Marine biology dredge

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A shallow-water dredge from the 1870s Challenger expedition Britannica Dredge and Dredging 15.jpg
A shallow-water dredge from the 1870s Challenger expedition

The marine biology dredge is used to sample organisms living on a rocky bottom or burrowing within the smooth muddy floor of the ocean (benthic) species).The dredge is pulled by a boat and operates at any depth on a cable or line, generally with a hydraulic winch. The dredge digs into the ocean floor and bring the animals to the surface where they are caught in a net that either follows behind or is a part of the digging apparatus.

Organism Any individual living physical entity

In biology, an organism is any individual entity that embodies the properties of life. It is a synonym for "life form".

Ocean A body of water that composes much of a planets hydrosphere

An ocean is a body of water that composes much of a planet's hydrosphere. On Earth, an ocean is one of the major conventional divisions of the World Ocean. These are, in descending order by area, the Pacific, Atlantic, Indian, Southern (Antarctic), and Arctic Oceans. The word "ocean" is often used interchangeably with "sea" in American English. Strictly speaking, a sea is a body of water partly or fully enclosed by land, though "the sea" refers also to the oceans.


Early dredging samplers did not have a closing device, and many organisms were washed out. This led to a mistaken impression that the deep-sea bed lacked species diversity, as theorised by Forbes in his Azoic hypothesis. Later samplers devised by Howard L. Sanders and the Epibenthic sled designed by Robert Hessler showed that deep-sea bottoms are sometimes rich in soft-bottom benthic species.

The Azoic hypothesis is a superseded scientific theory proposed by Edward Forbes in 1843, stating that the abundance and variety of marine life decreased with increasing depth and, by extrapolation of his own measurements, Forbes calculated that marine life would cease to exist below 300 fathoms.

Epibenthic sled An instrument designed to collect benthic and benthopelagic faunas from the deep sea

An Epibenthic sled is an instrument designed to collect benthic and benthopelagic faunas from the deep sea. The sled is made from a steel frame consisting of two skids and stabilizing planes to keep it from sinking too deep into the mud. Attached to the frame is a 1 mm mesh net to collect the samples. The sled is towed along the seafloor at the sediment water interface. The device has a mechanically operated door that is closed when the sled is mid water and opens when it reaches the seafloor. When the fauna is collected, the door closes again to preserve the sample on the long trek back through the water column. The door prevents washing of the sample and loss of organisms through turbulence generated as the net is lifted out. The epibenthic sled can also be used with external sensors and cameras.


"Naturalists using the dredge", a plate from William Henry Harvey's The Seaside Book HarveySeasideBook.jpg
"Naturalists using the dredge", a plate from William Henry Harvey's The Seaside Book

The first marine biology dredge was designed by Otto Friedrich Müller and in 1830 the results of two dredging expeditions undertaken by Henri Milne-Edwards and his friend Jean Victoire Audouin during 1826 and 1828 in the neighbourhood of Granville were published. This was remarkable for clearly distinguishing the marine fauna of that portion of the French coast into four zones.

Otto Friedrich Müller Danish zoologist

Otto Friedrich Müller, also Mueller was a Danish naturalist.

Henri Milne-Edwards French zoologist

Henri Milne-Edwards was an eminent French zoologist.

Müller's design was modified by the Dublin naturalist Robert Ball in 1838 and at the Birmingham meeting of the British Association for the Advancement of Science in 1839 a committee was appointed for dredging research with a view to the investigation of the marine zoology of Great Britain, the illustration of the geographical distribution of marine animals, and the more accurate determination of the fossils of the Pliocene period. The committee was led by Edward Forbes. Later annual reports of the British Association contained communications from the English, Scottish and Irish branches of the committee, and in 1850 Forbes submitted its first general report on British marine zoology. Ball's dredge was still in use in 1910.

Robert Ball (naturalist) naturalist

Robert Ball was an Irish naturalist. He served as the Director of the Dublin University Museum, and developed a method of dredging known as "Ball's dredge."

The Pliocene Epoch is the epoch in the geologic timescale that extends from 5.333 million to 2.58 million years BP. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch. Prior to the 2009 revision of the geologic time scale, which placed the four most recent major glaciations entirely within the Pleistocene, the Pliocene also included the Gelasian stage, which lasted from 2.588 to 1.806 million years ago, and is now included in the Pleistocene.

Edward Forbes Manx naturalist

Professor Edward Forbes FRS, FGS was a Manx naturalist.

In the 20th century the 'anchor-dredge' was developed to sample deep burrowing animals. It is not towed but digs in, and is released, in the manner of an anchor.

The wide variety of dredges and other benthic sampling equipment makes site comparison difficult.

USS <i>Albatross</i> (1882)

The second USS Albatross, often seen as USFC Albatross in scientific literature citations, was an iron-hulled, twin-screw steamer in the United States Navy and reputedly the first research vessel ever built especially for marine research.

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Benthos community of organisms which live on, in, or near the seabed

Benthos is the community of organisms that live on, in, or near the seabed, river, lake, or stream bottom, also known as the benthic zone. This community lives in or near marine or freshwater sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depths.

The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth. The word "pelagic" is derived from Ancient Greek πέλαγος (pélagos), meaning '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. Conditions in the water column change with distance from the surface (depth), e.g. the pressure increases; the temperature, and the amount of light decreases; the salinity, the amount of dissolved oxygen, and micronutrients (e.g. Fe++, Mg++, Ca++) all change. Depending on the depth, the water column, rather like the Earth's atmosphere, may be divided into different layers.

