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 and any comments or appropriate images should be sent to Dr Adam Cook


A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z






Atomic Absorption Analysis.



Antarctic Bottom Water.



Atomic Absorption Spectroscopy.



Nonliving (e.g. The chemical, physical and geological factors of an environment).  Opposite of biotic.



The deep-sea. The upper boundary has been defined as anywhere between 1000m and 4000m, the lower boundary usually considered to be 6000m.


Abyssal Plain

The deep ocean floor with a gradient of less than 1:1000 (approximately 0.05°). Extends seaward from the Continental Rise. {Figure}



Pertaining to the seabed in the abyssal zone.  Found below the bathybenthic zone.



Referring to the majority of the deep-sea open ocean.  It is separated from the overlying bathypelagic by the 4 C isotherm and from the underlying hadopelagic at about 6000 meters.  {Figure}.


Accelerator Mass Spectrometry

An ultra sensitive quantitative technique for measuring isotopic ratios. It is typically used for determining the ratio of the abundant to rare isotopes of certain elements.  Can measure ratios as low as 1 in 1015 for carbon.  Its advantages include using small samples, fast analysis time and it is far more sensitive than all other mass spectrometry techniques.  Abbreviated to AMS.


Acoustic Doppler Current Profiler

An instrument used to measure ocean currents. It transmits high frequency acoustic signals which are backscattered from plankton, suspended sediment, and bubbles, all of which are assumed to be traveling with the mean speed of the water. The Doppler shift in the backscatter echo allows the water velocity to be determined.  Usually abbreviated to ADCP.


Active Sulphides

Polymetallic sulphides through which warm water is flowing.  Active sulphides deliver reduced compounds (e.g., sulphide) to the seafloor-seawater interface where they can be oxidized or otherwise autotrophically metabolized by free-living or symbiotic micro-organisms.  Synonymous with hydrothermal vents.  Opposite of Inactive Sulphides.



Acoustic Doppler Current Profiler.


Adenosine Triphosphate

A complex organic compound which serves for short-term energy storage and conversion in all organisms. Usually abbreviated to ATP.  The amount of ATP present can be used as a measure of total microbial biomass in the sediment, as it corresponds to the number of active cells, most of which are bacteria.



Horizontal or vertical movement of water as a current.



Life or processes that require, or are not destroyed by, oxygen.  Opposite of Anaerobic.



Association française pour l’exploration et la recherche des nodules (French Association for Exploration and Research of Nodules). One of the groups (along with IFREMER) granted a contract for the exploration of polymetallic nodules. Other contractors listed here.


Agassiz Trawl

Qualitative sampling device used to sample large numbers of the megabenthos and benthopelagic fauna  It is a double sided trawl adapted from the fishing gear of coastal fishermen.  Named after the American naturalist Alexander Agassiz.  Also called the Blake trawl or Sigsbee trawl (the name of the ship used by Alexander Agassiz and the captain of that ship respectively).


Alien Species

Synonymous with Invasive Species.



American Deep-Sea Research Vehicle.  Rated to a depth of 4500m.



Accelerator Mass Spectrometry.



Life or processes that do not require oxygen, or that are not destroyed by a lack of it.  Opposite of aerobic.



Analysis Of Variance.  A statistical technique to compare the means of two or more different groups.



Without oxygen.  Compare to Oxic and Hypoxic.


Antarctic Bottom Water

The densest water in the oceans formed around Antarctica.  Has a temperature of approximately -0.4°C and salinity of approximately 34.66‰.  Abbreviated to AABW.



Caused by, or as a result of, human activity.


Aphotic Zone

The deeper regions of the water column where there is insufficient light for photosynthesis to occur.  Compare to Euphotic Zone.



One of the three primary kingdoms of living organisms comprising methanogenic and sulphur-dependant bacteria.



The seabed and ocean floor and subsoil thereof, beyond the limits of national jurisdiction.



