‘a’ā is a type of lava flow identified by the characteristic rough, jagged and clinkery surface texture.

Photo: USGS

Photo: USGS


Airborne Radar Sounder:

An instrument that uses radio-echo sounding to determine ice thickness. It is attached to the bottom of an airborne vehicle and measures ice-thickness below the instrument. This is a costly method with 3-D spacial limitations.

Anadromous fish:

Fish that spent the majority of their life in the ocean but migrate via rivers into freshwater to spawn. Young develop in freshwater before returning to the marine environment as adults. Examples include salmon, shad, river herring, and striped bass.


Aquaculture is the cultivation of aquatic organisms under controlled conditions. The purpose is to increase fish harvest to satisfy demand. Aquaculture started 4,000 years ago in China. In 1987 and 2000 the global aquaculture product of fish (including shellfish) was 4 million and 14 million, respectively. In 2005, 2% of the fish consumed in the United States was from aquaculture. Species are good candidates for aquaculture if they reproduce easily in captivity, the juvenile population is able to survive in controlled conditions and gain weight rapidly eating cheap and available food, and they will yield a high market price.

Sverdrup, K.A., Duxbury, A.C., and Duxbury, A.B. (2005) An introduction to the world’s oceans. New York, NY: McGraw Hill Co.


Growth by gradual accumulation or deposition of layers.


The process by which a region becomes drier than normal seasonal variation as described by a reduction in soil moisture, precipitation,  and atmospheric water vapor, often attributed to climate change. This can lead to desertification, which is the expansion of desert biomes due to the dryness. (http://en.wikipedia.org/wiki/Aridification)

Beckman-Coulter Counter:

An instrument used to count and measure the size of particles suspended in an electrolyte fluid, such as water, by detecting changes in electrical resistance. This counter is often used to measure cells (bacteria, phytoplankton, etc.) and suspended sediment. https://www.beckmancoulter.com

Benthic (a.k.a demersal):

Pertaining to the bottom of the ocean, or the seafloor. Fish species may be categorized as “demersal” -even those that swim through the water column- if their diet consists primarily of benthic organisms. Examples of demersal fish species include flounder and most hake species.


The process that leads to accumulation of pollutants over time in the fatty tissue, or lipids, of living things. The primary chemicals that tend to bioaccumulate are persistent organic pollutants because they dissolved easily in fatty tissues and are not easily metabolized in the body.


How diverse an ecosystem is with regards to how many different organisms are present in a given environment at a given time.


The attachment of an organism or multiple organisms to a surface that is in contact with water for a period of time (think of barnacles and algae, or “scum” if you will…, attaching to the bottom of a boat in the water).  More here.


When the concentration of a compound is higher in a predator than in its prey, the compound is said to biomagnify. This process is important for many bioaccumulative pollutants, and causes them to concentrate at high levels in top predators.


When an organism ingests a compound and then that compound is modified due to biological processes, this is called biotransformation. Many pollutants are transformed into different compounds when they are metabolized. Naturally-occurring toxins like ciguatoxins can be transformed into more potent poisons as they accumulate in the bodies of fish.

Coral Bleaching:

This phenomenon occurs when corals lose the plant cell tissue living inside them, known as the zooxanthellae. The zooxanthellae have a symbiotic relationship with the coral, helping the coral to photosynthesize, while the corals produce carbon dioxide for the zooxanthellae. Coral bleaching is seen when corals become “bleached” or turn white and is caused when corals become stressed. This happens when they get too much light, when they receive high fluctuations in water temperature, or even if there are higher than normal levels of contaminants in the water. (More here)

Coriolis force:

An apparent force caused by the rotation of the Earth. It causes objects moving in the northern hemisphere to be deflected to the right and objects in the southern hemisphere to be deflected to the left.


Mysterious or obscure.


Rings of air that spin counterclockwise or clockwise around a low or high pressure center

Demersal: (a.k.a benthic):

Pertaining to the bottom of the ocean, or the seafloor. Fish species may be categorized as “demersal” -even those that swim through the water column- if their diet consists primarily of benthic organisms. Examples of demersal fish species include flounder and most hake species.


