Scientific Glossary

Glossary of terms and abbreviations relevant to the International Seabed Authority and the documents it produces

Please note that this is a constantly evolving document.

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Titlesort descending
Macrobenthos

The macrofauna that is found in the benthic environment. Dominated by polychaetes. Often synonymous with macrofauna.

Macrofauna

Animals which are smaller than 2cm but are retained on a sieve of mesh size 250µm. Positioned in size between the meiofauna andmegafauna. Dominated by polychaetes.

Madeira Abyssal Plain

An abyssal plain in the Atlantic Ocean, approximately 1000km west of North Africa. It is approximately 5400m deep. Abbreviated to MAP.

Magma

Molten rock below the Earth's surface.

Manganese Nodule

Synonymous with polymetallic nodule.

MAP

Madeira Abyssal Plain.

MAST

Marine Science and Technology (EU programme).

Mega Core

Sample taken with a mega corer.

Mega Corer

A larger version of the multi corer capable of sampling macrofauna in addition to meiofauna and microfauna. Takes a smaller sample than the box corer but there is less disturbance of the surface sediment.

Megabenthos

The megafauna that is found in the benthic environment. Often synonymous with megafauna.

Megafauna

Defined as animals larger than 2cm. These animals can be observed from photographs. The largest size class of animals. Comprised of errant and sessile organisms.

Meiobenthos

The meiofauna that is found in the benthic environment. Dominated by the nematoda and benthic copepoda. Often synonymous withmeiofauna.

Meiofauna

Animals that are intermediate in size between macrofauna and microfauna. Operationally defined as organisms which pass through a sieve of mesh size 250µm but are retained on a mesh size of 32µm. Dominated by the foraminifera, copepoda and nematoda.

Meroplankton

Temporary members of the plankton, usually during their early life stages, but not as adults. Compare to holoplankton.

Mesopelagic

Referring to the portion of the oceanic province that is below the epipelagic and above the bathypelagic, usually corresponding to the dimly lit ocean or "twilight zone". This zone contains an oxygen minimum zone and usually the maximum concentrations of the nutrients nitrate and phosphate. {Figure}.

Metazoan

Multicelled animals.

Meteorological

Pertaining to meteorology.

Meteorology

The science and study of the physics, chemistry, and dynamics of the Earth's atmosphere, especially weather and climate.

Micro-organism

Microscopic organisms including bacteria, archaea and microscopic eukaryotes.

Microbenthos

The microfauna that is found in the benthic environment. Often synonymous with microfauna.

Microbial

Pertaining to microbes.

Microfauna

Organisms invisible to the naked eye, smaller than meiofauna. Operationally defined as organisms which pass through a sieve of mesh size 32µm.

Mid-Ocean Ridge

A bilaterally symmetrical submarine ridge with sloping sides produced as two tectonic plates move apart from each other. Almost always associated with hydrothermal activity and the formation of polymetallic sulphides.

Mini Core

Sample taken with a mini corer.

Mini Corer

A smaller version of the multi corer.

Mir I

Russian Deep-Sea Research Vehicle. Rated to a depth of 6000m. Sister vessel of Mir II.

Mir II

Russian Deep-Sea Research Vehicle. Rated to a depth of 6000m. Sister vessel of Mir I.

Molecular Operational Taxonomic Unit

A taxonomic unit defined using the DNA of an organism rather than it's morphology. Ideally it is at the species level. Abbreviated toMOTU.

Morphological

Pertaining to morphology.

Morphology

Form and structural features. Can be used to describe organisms and geological features amongst other things.

Motility

The ability to move.

MOTU

Molecular Operational Taxonomic Unit.

Multi Core

Sample taken with a multi corer.

Multi Corer

A quantitative sediment sampling device suitable for sampling soft sediment. Less disturbance of the surface sediment than a box corer. Takes simultaneous tube core samples to a depth of up to approximately 30cm. Most often used for sampling meiofauna andmicrofauna. Also used for chemical sampling of soft sediment. Also called a multiple corer. Smaller and larger versions sometimes called a mini corer and mega corer respectively.

Multiple Corer

Synonymous with multi corer.