Auswirkungen technischer Eingriffe in das Ökosystem der Tiefsee im Süd-Ost-Pazifik vor Peru (Impacts of potential technical interventions on the deep-sea ecosystem in the Southeast Pacific) (German programme)


Atomic Absorption Analysis

Synonymous with Atomic Absorption Spectroscopy.  Abbreviated to AAA.


Atomic Absorption Spectroscopy

A quantitative analytical method for determining the presence, and concentration, of metals in liquid samples.  Can detect concentrations as low as 100ppb.  Abbreviated to AAS.



Adenosine triphosphate.



Abbreviation of International Seabed Authority


Autonomous Undersea Vehicle

Synonymous with Autonomous Underwater Vehicle.


Autonomous Underwater Vehicle

Unmanned, untethered research submersible that can work autonomously once programmed with certain criteria.  Abbreviated to AUV.  For example, Autosub and Epaulard.  Compare to Remotely Operated Vehicles and Deep-Sea Research Vehicles.



British Autonomous Underwater Vehicle.





An organism which synthesizes its own organic material through Chemosynthesis or Photosynthesis.  Compare to Heterotroph



Pertaining to an Autotroph.  Compare to Heterotrophic.



Autonomous Underwater Vehicle.




Unicellular prokaryote organisms.



The deep-sea from the edge of the continental shelf (approximately 200m) down to the abyssal zone (1000-4000m depending on definition).  Corresponds to the continental slope.



Pertaining to the seabed in the bathyal zone. Found above the abyssobenthic zone.



The study, measurement and charting of water depths.



Referring to the zone of the ocean depths starting at the 10oC isotherm (100-700m depth depending on localised conditions). Extends down to the 4oC isotherm (approximately 2500m).  There is no light source other than bioluminescence, temperature is uniformly low, and pressures are great. Found between the mesopelagic and abyssopelagic.  {Figure}.



Benthic Boundary Layer / Bottom Boundary Layer



Pertaining to the seabed. Divided into distinct depth regions including the bathybenthic and abyssobenthic zones. 


Benthic Boundary Layer

The layer of water immediately above the seabed extending from ten to several hundred metres above the seabed. Synonymous with Bottom Boundary Layer.  Abbreviated to BBL


Benthic Impact Experiment

An experiment carried out in situ in the marine environment to determine the impact a certain activity, such as mining, may have on the seabed.  Abbreviated to BIE.


Benthic Plume

A stream of water containing suspended particles produced as a result of disturbance of the seafloor which spreads in a zone close to the seabed.  Compare to surface plume and rain of fines.



Pertaining to the zone very close to, and to some extent having contact with, the seafloor of deeper portions of the open ocean.



Organisms living in, or on, the seabed.



Bundesanstalt für Geowissenschaften und Rohstoffe (Federal Institute for Geosciences and Natural Resources). German Geological Survey.



The accumulation of chemical substances from the environment within biological organisms.  Results in higher concentrations of the bioaccumulated chemicals within the organism than in the surrounding medium.



Benthic Impact Experiment.



Contraction of the term “biological diversity”.  The variety of life in all its forms, levels and combinations. Includes ecosystem diversity, species diversity, and genetic diversity.


Biogeochemical Cycle

The cyclic transformation of chemicals through interacting biological, geological and chemical processes.



The study of geographical distributions of organisms, their habitats and the environmental or historical factors that produce them.


Biological Diversity

Synonymous with biodiversity.



The mass of one or more species in a given area.



All of the plant and animal life of a particular region.



Pertaining to life or living organisms.  Opposite of abiotic



The rearrangement of sediments by organisms as they burrow through or ingest them.


Black Smoker

Hydrothermal vent with a higher temperature (>350oC) than found at white smokers.  Usually characterized by chalcopyrite and anhydrite deposits.  The deposit and mineral rich water plume is dark in colour, hence the name.


Blake Trawl

Synonymous with Agassiz trawl but named after the ship used by Alexander Agassiz.  Also called the Sigsbee trawl.