The settling of broken down earth materials that have been eroded and then transported by wind, water, gravity, ice, etc. Deposition of material depends on the transport energy and grain size.

Effusive Lave Flow:

A non-explosive eruption with lava acting like a thick, sticky liquid.

Ekman Transport:

The net movement of surface water perpendicular to the wind direction. The movement of surface water is driven by the frictional forces of wind acting on the surface of the ocean and the Coriolis force; an apparent force due to the rotation of the Earth, with deflection to the right in the Northern hemisphere and to the left in the Southern Hemisphere.


The break down and removal of earth material by external forces. Erosion is mechanical if it is driven by the effects of wind, water, gravity, and freeze-thaw for example, or chemical erosion if the break down is from chemical reactions.


The aquatic area where a river meets the ocean


Eutrophication simply describes a marine environment where there are high levels of production because of high inputs of nutrients, whether natural or human-produced. Run-off from agriculture as well as wastewater treatment plants are common sources of nutrient-laden water to coastal environments. These nutrient-rich conditions can be problematic by causing algal blooms and hypoxic conditions (low oxygen). While we commonly think of nutrients entering the environment through rivers and wastewaters, scientists now know that nutrients reach the open ocean and other remote areas via the atmosphere. Even slightly elevated inputs of nutrients can have a significant effect in these nutrient-poor environments. Learn more at the World Resources Institute and the Encyclopedia of Earth.


The total sum of water vapor released to the atmosphere by the processes of evaporation and transpiration. Evaporation is the physical process in which liquid water is becomes a gas, moving from the Earth’s surface into the atmosphere. Transpiration is the biotic process in which plants release water vapor into the atmosphere. (http://ga.water.usgs.gov/edu/watercycleevapotranspiration.html)

Fast ice:

from Pilford et al. 2013: thick (>120 cm) annual fast ice .

Fisheries Genetics:

Fisheries genetics refers to the application of genetic principles and methods to answer fisheries-related questions. It can deal with species identification, breeding in aquaculture, management of fish stocks and traceability of fish and fish products.


Fractionation occurs when a process, either biological or physical, changes the balance of an isotope in a natural system. For example, during photosynthesis, plants have a preference to uptake carbon-12 over carbon-13; thus the plants can be depleted in carbon-13 compared to carbon-12 from the environment’s natural equilibrium.

Genetic Diversity:

Genetic diversity is the variety of genes found in a population or between populations of a single species. The higher the genetic diversity within a species, the higher the chance the species has for adaptation and survival.

Global Distillation:

Global distillation, or the Grasshopper Effect, describes how persistent semi-volatile pollutants (compounds that vaporize and condense depending on temperature) travel from industrial centers like the US, which are located at mid-latitudes and are responsible for the production of most pollution, up to polar regions. Pollutants are carried toward colder polar regions through sequential cycles of evaporation and deposition due to prevailing winds and seasonal changes in temperature. This process is of great concern to scientists because polar regions are home to fragile, valuable ecosystems. The accumulation of contaminants in these places poses a threat to wildlife and native people.


The process of going out to the field to verify remote sensing measurements and observations. For example, you may see a house in Google Earth. If you were to “ground-truth” the satellite imagery data from Google Earth, you would go to the address in person to see if that house still exists.
Mission Ground Truth

Half Spreading Rate:

The rate of movement on one side of a mid-ocean ridge. It is calculated as the distance moved over time. The value of half spreading rate multiplied by 2 yields the full spreading rate for both sides of a ridge.


Literally translates into “scared of water.” Hydrophobic compounds are more likely to dissolve in materials like fatty tissue, particulate matter, or plastic than in water, so they tend to move out of water and into these substances. (More here)

Impervious Surfaces:

A material that does not allow liquids to pass through it. This term is commonly applied to roads and concrete. These surfaces prevent rain from being absorbed by the soil; instead, water is kept on the surface, and is often attributed to nuisance flooding and run-off into many water bodies.

