The benthic zone is the ecological region at the lowest level of a body of water A body of water or waterbody is any significant accumulation of water, usually covering the Earth or another planet. The term body of water most often refers to large accumulations of water, such as oceans, seas, and lakes, but it may also include smaller pools of water such as ponds, puddles or wetlands. Rivers, streams, canals, and other such as an ocean An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface (~3.61 X 1014 m2) is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas or a lake A lake is a terrain feature , a body of liquid on the surface of a world that is localized to the bottom of basin (another type of landform or terrain feature; that is not global). Another definition is a body of fresh or salt water of considerable size that is surrounded by land. On Earth a body of water is considered a lake when it is inland,, including the sediment surface and some sub-surface layers. Organisms living in this zone are called benthos Benthos are the organisms which live on, in, or near the seabed, also known as the benthic zone. They live in or near marine sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depths. They generally live in close relationship with the substrate bottom; many such organisms are permanently attached to the bottom. The superficial layer of the soil lining the given body of water, the benthic boundary layer, is an integral part of the benthic zone, as it influences greatly the biological activity which takes place there. Examples of contact soil layers include sand Sand is a naturally occurring granular material composed of finely divided rock and mineral particles bottoms, rock outcrops, coral Corals are marine organisms in class Anthozoa of phylum Cnidaria typically living in compact colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans, which secrete calcium carbonate to form a hard skeleton, and bay mud Bay mud consists of thick deposits of soft, unconsolidated silty clay, which is saturated with water; these soil layers are situated at the bottom of certain estuaries, which are normally in temperate regions that have experienced cyclical glacial cycles. Example locations are Cape Cod Bay, Chongming Dongtan Reserve in Shanghai, China, Banc d'.
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Description
Microphotograph of typical benthic animalsThe benthic region begins at the shore line (intertidal The intertidal zone is the area that is exposed to the air at low tide and underwater at high tide (for example, the area between tide marks). This area can include many different types of habitats, including steep rocky cliffs, sandy beaches, or wetlands (e.g., vast mudflats). The area can be a narrow strip, as in Pacific islands that have only a or eulittoral The littoral zone refers to that part of a sea, lake or river that is close to the shore. In coastal environments the littoral zone extends from the high water mark, which is rarely inundated, to shoreline areas that are permanently submerged. It always includes this intertidal zone and is often used to mean the same as the intertidal zone zone) and extends downward along the surface of the continental shelf The continental shelf is the extended perimeter of each continent and associated coastal plain, and was part of the continent during the glacial periods, but is undersea during interglacial periods such as the current epoch by relatively shallow seas and gulfs out to sea. The continental shelf is a gently sloping benthic region that extends away from the land mass. At the continental shelf edge, usually about 200 meters deep, the gradient greatly increases and is known as the continental slope. The continental slope drops down to the deep sea floor. The deep-sea floor is called the abyssal plain Abyssal plains are flat or very gently sloping areas of the deep ocean basin floor. They are among the Earth's flattest and smoothest regions and the least explored. Abyssal plains cover approximately 54% of the Earth’s surface and reach depths between 3,000 and 6,000 m . They generally lie between the foot of a continental rise and a mid- and is usually about 4000 metres deep. The ocean floor is not all flat but has submarine ridges A mid-ocean ridge is an underwater mountain range, typically having a valley known as a rift running along its spine, formed by plate tectonics. This type of oceanic ridge is characteristic of what is known as an oceanic spreading center, which is responsible for seafloor spreading. The uplifted seafloor results from convection currents which rise and deep ocean trenches Trenches define one of the most important natural boundaries on the Earth’s solid surface; that between two lithospheric plates. There are three types of lithospheric plate boundaries: divergent , convergent (where one lithospheric plate sinks beneath another and returns to the mantle), and transform (where two lithospheric plates slide past known as the hadal zone.
