Deep sea and Antarctic brine pools can be toxic to marine animals. Brine pools are sometimes called seafloor lakes because the dense brine creates a halocline which does not easily mix with overlying seawater. The high salinity raises the density of the brine, which creates a distinct surface and shoreline for the pool.[17]
The
Zones
Mesopelagic
The mesopelagic zone is the upper section of the midwater zone, and extends from 200 to 1,000 metres (660 to 3,280 ft) below sea level. This is colloquially known as the "twilight zone" as light can still penetrate this layer, but it is too low to support photosynthesis. The limited amount of light, however, can still allow organisms to see, and creatures with a sensitive vision can detect prey, communicate, and orientate themselves using their sight. Organisms in this layer have large eyes to maximize the amount of light in the environment.[18]
Most mesopelagic fish make daily
Mesopelagic fish usually lack defensive spines, and use colour and bioluminescence to camouflage them from other fish. Ambush predators are dark, black or red. Since the longer, red, wavelengths of light do not reach the deep sea, red effectively functions the same as black. Migratory forms use countershaded silvery colours. On their bellies, they often display photophores producing low grade light. For a predator from below, looking upwards, this bioluminescence camouflages the silhouette of the fish. However, some of these predators have yellow lenses that filter the (red deficient) ambient light, leaving the bioluminescence visible.[22]
Bathyal
The bathyl zone is the lower section of the midwater zone, and encompasses the depths of 1,000 to 4,000 metres (3,300 to 13,100 ft).
Abyssal and hadal
The abyssal zone remains in perpetual darkness at a depth of 4,000 to 6,000 metres (13,000 to 20,000 ft).
Energy sources
Marine snow
The upper photic zone of the ocean is filled with particle organic matter (POM) and is quite productive, especially in the coastal areas and the upwelling areas. However, most POM is small and light. It may take hundreds, or even thousands of years for these particles to settle through the water column into the deep ocean. This time delay is long enough for the particles to be remineralized and taken up by organisms in the food webs.
Scientists at Woods Hole Oceanographic Institution conducted an experiment three decades ago in deep Sargasso Sea looking at the rate of sinking.[30] They found what became known as marine snow in which the POM are repackaged into much larger particles which sink at much greater speed, 'falling like snow'.
Because of the sparsity of food, the organisms living on and in the bottom are generally opportunistic. They have special adaptations for this extreme environment: rapid growth, effect larval dispersal mechanism and the ability to use a 'transient' food resource. One typical example is wood-boring
Whale falls
For the deep-sea ecosystem, the death of a whale is the most important event. A dead whale can bring hundreds of tons of organic matter to the bottom. Whale fall community progresses through three stages:[31]
- Mobile scavenger stage: Big and mobile deep-sea animals arrive at the site almost immediately after whales fall on the bottom. sleeper sharks and hagfishare all scavengers.
- Opportunistic stage: Organisms arrive which colonize the bones and surrounding sediments that have been contaminated with organic matter from the carcass and any other tissue left by the scavengers. One genus is Osedax,[32] a tube worm. The larva is born without sex. The surrounding environment determines the sex of the larva. When a larva settles on a whale bone, it turns into a female; when a larva settles on or in a female, it turns into a dwarf male. One female Osedax can carry more than 200 of these male individuals in its oviduct.
- gastropodsand other sulphur-loving creatures move in.
Chemosynthesis
Hydrothermal vents
New ocean basin material is being made in regions such as the Mid-Atlantic ridge as tectonic plates pull away from each other. The rate of spreading of plates is 1–5 cm/yr. Cold sea water circulates down through cracks between two plates and heats up as it passes through hot rock. Minerals and sulfides are dissolved into the water during the interaction with rock. Eventually, the hot solutions emanate from an active sub-seafloor rift, creating a hydrothermal vent.
Chemosynthesis of bacteria provide the energy and organic matter for the whole food web in vent ecosystems. These vents spew forth very large amounts of chemicals, which these bacteria can transform into energy. These bacteria can also grow free of a host and create mats of bacteria on the sea floor around hydrothermal vents, where they serve as food for other creatures. Bacteria are a key energy source in the food chain. This source of energy creates large populations in areas around hydrothermal vents, which provides scientists with an easy stop for research. Organisms can also use chemosynthesis to attract prey or to attract a mate.[33]
Hydrothermal vents are entire ecosystems independent from sunlight, and may be the first evidence that the earth can support life without the sun.
Cold seeps
A
Ecology
Deep sea food webs are complex, and aspects of the system are poorly understood. Typically, predator-prey interactions within the deep are compiled by direct observation (likely from remotely operated underwater vehicles), analysis of stomach contents, and biochemical analysis. Stomach content analysis is the most common method used, but it is not reliable for some species.[35]
In deep sea pelagic ecosystems off of California, the trophic web is dominated by
Deep sea research
Humans have explored less than 4% of the ocean floor, and dozens of new species of deep sea creatures are discovered with every dive. The submarine DSV Alvin—owned by the US Navy and operated by the Woods Hole Oceanographic Institution (WHOI) in Woods Hole, Massachusetts—exemplifies the type of craft used to explore deep water. This 16 ton submarine can withstand extreme pressure and is easily manoeuvrable despite its weight and size.
