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

A
	AAA	Atomic Absorption Analysis.
	AABW	Antarctic Bottom Water.
	AAS	Atomic Absorption Spectroscopy.
	Abiotic	Nonliving (e.g. The chemical, physical and geological factors of an environment). Opposite of biotic.
	Abyssal	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}
	Abyssobenthic	Pertaining to the seabed in the abyssal zone. Found below the bathybenthic zone.
	Abyssopelagic	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 10^15 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.
	ADCP	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.
	Advection	Horizontal or vertical movement of water as a current.
	Aerobic	Life or processes that require, or are not destroyed by, oxygen. Opposite of Anaerobic.
	AFERNOD	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.
	Alvin	American Deep-Sea Research Vehicle. Rated to a depth of 4500m.
	AMS	Accelerator Mass Spectrometry.
	Anaerobic	Life or processes that do not require oxygen, or that are not destroyed by a lack of it. Opposite of aerobic.
	ANOVA	Analysis Of Variance. A statistical technique to compare the means of two or more different groups.
	Anoxic	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.
	Anthropogenic	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.
	Archaea	One of the three primary kingdoms of living organisms comprising methanogenic and sulphur-dependant bacteria.
	Area	The seabed and ocean floor and subsoil thereof, beyond the limits of national jurisdiction.
	ATESEPP	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.
	ATP	Adenosine triphosphate.
	Authority	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.
	Autosub	British Autonomous Underwater Vehicle.
	Autotroph	An organism which synthesizes its own organic material through Chemosynthesis or Photosynthesis. Compare to Heterotroph
	Autotrophic	Pertaining to an Autotroph. Compare to Heterotrophic.
	AUV	Autonomous Underwater Vehicle.
B
	Bacteria	Unicellular prokaryote organisms.
	Bathyal	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.
	Bathybenthic	Pertaining to the seabed in the bathyal zone. Found above the abyssobenthic zone.
	Bathymetry	The study, measurement and charting of water depths.
	Bathypelagic	Referring to the zone of the ocean depths starting at the 10^oC isotherm (100-700m depth depending on localised conditions). Extends down to the 4^oC 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}.
	BBL	Benthic Boundary Layer / Bottom Boundary Layer
	Benthic	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.
	Benthopelagic	Pertaining to the zone very close to, and to some extent having contact with, the seafloor of deeper portions of the open ocean.
	Benthos	Organisms living in, or on, the seabed.
	BGR	Bundesanstalt für Geowissenschaften und Rohstoffe (Federal Institute for Geosciences and Natural Resources). German Geological Survey.
	Bioa