Interdecadal Pacific Oscillation (IPO):

A pattern of climate variability with characteristic positive and negative phases, similar to how the El Nino Southern Oscillation has a positive phase (El Nino) and a negative phase (La Nina). Positive IPO is characterized by warm tropical Pacific surface ocean temperatures and weakened trade winds, whereas the negative IPO phase is characterized by cooler tropical Pacific surface ocean temperatures and strengthened trade winds. The typical duration of each phase can last two decades, and has been linked with variability in the global mean surface air temperature. Currently, we are experiencing a negative phase of IPO, with cooler global mean surface air temperatures which have dominated since 2001.

Intertidal Zone:

The area on a beach that is covered by water only at high tide.

Iron Fertilization:

The addition of iron, a limiting micronutrient, to the surface ocean. Phytoplankton living surface waters that are deficient in iron bloom due to the addition, which is utilized during photosynthesis. A large scale bloom can remove carbon dioxide from the atmosphere, since carbon dioxide is required for photosynthesis. Iron fertilization of the surface ocean has been proposed as a method of slowing climate change by removing anthropogenically sourced carbon dioxide from the atmosphere, as carbon dioxide is a greenhouse gas responsible for climatic warming.


An isotope is the various forms of an element that has the same amount of protons, but varying numbers of neutrons, in the atom’s nucleus. The different neutron amounts do not alter the chemical identity of that element. An example is nitrogen, which naturally occurs as nitrogen-14 (7 neutrons) and nitrogen-15 (8 neutrons). Isotopes can be stable (will not decay) or radioactive.

Jet Stream:

A strong air current that acts as a barrier of wind flowing from west to east that retreats towards the North Pole in the summer.

Keystone Species:

This refers to a species whose existence plays a crucial role in their community structure. They have a proportionately large influence on the stability of their ecosystem and without the keystone species existence, their community is thrown off balance. (More here).


A well hidden resting place.


LiDAR is a remote sensing technology that measures distance by illuminating a target with a laser and analyzing the reflected light. It is a technology popularly used as a technology for making high-resolution maps.

Limiting Nutrient:

Organisms like phytoplankton need various nutrients to grow, and they will continue to grow and survive as long as long as there are more nutrients remaining in the water. A limiting nutrient is whichever nutrient is available in the shortest supply, as this nutrient is responsible for limiting growth in the system – if this one nutrient is low, it doesn’t matter whether other nutrients are available in excess – growth will be limited at a low level and will increase only when inputs of the limiting nutrient increase.

Marine Protected Area:

Regions in which human activities are under some restrictions in the interest of protecting the natural environment and any cultural or historical resources.
(More here).


Tiny fragments and pieces of plastic in the size range of millimeters. Common sources include nurdles (small industrial plastic pellets), microbeads from personal care products, and synthetic fibers found in textiles.


The ratio of the number of births to the size of the population.

Neap Tide:

Least difference observed between the high and low tides, the sun and moon gravitational forces are opposing each other, this occurring during the first and third quarter of the moon phases.

Neutral genetic markers:

markers for which changes or mutations in this region of the DNA will not change the ability of the organism to survive and reproduce.

Ocean Acidification:

The dissolution of atmospheric carbon dioxide into our oceans lowers pH by dissociation of carbonic acid. Ocean acidification is the reduction in ocean pH as a consequence of increasing anthropogenic inputs of carbon dioxide to our atmosphere.

Ore Deposit:

Ore deposit is a general term describing a useful commodity that is sufficiently concentrated in an accessible part of the Earth’s crust so that is can be profitably extracted. The ‘sufficient concentration’ depends on the material. For example, metals like Aluminum and Iron need only a small degree of enrichment to be considered a deposit of value, compared to a precious metal like gold which needs to be present is much greater concentration to be valuable. In terms of mining ore deposits can be classified as a mineral resource if it has essential economic interest and reasonable prospects for eventual exploitation, or an ore reserve if it is an economically extractable resource; the terms depend on geological knowledge and confidence after reconnaissance. Robb, L. (2005). Introduction to ore-forming processes. Malden, MA: Blackwell Pub.