For comparison, the pelagic zone Any water in the sea that is not close to the bottom or near to the shore is in the pelagic zone. The word pelagic comes from the Greek πέλαγος or pélagos, which means "open sea." The pelagic zone can be thought of in terms of an imaginary cylinder or water column that goes from the surface of the sea almost to the bottom, as is the descriptive term for the ecological region above the benthos, including the water-column up to the surface. Depending on the water-body, the benthic zone may include areas which are only a few inches below water, such as a stream or shallow pond; at the other end of the spectrum, benthos of the deep ocean includes the bottom levels of the oceanic abyssal zone The abyssal zone is the abyssopelagic layer of pelagic zone that contains the very deep benthic communities near the bottom of oceans. "Abyss" derives from the Greek word ἄβυσσος, meaning bottomless. At depths of 4,000 to 6,000 meters , this zone remains in perpetual darkness and never receives daylight. It is the deeper part of.
For information on animals that live in the deeper areas of the oceans see aphotic zone The aphotic zone is the portion of a lake or ocean where there is little or no sunlight. It is formally defined as the depths beyond which less than 1% of sunlight penetrates. Consequently, bioluminescence is essentially the only light found in this zone. Most food comes from dead organisms sinking to the bottom of the lake or ocean from overlying. Generally, these include life forms that tolerate cool temperatures Historically, two equivalent concepts of temperature have developed, the thermodynamic description and a microscopic explanation based on statistical physics. Since thermodynamics deals entirely with macroscopic measurements, the thermodynamic definition of temperature, first stated by Lord Kelvin, is stated entirely in empirical, measurable and low oxygen Oxygen (pronounced /ˈɒksɨdʒɨn/, OK-si-jin, from the Greek roots ὀξύς (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter), is the element with atomic number 8 and represented by the symbol O. It is a member of the chalcogen group on the periodic table, and is a highly levels, but this depends on the depth of the water.
Organisms
Main article: Benthos Benthos are the organisms which live on, in, or near the seabed, also known as the benthic zone. They live in or near marine sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depthsBenthos Benthos are the organisms which live on, in, or near the seabed, also known as the benthic zone. They live in or near marine sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depths are the organisms which live in the benthic zone, and are different from those elsewhere in the water column. Many are adapted to live on the substrate (bottom). In their habitats they can be considered as dominant creatures. Many organisms adapted to deep-water pressure cannot survive in the upper parts of the water column A water column is a conceptual column of water from surface to bottom sediments. This concept is used chiefly for environmental studies evaluating the stratification or mixing of the thermal or chemically stratified layers in a lake, stream or ocean. Some of the common parameters analyzed in the water column are: pH, turbidity, temperature,. The pressure difference can be very significant (approximately one atmosphere The standard atmosphere is an international reference pressure defined as 101,325 Pa and formerly used as unit of pressure. For practical purposes it has been replaced by the bar which is 100,000 Pa. The difference of about 1% is not significant for many applications, and is within the error range of common pressure gauges for each 10 meters of water depth).
Because light does not penetrate very deep ocean-water, the energy source for the benthic ecosystem is often organic matter from higher up in the water column which drifts down to the depths. This dead and decaying matter In biology, detritus is non-living particulate organic material . It typically includes the bodies or fragments of dead organisms as well as fecal material. Detritus is typically colonized by communities of microorganisms which act to decompose (or remineralize) the material. In terrestrial ecosystems, it is encountered as leaf litter and other sustains the benthic food chain Food chains and food webs are representations of the predator-prey relationships between species within an ecosystem or habitat; most organisms in the benthic zone are scavengers Scavenging, or necrophagy, is a carnivorous feeding behaviour in which a predator consumes corpses or carrion that were not killed to be eaten by the predator or others of its species. Scavengers play an important role in the ecosystem by contributing to the decomposition of dead animal remains. Decomposers complete this process, by consuming the or detritivores Detritivores, also known as detritus feeders or saprophages, are heterotrophs that obtain nutrients by consuming detritus . By doing so, they contribute to decomposition and the nutrient cycles. Some microorganisms A microorganism or microbe is an organism that is microscopic (too small to be seen by the naked human eye). The study of microorganisms is called microbiology, a subject that began with Anton van Leeuwenhoek's discovery of microorganisms in 1675, using a microscope of his own design use chemosynthesis In biochemistry, chemosynthesis is the biological conversion of one or more carbon molecules and nutrients into organic matter using the oxidation of inorganic molecules (e.g. hydrogen gas, hydrogen sulfide) or methane as a source of energy, rather than sunlight, as in photosynthesis. Chemoautotrophs, organisms that obtain carbon through to produce biomass Biomass, in ecology, is the mass of living biological organisms in a given area or ecosystem at a given time. Biomass can refer to species biomass, which is the mass of one or more species, or to community biomass, which is the mass of all species in the community. It can include microorganisms, plants or animals. The mass can be expressed as the.
