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amphipod: laterally compressed, planktonic or benthic crustaceans

anoxic: without oxygen

aphotic zone: The deep part of the ocean in which sunlight is absent

attenuation: a decrease in the energy of light due to absorption and scattering in the water column


bacteria: single-celled, microscopic prokaryotes

bacterioplankton: planktonic bacteria

BATS: Bermuda Atlantic Time Series Study

BBOP: Bermuda Bio-Optics Program

benthic: pertaining to the sea-floor and the organisms that live there

biogeochemical: short for biological, geological, and chemical; often used to describe cycling of elements in the sea (i.e., biogeochemical cycling)

bioluminescence: the production of light by living organisms. Common among deep-sea creatures

biomass: the number of organisms in an area or volume multiplied by the average weight of the individuals

bio-optics: study of how living organisms (e.g., phytoplankton) affect light  in the sea

bloom: the sudden appearance of a high concentration of phytoplankton resulting from increased reproduction due to favorable conditions

blue-water: refers to open-ocean, oligotrophic conditions


carnivore: an animal that eats other animals

carotenoid: a plant "accessory" pigment that captures sunlight for photosynthesis

chemosynthesis: fixation of carbon from CO2 into organic compounds using energy from oxidation of inorganic compounds such as ammonia, methane, and hydrogen sulfide.  Compare with photosynthesis

chlorophyll: a group of plant pigments that capture sunlight for photosynthesis

cilia: hair-like structures that are used for locomotion, and in some species, for feeding

CO2: carbon dioxide, an important greenhouse gas and part of the carbon cycle

coccolithophorid: small, single-celled phytoplankton that have flagellae and calcareous plates in their cell walls.

cold core ring: a rotating body of water with a relatively cool temperature and high productivity (compare warm core ring)

conductivity: a measure of how well sea water conducts electricity. Conductivity increases with increasing salinity, and is thus used to measure salinity indirectly

copepod: a diverse group of small planktonic, benthic, or parasitic crustaceans that are usually the numerically dominant group of zooplankton  in sea water

crustaceans: a diverse class of primarily aquatic arthropods with a segmented body, paired appendages, and a hard external skeleton. Includes amphipods, copepods, crabs, lobsters, and shrimp.

CTD: acronym that refers to a device used to measure the Conductivity, Temperature, and Depth of sea water

ctenophores: jelly-like zooplankton having 8  rows of cilia for swimming


decomposer: an organism that breaks down dead organic material into inorganic forms

deep scattering layer: a dense layer of marine organisms that reflect sound waves

density: mass per unit volume. The density of sea water is an important physical property that helps control the vertical  and horizontal motion of sea water and ocean currents.

depth profile: a graph that shows how a property of sea water changes with depth

detritus:  debris such as dead organisms, fecal pellets, and mucus products from plankton

diatoms: single-celled  phytoplankton with an external skeleton made of silica

diel: refers to events that occur on a daily or 24-hour cycle

dinoflagellate: single-celled plankton with two flagella, and in some species, an external skeleton made of cellulose

DOC:  abbreviation for dissolved organic carbon

DOM: abbreviation for dissolved organic matter

DON: abbreviation for dissolved organic nitrogen

downwelling: the sinking of water


eddy: a circular swirling of water, a whirlpool

egest: to void  unused food as feces. Commonly known as pooping.

euphausiids: shrimp like, holoplanktonic crustaceans, commonly known as krill. A common food for some whales, seabirds, and fish.

euphotic: refers to the surface layer of the ocean that receives enough sunlight for photosynthesis

eutrophic: refers to ocean regions that have high nutrient concentrations and support a rich food web (compare mesotrophic and oligotrophic)

excretion: the elimination of wastes produced during metabolism, usually as urea or ammonia. Commonly known as peeing.


flagella: hair-like projection used for locomotion in some microorganisms

fluorometer: a device used to measure the fluorescence of phytoplankton chlorophyll; used to determine phytoplankton biomass in the sea

food chain: a linear sequence of organisms in which each is food for the next member in the sequence

food web: a schematic depiction of the feeding interactions in a community

foraminifera: single-celled planktonic or benthic organisms with an external skeleton made of calcium carbonate


gyre: a circular motion of water with a diameter of 1000s of kilometers (larger than an eddy)


halocline: the vertical zone showing the greatest change in salinity with depth

herbivore: an animal that eats plants

holoplankton: planktonic organisms that spend their entire life cycle in the water column (compare meroplankton)

hydrostatic pressure: the pressure exerted at a given depth by the weight of the overlying column of water

hydrowire: a strong cable containing electrical wires that is used to tow or deploy oceanographic research equipment, such as a CTD,  from a ship. The electrical wires allow communication between the ship and the research equipment.


isothermal: of equal temperature. Refers to horizontal or vertical expanses of the ocean containing water of equal temperature


JGOFS: abbreviation for Joint Global Ocean Flux Study. BATS is a component of JGOFS .