Bottom Boundary Layer

Synonymous with Benthic Boundary Layer.  Abbreviated to BBL


Box Core

Sample taken with a box corer.


Box Corer

A relatively large, robust, quantitative sediment sampling device suitable for sampling a wide range of sediment types.  Penetrates up to 50cm into the seabed using its own weight.  Most often used for sampling macrofauna.  An adaptation of the box core is the vegematic box corer.






Composed of calcium carbonate (CaCO3)..


Calcite Compensation Depth

Synonymous with Calcium Carbonate Compensation Depth.


Calcium Carbonate Compensation Depth

The depth at which Calcium Carbonate (CaCO3) dissolves.  Below this depth calcium carbonate deposits are not found.  Also called Calcite Compensation Depth and Carbonate Compensation Depth.  Abbreviated to CCD.


Carbonate Compensation Depth

Synonymous with Calcium Carbonate Compensation Depth.



An organism that feeds on flesh.  Compare to herbivore.



Calcium Carbonate Compensation Depth.



Clarion-Clipperton Fracture Zone.



Clarion-Clipperton Zone.



Colony-Forming Unit..



Pertaining to chemoautotrophy. Synonymous with chemotrophic.  Compare to photoautotrophic.



Synonymous with chemosynthesis.



The biological synthesis of organic material using chemical reactions as an energy source.  Microorganisms metabolically transform inorganic carbon to organic carbon (cells) using energy derived from oxidation of reduced compounds.  Chemosynthesis is the basis for the food web associated with deep-sea hydrothermal vents.  Compare to photosynthesis.  Synonymous with chemoautotrophy.



Pertaining to chemosynthesis.  Compare to photosynthetic.



Synonymous with chemoautotrophic.



The green pigment in plants that absorbs energy for photosynthesis.      



Carbon, Hydrogen and Nitrogen


Clarion-Clipperton Fracture Zone

An area in the Eastern Pacific Ocean approximately 20oN, 120oW to 5oN, 160oW bounded by the Clarion Fracture Zone to the north and the Clipperton Fracture Zone to the south.  All of the potential polymetallic nodule exploration contracts that have been granted in the Pacific are in this region. Also called the Clarion-Clipperton Zone.  Abbreviated to CCFZ or CCZ.


Clarion-Clipperton Zone

Synonymous with Clarion-Clipperton Fracture Zone.  Abbreviated to CCZ.



An intermediate level of taxonomic classification containing one or more Orders forming a subgroup of a Phylum.


Cobalt Crust

Hydroxide/oxide deposit of cobalt-rich iron/manganese (ferromanganese) crust formed from direct precipitation of minerals from seawater onto hard substrates in the deep sea on features with significant topographic relief, such as seamounts and ridges.  Contain minor but significant concentrations of cobalt, titanium, nickel, platinum, molybdenum, tellurium, cerium, other metallic and rare earth elements.  Synonymous with cobalt-enriched crust.


Cobalt-enriched crust

Synonymous with cobalt crust.


Colony-Forming Unit

A unit of measurement for fungal or bacteria samples.  Abbreviated to CFU.



China Ocean Mineral Resources Research and Development Association.  One of the groups granted a contract for the exploration of polymetallic nodules. Other contractors listed here


Continental Rise

The gently sloping seabed from the edge of the Continental Slope to the Abyssal Plain.  An average gradient of approximately 1:50 (approximately 1°).  {Figure}.


Continental Shelf

The shallow seabed extending from the part of the shore permanently submerged down to the Continental Slope (typically 100-200m depth).  Gradient usually less than 1:100 (approximately 0.5°).  {Figure}.


Continental Slope

The steeply sloping seabed from the Continental Shelf down to the Continental Rise.  Gradient ranging from 1:3 to 1:20 (approximately 2.5-20°).  {Figure}.



The groups granted a contract by the International Seabed Authority for the exploration of polymetallic nodules. The various contractors include AFERNOD/IFREMER, COMRA, DORD, IOM, KORDI, the Government of India and the Government of Korea.