Benthic organisms can be divided into two categories based on whether they make their home on the ocean floor or an inch or two into the ocean floor. Those living on the surface of the ocean floor are known as epifauna.[1] Those who live burrowed into the ocean floor are known as infauna.[2]
Habitats
In oceanic An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface (~3.61 X 1014 m2) is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas environments, benthic habitats A habitat is an ecological or environmental area that is inhabited by a particular species of animal, plant or other type of organism. It is the natural environment in which an organism lives, or the physical environment that surrounds (influences and is utilized by) a species population.[citation needed] can be further zoned by depth. From the shallowest to the deepest are: the epipelagic Any water in the sea that is not close to the bottom or near to the shore is in the pelagic zone. The word pelagic comes from the Greek πέλαγος or pélagos, which means "open sea." The pelagic zone can be thought of in terms of an imaginary cylinder or water column that goes from the surface of the sea almost to the bottom, as (less than 200 meters), the mesopelagic The mesopelagic (also known as the middle pelagic or twilight zone) is a pelagic zone extending from 200 m (650 ft.) down to around 1000 m (3280 ft.) below sea level. It is located between the photic epipelagic and the aphotic bathypelagic, where there is no light at all. Although some light penetrates this deep, it is insufficient for (200–1000 metres), the bathyal (1000–4000 meters), the abyssal The abyssal zone is the abyssopelagic layer of pelagic zone that contains the very deep benthic communities near the bottom of oceans. "Abyss" derives from the Greek word ἄβυσσος, meaning bottomless. At depths of 4,000 to 6,000 meters , this zone remains in perpetual darkness and never receives daylight. It is the deeper part of (4000–6000 meters) and the deepest, the hadal The hadal zone , also known as the hadopelagic zone and trench zone, is the delineation for the deepest trenches in the ocean. This zone is found from a depth of around 6,000 metres (20,000 ft) to the bottom of the ocean (below 6000 meters).
The lower zones are in deep, pressurized areas of the ocean. Because of the high pressures and seclusion neither tidal changes nor human impacts have had much of an effect on these areas, and the habitats have not changed much over the years. Many benthic organisms have retained their historic evolutionary characteristics. Some organisms are significantly larger than their relatives living in shallower zones, largely because of higher oxygen concentration in deep water.[3]
It is not easy to map or observe these organisms and their habitats, and most observation has been done through remote controlled submarines A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has only limited underwater capability. The term submarine most commonly refers to large crewed autonomous vessels; however, historically or more casually, submarine can also refer to medium sized or smaller vessels ,.
See also
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References
- ^ http://www.merriam-webster.com/dictionary/epifaunal
- ^ http://www.merriam-webster.com/dictionary/epifaunal
- ^ Royal Belgian Institute of Natural Sciences, news item March 2005
External links
- Vertical Life Zones and Biodiversity Seminar at Fathom.com
- Data Archive for Seabed Species and Habitats from the UK Marine Data Archive Centre
- Seafloor Warming - Cluster of Excellence "Future Ocean" , Kiel
Categories: Aquatic biomes | Aquatic ecology | Fisheries science | Oceanography
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7thSpace Interactive (press release), NY
Xenoturbella bocki is a morphologically simple benthic marine worm recently found to belong among the deuterostomes. Here we present analyses comparing the Xenoturbella bocki mitochondrial gene order, genetic code and control region to those of other ...
Andrea
Fri, 02 Oct 2009 15:43:08 GM
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