The marine biology dredge is used to sample

organism In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and ...

s living on a rocky bottom or burrowing within the smooth muddy floor of the

ocean The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the wo ...

(

benthic 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. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

) 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. 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Azoic hypothesis The Azoic hypothesis (sometimes referred to as the Abyssus theory) is a superseded scientific theory proposed by Edward Forbes in 1843, stating that the abundance and variety of marine life decreased with increasing depth and, by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 h ...

. Later samplers devised by Howard L. Sanders and the

Epibenthic sled An epibenthic sled (or ''epibenthos sled/sledge'') 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 sinkin ...

History

The first marine biology dredge was designed by

Otto Friedrich Müller Otto Friedrich Müller, also known as Otto Friedrich Mueller (2 November 1730 – 26 December 1784) was a Danish naturalist and scientific illustrator. Biography Müller was born in Copenhagen. He was educated for the church, became tutor to a yo ...

and in 1830 the results of two dredging expeditions undertaken by

Henri Milne-Edwards Henri Milne-Edwards (23 October 1800 – 29 July 1885) was an eminent French zoologist. Biography Henri Milne-Edwards was the 27th child of William Edwards, an English planter and colonel of the militia in Jamaica and Elisabeth Vaux, a Frenchw ...

and his friend

Jean Victoire Audouin Jean Victor Audouin (27 April 1797 – 9 November 1841), sometimes Victor Audouin, was a French natural history, naturalist, an entomologist, Herpetology, herpetologist, ornithologist, and malacologist. Biography Audouin was born in Paris and was ...

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. 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 The British Science Association (BSA) is a charity and learned society founded in 1831 to aid in the promotion and development of science. Until 2009 it was known as the British Association for the Advancement of Science (BA). The current Chie ...

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 The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Edward Forbes Edward Forbes FRS, FGS (12 February 1815 – 18 November 1854) was a Manx naturalist. In 1846, he proposed that the distributions of montane plants and animals had been compressed downslope, and some oceanic islands connected to the mainlan ...

. 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. 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.

Gallery

File:ChallengerShallowDredge.jpg, Deep-water dredge – ''Challenger'' expedition File:Albatross-ii.jpg, – Dredges were an important research tool on this marine research vessel File:Marine ecologists.jpg, Marine ecologists aboard a research ship and next to a dredge winch File:Specimen plate of benthic invertebrates collected via dredge sampling on the IIOE-2 expeditions of 2017-2018 - Oo 621473.png, Specimens of benthic invertebrates collected via dredge sampling during research expeditions in the Indian Ocean

References

*Anastasios Eleftheriou and Alasdair McIntyre, 2005 ''Methods for the Study of Marine Benthos'', Third Edition *McIntyre, A.D., Elliot, J.M., and Ellis, D.V. 1984. Introduction: Design of sampling programmes. In: ''Methods for the study of marine benthos'' (N.A. Holme and A.D. McIntyre, eds.), pages 1–26. Blackwell Scientific, Oxford.. *Forster, G. R. 1953 A New Dredge for Collecting Burrowing Animals ''Journal of the

Marine Biological Association The Marine Biological Association of the United Kingdom (MBA) is a learned society with a scientific laboratory that undertakes research in marine biology. The organisation was founded in 1884 and has been based in Plymouth since the Citadel H ...

'' (1953), 32 :193-198. *Helen M. Rozwadowski, 2008 ''Fathoming the Ocean:The Discovery and Exploration of the Deep Sea'' Harvard University Press

External links

{{Wikisource, 1911 Encyclopædia Britannica/Dredge and Dredging
The Norman Holme Archive John J. Dickinson and Andrew G. Carey, Jr.A comparison of two benthic infaunal samplers ASLO Vol 20 issue 5
Marine biology

History

Gallery

See also

References

External links