krill: euphausids, shrimp like, holoplanktonic crustaceans that provide a common food source for some whales, seabirds, and fish


larvacean:  zooplankton that build mucous "houses" to filter nanoplankton from the water


macroplankton: larger zooplankton between 2 and 20 centimeters in size (compare megaplankton, microplankton, nanoplankton, and picoplankton)

marine snow: aggegrations of detritus, visible to the naked eye, that consist of dead organisms, discarded feeding structures, fecal pellets, and other organic debris

medusa: bell-shaped zooplankton, "jellyfish"

megaplankton: extra-large zooplankton between 20 and 200 centimeters in size (compare macroplankton, microplankton, nanoplankton, and picoplankton)

meroplankton: plankton that spend only part of their  life cycle in the water column before settling to the bottom (compare holoplankton)

mesopelagic zone: the portion of the water column between about 200 and 1000 meters depth

mesotrophic: refers to a region with moderate concentrations of nutrients and moderate biological productivity (compare eutrophic and oligotrophic)

metabolism: the process by which cells oxidize organic materials  to produce energy

micron: a metric unit of length equal to one millionth of a meter

micronutrient: nutrients required by a plant in relatively small concentrations for growth (e.g., iron) , as opposed to macronutrients like nitrate and phosphate which are required in higher concentrations

microplankton: small zooplankton between 20 and 200 microns in size (compare megaplankton, macroplankton, nanoplankton, and picoplankton)

mineralization: the breakdown of organic compounds into inorganic materials

mixed layer: a layer of surface water that is mixed by the wind and is thus isothermal

multicellular: refers to organisms that are made up of more than one cell (compare unicellular)


nanoplankton: extra-small zooplankton between 2 and 20 microns in size (compare megaplankton, macroplankton, microplankton, and picoplankton)

nekton: pelagic animals capable of swimming against a current such as fish and marine mammals

nematocysts: stinging cells on the tentacle of a jellyfish

Niskin bottle: a tube that can be triggered to close and collect water at different depths

nutricline: the vertical zone in the water column where nutrient concentrations increase rapidly with depth

nutrient: organic or inorganic materials used in the nutrition of primary producers


oligotrophic: refers to a region with low concentrations of nutrients and low biological productivity, an ocean "desert" like the Sargasso Sea (compare eutrophic and mesotrophic)

omnivore: an animal that eats both plants and other animals

oxygen minimum layer: a vertical zone in the water column where the concentration of dissolved oxygen gas is low, usually between 400-800 meter deep. .


PAR: abbreviation for Photosynthetically Active Radiation, refers to the wavelengths of sunlight that plants can use to power photosynthesis.

pelagic: refers to the water column and the organisms living there

photophore: the organ in which bioluminescent light is produced

photosynthesis: the process whereby plants use carbon dioxide, water, and energy from sunlight to grow. The process of photosynthesis releases oxygen.

phytoplankton: microscopic, marine planktonic plants such as diatoms that get their energy from sunlight (compare zooplankton)

picoplankton: tiny plankton between 0.2 and 2 microns in size, mostly bacteria (compare megaplankton, macroplankton, microplankton, and nanoplankton)

piscivore: an animal that primarily eats fish

plankton: plants or animals that drift in the water column and are unable to swim against a current

pleuston: marine organisms such as the Portuguese Man oŽ War that float at the sea surface and project partly into the air

POC: an abbreviation for Particulate Organic Carbon

primary production: the amount of organic material that plants synthesize from inorganic substances during photosynthesis

pteropod: a holoplanktonic snail with two swimming "wings"

pycnocline: the vertical zone in the water column where density changes most rapidly with depth



radiolaria: single-celled planktonic organisms that build a skeleton of silica

red tide: a red patch of sea water caused by high concentrations of dinoflagellates, toxins released by the dinoflagellates can make the water poisonous to other marine organisms

respiration: a metabolic process in which cells break down organic materials to produce energy. The opposite of photosynthesis.

ROV: abbreviation for Remotely Operated Vehicle, a submersible robot


salinity: a measure of the saltiness of water

salinometer: a device used to measure salinity

salps: barrel-shaped, gelatinous zooplankton

sink: refers to a region that takes up a greater amount of some substance than it releases. For instance, some ocean areas are carbon sinks, because they absorb more carbon dioxide gas  from the atmosphere than they release back to the atmosphere (compare source).

source: refers to a region that releases more of some substance than it takes up. For instance, some ocean areas are carbon sources, because they release more carbon dioxide gas to the atmosphere than they absorb from the atmosphere (compare sink).

submersible: refers to a vehicle like a submarine or an ROV that is designed to operate underwater


thermocline: the vertical zone in the water column where temperature changes rapidly with depth

time series: a graph that shows how some property or value changes through time

titrator: an instrument that determines the concentration of a substance in a solution by slowly adding a standard reagent of known concentration until a reaction is completed as shown by a color change or electrical measurement

trophic level: the position occupied by an organism in a food chain or a food web


ultraviolet (UV) radiation: invisible wavelengths of light of less than about 380 nanometers (a nanometer equals one-thousandth of a micron)

unicellular: refers to organisms composed of a single cell (compare multicellular)

upwelling: a rising of nutrient-rich water toward the sea surface


veliger: a pelagic, larval stage of some meroplanktonic molluscs (i.e., clams and snails)

vertical migrators: organisms that migrate between deep water and the sea surface on a daily basis


warm core ring: a rotating body of water with a relatively warm temperature and low productivity (compare cold core ring)

water column: refers to a vertical expanse of sea water stretching from the ocean surface to just above  the ocean floor, habitat for pelagic organisms

water mass: a discrete region or volume of sea water that exhibits consistent physical properties such as temperature and salinity. Different water masses tend to mix together very slowly.


zoea: the meroplanktonic larva of a crab

zooplankton:  planktonic animals such as copepods that derive their energy by consuming plants or other animals (compare phytoplankton)



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