Synonymous with Copepoda.



Small planktonic, benthic or parasitic crustaceans.  Planktonic forms are usually the numerically dominant group within the zooplankton.  Synonymous with copepod.




Cosmopolitan Species

Species which are widely distributed.



Commonwealth Scientific and Industrial Research Organization



Pertaining to a system for measuring Conductivity (a measurement of salinity), Temperature and Depth (determined from pressure measurements).  Additional parameters, such as pH and dissolved oxygen concentration, can be measured if optional sensors are installed.  Often has Niskin bottles attached for taking water samples at specific depths.




Cumulative Impacts

Impacts resulting from incremental changes caused by other past, present or foreseeable actions.  Compare to direct impacts.




DISCOL Experimental Area.


Deep-Sea Research Vehicle

Manned research submersible used for sampling and observation of the deep sea.  Abbreviated to DSRV.  Examples include Alvin (USA), Nautile (France), Mir I & Mir II (Russia) and Shinkai 6500 (Japan).  Compare to Autonomous Underwater Vehicles and Remotely Operated Vehicles.



Organisms living at or near the bottom of a body of water. Synonymous with epibenthic.



To change the structure of a molecule, disrupting its biological activity.



Something that denatures an organic molecule.


Denaturing Gradient Gel Electrophoresis

A method for separating DNA fragments using their variable motility on a gradient of denaturing conditions.  A method for separating species using their DNA.  Abbreviated to DGGE.


Deoxyribonucleic Acid

Molecules found in most organisms that carry genetic information necessary for the organization and functioning of most living cells.  Also responsible for inherited characteristics.  Abbreviated to DNA.  Compare to Ribonucleic Acid (RNA).


Deposit Feeder

Synonymous with detritovore.


Deposit Feeding

The action of feeding on detritus by either ingesting material unselectively and excreting unusable components or by selectively ingesting discrete particles.



Organism that feeds on detritus. Synonymous with Deposit Feeder.



Dead organic matter from both plant and animal origin.



Denaturing Gradient Gel Electrophoresis.



Involving a 24-hour period that includes a day and the adjoining night.


Direct Impacts

Impacts caused as a direct result of an action that is identified by the absence of an existing structure with an evident change in the environment and with future consequences of the action.  Compare to cumulative impacts.



Disturbance and Recolonization (German project in Pacific Ocean).



Processes which are completed within approximately 24 hours and recur every 24 hours.



Deoxyribonucleic Acid.



Dissolved Oxygen



Dissolved Organic Carbon.



Department of Ocean Development (India)



Dissolved Organic Matter.



Deep Ocean Mining Environmental Study (United States)



Deep Ocean Resources Development Co., Ltd. (Japan).  One of the groups granted a contract for the exploration of polymetallic nodules. Other contractors listed here.


Dormant Sulphides

Synonymous with inactive sulphides.



Deep-Sea Research Vehicle.




The study of the physical and biological interactions between an organism and its natural environment.



The living (biotic) and non-living (abiotic) components of an environment that interact.


Ecosystem Diversity

The diversity of biological communities and their chemical and physical environment. The highest level of biodiversity. Compare to species diversity and genetic diversity.



Environmental Impact Assessment.



Environmental Impact Studies and Equipment Tests (COMRA project)



The blood and tissues of fish contain dissolved gases. If fish from the deep ocean are brought to the surface, the decrease in pressure allows the dissolved gas to expand in the form of bubbles (embolism), causing disfiguration and protrusion of the internal organs through the mouth and other orifices.



An organism that might be geographically widespread, but is restricted to a specific habitat or region.



The degree to which a species is restricted to a particular geographic region; endemism usually occurs in areas that are isolated in some way.



Synonymous with infauna



A symbiotic relationship where the symbiont is found within the tissues of the host (e.g., bacteria living inside tubeworms, clams or mussels)



Environmental Quality Department (Massachusetts, United States)



All of the physical, chemical, and biological factors in the area where a plant or animal lives.