The extreme difference in pressure between the sea floor and the surface makes creatures' survival on the surface near impossible; this makes in-depth research difficult because most useful information can only be found while the creatures are alive. Recent developments have allowed scientists to look at these creatures more closely, and for a longer time. Marine biologist Jeffery Drazen has explored a solution: a pressurized fish trap. This captures a deep-water creature, and adjusts its internal pressure slowly to surface level as the creature is brought to the surface, in the hope that the creature can adjust.[37]
Another scientific team, from the Université Pierre-et-Marie-Curie, has developed a capture device known as the PERISCOP, which maintains water pressure as it surfaces, thus keeping the samples in a pressurized environment during the ascent. This permits close study on the surface without any pressure disturbances affecting the sample.[38]
See also
- Deep sea fish
- Movile Cave
References
- ^ a b Minerals Management Service Gulf of Mexico OCS Region (November 2006). "Gulf of Mexico OCS Oil and Gas Lease Sales: 2007–2012. Western Planning Area Sales 204, 207, 210, 215, and 218. Central Planning Area Sales 205, 206, 208, 213, 216, and 222. Draft Environmental Impact Statement. Volume I: Chapters 1–8 and Appendices". U.S. Department of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans. page 3-27. PDF Archived 2009-03-26 at the Wayback Machine
- ^ "Robot sub reaches deepest ocean". BBC News. 3 June 2009. Retrieved 2009-06-03.
- ^ a b University of Hawaii Marine Center (4 June 2009). "Daily Reports for R/V KILO MOANA June & July 2009". Honolulu, Hawaii: University of Hawaii. Archived from the original on 19 September 2009. Retrieved 24 June 2010.
- ^ University of Hawaii Marine Center (4 June 2009). "Inventory of Scientific Equipment aboard the R/V KILO MOANA". Honolulu, Hawaii: University of Hawaii. Archived from the original on 13 June 2010. Retrieved 18 June 2010.
- ^ PMID 19901326.
- ^ S2CID 29314639. Archived from the original (PDF) on 10 June 2011. Retrieved 18 June 2010.)
{{cite book}}
:|journal=
ignored (help - ^ a b "Photic zone". Encyclopædia Britannica. 2010. Retrieved 18 June 2010.
- ^ a b c d Jeananda Col (2004). "Twilight Ocean (Disphotic) Zone". EnchantedLearning.com. Retrieved 18 June 2010.
- ^ S2CID 8423647.
- ^ National Oceanic and Atmospheric Administration (2 December 2008). "How deep is the ocean?". Washington, DC: National Oceanic and Atmospheric Administration. Retrieved 19 June 2010.
- ^ "The Deep Sea at MarineBio.org – Ocean biology, Marine life, Sea creatures, Marine conservation". Archived from the original on 2009-01-06. Retrieved 2011-05-08.
- ^ Nybakken, James W. Marine Biology: An Ecological Approach. Fifth Edition. Benjamin Cummings, 2001. p. 136–141.
- ISBN 978-0-314-06339-7.
- ^ Pinet 1996, p. 206.
- ^ Pinet 1996, pp. 206–207.
- ^ Pinet 1996, p. 207.
- ^ NOAA exploration of a brine pool
- ISBN 978-0-7614-7176-9.
- ISBN 978-0-203-88522-2.
- ^ ISBN 978-0-13-100847-2.
- PMID 1251208.
- S2CID 86353657.
- ^ a b "Bathypelagic zone". Layers of the ocean. National Weather Service. Archived from the original on 7 February 2017. Retrieved 1 January 2021.
{{cite web}}
: CS1 maint: bot: original URL status unknown (link) - ^ ISBN 978-84-491-0299-8.
- ^ Ryan, Paddy (21 September 2007). "Deep-sea creatures: The bathypelagic zone". Te Ara – the Encyclopedia of New Zealand. Retrieved 4 September 2016.
- PMID 24591588.
- ^ "NOAA Ocean Explorer: History: Quotations: Soundings, Sea-Bottom, and Geophysics". NOAA, Office of Ocean Exploration and Research. Retrieved 4 September 2016.
- PMID 18584909. Archived from the original(PDF) on 2011-07-20. Retrieved 2016-09-04.
- ISBN 978-0-12-026132-1.
- ^ "Marine Snow and Fecal Pellets".
- ^ Shana Goffredi, Unusual benthic fauna associated with a whale fall in Monterey Canyon, California, Deep-Sea Research, 1295–1304, 2004
- ^ Noah K. Whiteman, Between a whale bone and the deep blue sea: the provenance of dwarf males in whale bone-eating tube worms, Molecular Ecology, 4395–4397, 2008
- ^ Chemosynthesis
- ^ Botos, Sonia. "Life on a hydrothermal vent".
- ^ PMID 29212727.
- from the original on December 20, 2017. Retrieved 2017-12-20.
- ^ New Trap May Take Deep-Sea Fish Safely Out of the Dark
- ^ Lever AM (31 July 2008). "Live fish caught at record depth". BBC News. Retrieved 18 February 2011.
Further reading
- Kupriyanova, E.K.; Vinn, O.; Taylor, P.D.; Schopf, J.W.; Kudryavtsev, A.B.; Bailey-Brock, J. (2014). "Serpulids living deep: calcareous tubeworms beyond the abyss". Deep-Sea Research Part I. 90: 91–104. .