Fauna set of animal species in any particular region and time

Fauna is all of the animal life present in a particular region or time. The corresponding term for plants is flora. Flora, fauna and other forms of life such as fungi are collectively referred to as biota. Zoologists and paleontologists use fauna to refer to a typical collection of animals found in a specific time or place, e.g. the "Sonoran Desert fauna" or the "Burgess Shale fauna". Paleontologists sometimes refer to a sequence of faunal stages, which is a series of rocks all containing similar fossils. The study of animals of a particular region is called faunistics.

Benthic zone the region at the lowest level of a body of water including the sediment surface and some sub-surface layers

The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. Organisms living in this zone are called benthos and include microorganisms as well as larger invertebrates, such as crustaceans and polychaetes. Organisms here generally live in close relationship with the substrate and many are permanently attached to the bottom. The benthic boundary layer, which includes the bottom layer of water and the uppermost layer of sediment directly influenced by the overlying water, is an integral part of the benthic zone, as it greatly influences the biological activity that takes place there. Examples of contact soil layers include sand bottoms, rocky outcrops, coral, and bay mud.

Seabed The bottom of the ocean

The seabed is the bottom of the ocean.

Meroplankton organisms that are planktonic for only a part of their life cycles

Meroplankton is a wide variety of planktonic organisms, which spend a portion of their lives in the benthic region of the ocean. These organisms do not remain as plankton permanently, rather, they are planktonic components in transition, which eventually become larger organisms. Meroplankton can be contrasted with holoplankton, which are planktonic organisms that stay in the pelagic zone as plankton throughout their entire life cycle.

Demersal zone The part of the water column near to the seabed and the benthos

The demersal zone is the part of the sea or ocean consisting of the part of the water column near to the seabed and the benthos. The demersal zone is just above the benthic zone and forms a layer of the larger profundal zone.

Sediment Profile Imagery (SPI) is an underwater technique for photographing the interface between the seabed and the overlying water. The technique is used to measure or estimate biological, chemical, and physical processes occurring in the first few centimetres of sediment, pore water, and the important benthic boundary layer of water. Time-lapse imaging (tSPI) is used to examine biological activity over natural cycles, like tides and daylight or anthropogenic variables like feeding loads in aquaculture. SPI systems cost between tens and hundreds of thousands of dollars and weigh between 20 and 400 kilograms. Traditional SPI units can be effectively used to explore continental shelf and abyssal depths. Recently developed SPI-Scan or rSPI systems can now also be used to inexpensively investigate shallow (<50m) freshwater, estuarine, and marine systems.

Fishing dredge

A fishing dredge, also known as a scallop dredge or oyster dredge, is a kind of dredge which is towed along the bottom of the sea by a fishing boat in order to collect a targeted edible bottom-dwelling species. The gear is used to fish for scallops, oysters and other species of clams, crabs, and sea cucumber. The dredge is then winched up into the boat and emptied. Dredges are also used in connection with the work of the naturalist in marine biology, notably on the Challenger Expedition.

Bottom feeder

A bottom feeder is an aquatic animal that feeds on or near the bottom of a body of water. Biologists often use the terms benthos — particularly for invertebrates such as shellfish, crabs, crayfish, sea anemones, starfish, snails, bristleworms and sea cucumbers — and benthivore or benthivorous, for fish and invertebrates that feed on material from the bottom. However the term benthos includes all aquatic life that lives on or near the bottom, which means it also includes non-animals, such as plants and algae. Biologists also use specific terms that refer to bottom feeding fish, such as demersal fish, groundfish, benthic fish and benthopelagic fish. Examples of bottom feeding fish species groups are flatfish, eels, cod, haddock, bass, grouper, carp, bream (snapper) and some species of catfish and shark.

Cambrian substrate revolution

The "Cambrian substrate revolution" or "Agronomic revolution", evidenced in trace fossils, is the diversification of animal burrowing during the early Cambrian period.

This is a glossary of terms used in fisheries, fisheries management and fisheries science.

ABISMO is a remotely operated underwater vehicle (ROV) built by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) for exploration of the deep sea. It is the only remaining ROV rated to 11,000-meters, ABISMO is intended to be the permanent replacement for Kaikō, a ROV that was lost at sea in 2003.

Monothalamea is a class of foraminiferans, previously known as Xenophyophorea. Members of this class are multinucleate unicellular organisms found on the ocean floor throughout the world's oceans, at depths of 500 to 10,600 metres. They are a kind of foraminiferan that extracts minerals from their surroundings and uses them to form an exoskeleton known as a test.

J. Frederick Grassle American oceanographer and academic

John Frederick Matthews Grassle was an American marine biologist, oceanographer, professor, and distinguished research scientist, notable for early work on the communities associated with deep-sea hydrothermal vents, and for his involvement in the creation of the Census of Marine Life and the first integration of marine biological data on a global scale, the Ocean Biogeographic Information System.

Robberg Marine Protected Area A marine conservation area around the Robberg peninsula in South Africa

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Agulhas Front Marine Protected Area A marine conservation area off the Eastern Cape in South Africas EEZ

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Benguela Muds Marine Protected Area A marine conservation area off the Western Cape province of South Africa

The Benguela Muds Marine Protected Area is an offshore conservation region on the continental slope of the west coast in the exclusive economic zone of South Africa


International Standard Book Number Unique numeric book identifier

The International Standard Book Number (ISBN) is a numeric commercial book identifier which is intended to be unique. Publishers purchase ISBNs from an affiliate of the International ISBN Agency.