Dictionary Definition
benthic adj : of or relating to or happening on
the bottom under a body of water [syn: benthal, benthonic]
User Contributed Dictionary
Pronunciation
- /'bɛnθɪk/
Adjective
Translations
of the benthos on the seafloor
- Dutch: benthonisch
- German: benthonisch
Antonyms
See also
Extensive Definition
The benthic zone is the ecological region at the
lowest level of a body of
water such as an ocean
or a lake, including the
sediment surface and some sub-surface layers. Organisms living in
this zone are called benthos. They generally live in
close relationship with the substrate bottom; many such organisms
are permanently attached to the bottom. Generally, these include
life forms that tolerate cool temperatures and low
oxygen levels, but this
depends on the depth of the water. For information on animals that
live in the deepest areas of the oceans see aphotic
zone. The superficial layer of the soil lining the given body
of water 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 bottoms, rock outcrops,
coral, and bay mud.
For comparison, the pelagic zone
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.
Organisms
Benthos 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. The pressure difference can be very significant (approximately one atmosphere 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 sustains the benthic food chain;
most organisms in the benthic zone are scavengers or detritivores.
Habitats
In oceanic environments, benthic habitats can be further subdivided based on depth. From the shallowest to the deepest are: the estuarine zone — less than 200 meters; then the bathyal zone — 200-2000 meters; the abyssal — 2000-6000 meters; and the deepest, the hadal zone — over 6000 meters.All these zones are in deep, pressured areas of
the ocean. Because of the high pressure and seclusion neither tidal
changes nor human interference has 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 have significantly changed
size.
Humans are not able to map or observe these
organisms and their habitats easily, and most observation has been
done through remote controlled submarines.
See also
References
- Fathom
- Data Archive for Seabed Species and Habitats from the UK Marine Data Archive Centre
benthic in Belarusian: Бенталь
benthic in German: Benthal
benthic in Estonian: Bentaal
benthic in Dutch: Benthische zone
benthic in Polish: Bental