Pertaining to the environment.


Environmental Impact Assessment

A detailed study and analysis of the effects that a potential action (such as deep sea mining in a particular area) may have on the environment.  Abbreviated to EIA.



French Autonomous Underwater Vehicle.



Synonymous with demersal


Epibenthic Sled

A qualitative sampling device which is dragged along the seabed.  It is comprised of a flattened mesh bag attached to wide runners to prevent it sinking into the sediment.  Designed to collect the smaller organisms at the sediment-water interface.



Animals that live on the seabed, either attached to the seafloor or freely moving over it.



Pertaining to the epifauna



Referring to the upper region of the ocean depths, above the mesopelagic, where photosynthesis can occur.  Extends from the surface down to 100-200m depending on the localized conditions. Also called the Euphotic Zone.  {Figure}.



A symbiotic relationship where the symbiont is found living on the outside of the host (e.g., bacteria living on the surface of bresiliid shrimp or alvinellid polychaetes).



Equatorial Pacific (Ocean).



Used to describe the large, active megafauna.  Dominated by the Echinodermata, Arthropoda and Fishes.  Opposite of sessile.



European Union.



All organisms except viruses, bacteria and blue-green algae.  They have a distinct nuclear membrane surrounding the nucleus and contain chromosomes. Compare to prokaryote.


Eularian Measurement

Measurement of the motion of a fluid by monitoring flow past a fixed point.  Compare to Lagrangian measurements.


Euphotic Zone

The upper section of the ocean that receives sufficient light for photosynthesis. In clear oceanic waters, the euphotic zone can extend to a maximum water depth of 200m. Synonymous with epipelagic.  Compare to Aphotic Zone



Able to tolerate a wide range in depth.  Opposite of stenobathic.  Compare to euryhaline and eurythermic



Able to tolerate a wide range in salinity.  Opposite of stenohaline.  Compare to eurybathic and eurythermic



Able to tolerate a wide range in temperature.  Opposite of stenothermic.  Compare to eurybathic and euryhaline.



High nutrient concentrations supporting high productivity.  Compare to oligotrophic.



The skeleton or supporting structure, on the outside of an organism.


Expendable Bathythermograph

A weighted probe dropped into the sea that transmits temperature readings as it falls through the water column to produce graphs of temperature against depth.  The probe is not recovered.  Abbreviated to XBT.


Expendable CTD Probe

A weighted CTD probe dropped into the sea that transmits readings as it falls through the water column to produce graphs of conductivity (a measurement of salinity) and temperature against depth.  The probe is not recovered.  Used when the use of normal CTD apparatus is not practical.  Abbreviated to XCTD.



The recovery for commercial purposes of mineral deposits in the Area and the extraction of minerals therefrom, including the construction and operation of mining, processing and transportation systems, for the production and marketing of metals.  Compare to exploration and prospecting.



Searching for mineral deposits in the Area with exclusive rights, the analysis of such deposits, the use and testing of recovery systems and equipment, processing facilities and transportation systems, and the carrying out of studies of the environmental, technical, economic, commercial and other appropriate factors that must be taken into account in exploitation.  Compare to exploitation and prospecting.



A species which still occurs.  Opposite of extinct. 



A species  that no longer occurs anywhere in the world.  Opposite of extant.  Compare to extirpated.



A species  that no longer occurs in a specific location or region.  Compare to extinct.




An intermediate level of taxonomic classification containing one or more Genera forming a subgroup of an Order.



Animals, especially those found in a specific region.  Compare to flora.



Pertaining to the fauna.


Ferromanganese Nodule

Synonymous with polymetallic nodule.



Free-Fall Grab.


Filter Feeder

An organism that feeds by filtering particulate organic matter from the surrounding water.  Synonymous with suspension feeder.


Filter Feeding

The action of feeding by filtering particulate organic matter from the surrounding water.   Synonymous with suspension feeding.