Pack ice:

from Pilford et al. (2013): Big to vast (500 m to 10 km) floes of thick (>120 cm) annual pack ice.


Pāhoehoe is a type of lava flow identified by characteristic textures. Pāhoehoe has a smooth, billowy, ropy surface like a pan of chocolate brownies.

Obtained from USGS; Photograph by J.D. Griggs on 29 July 1985

Obtained from USGS; Photograph by J.D. Griggs on 29 July 1985


Derived from Ancient Greek πέλαγος (pélagos), meaning “open sea”. The pelagic zone of the ocean begins at the low tide mark and includes the entire water column. Pelagic waters can extend over up to five horizontal zones, in descending order: the epipelagic, mesopelagic, bathypelagic, abyssopelagic, and hadopelagic.


periodically occurring, the tendency to recur in intervals.

Persistent Organic Pollutants (POPs):

POPs are essentially carbon-based compounds that are persistent in the environment (meaning they won’t break down past a certain endpoint and will just remain in the soil, water air, etc… for years or decades). Because they are persistent, they have the potential for long range transport (LRT), meaning they can often be found far away from where they were produced and initially released to remote regions like the Arctic. They also have the potential to bioaccumulate (be found at higher concentrations in organisms than in the surrounding water, air, or soil, which can potentially lead to adverse/toxic effects in humans and wildlife.
Stockholm Convention: Page on POPs
Info on POPs from the EPA


pH is a measure of the activity of protons in solution.  In a solution with low pH, the activity of the hydrogen ion exceeds the hydroxyl ion and the solution is acidic. Conversely, a solution is basic if the activity of the hydroxyl ion exceeds the activity of the hydrogen ion.



The study of life cycle events for plants and animals in reference to seasonal cycles, geographic position (such as latitude or elevation), and interannual variability. A example of a common phenological study is the timing of a spring bloom.


Population genetics:

Study of the genetic composition of biological populations, and the changes in allele frequency (the proportion of a particular allele or variant of a gene among all copies) (More here).

Primary producers:

Primary producers are all of the organisms in an ecosystem that generate their own food from organic molecules. This is most commonly done by photosynthesizing organisms like plants and cyanobacteria with help from energy from the sun. These organisms serve as the primary source of biologically available energy for all other organisms in the ecosystem.


In biology, this term refers to a stable ecosystem. When a regime shift occurs, the system is changing, often due to external forces such as extreme weather events (e.g., storms, temperature change), novel species (e.g., invasive or non-native species), or anthropogenic influence (e.g., overfishing, damning and infrastructure, pollution). These changes, or shifts as we call them, can be abrupt or occur gradually as a smooth transition to a new stable state. Regime shifts often have broad impacts on natural resources including the fishing industry.

Single nucleotide polymorphisms (SNPs):

DNA sequence variation that occurs when a single nucleotide — A, T, C or G — in the genome differs between individuals of a biological species (More here).

Spring Tide:

Greatest difference between high and low tides observed during new and full moon when the sun book and earth are approximately aligned. Tide generating forces (gravitational forces) of the sun and moon are acting in the same direction.

Stockholm Convention:

A convention that serves as a global treaty to protect human health and the environment from persistent organic pollutants (POPs). It came into force in 2004 and requires parties to take measures to reduce or eliminate the use of POPs. Currently, there are 22 chemicals listed under the convention and at least 5 more proposed for listing.


Beneath the snow. Seal pups are born in subnivean lairs where they are protected from predators and the elements.


A general term for fragments of volcanic rock and lava regardless of size that are blasted into the air by explosions, or carried upward by hot gases in eruption columns or lava fountains. Size range can be <2mm (ash) to over 1 m sized blocks.

Thermal Wind:

A general term for fragments of volcanic rock and lava regardless of size that are blasted into the air by explosions, or carried upward by hot gases in eruption columns or lava fountains. Size range can be <2mm (ash) to over 1 m sized blocks.


Turbidity Current:

A density-driven current composed of sediment and water which travels rapidly downslope through the surrounding, less dense water. Turbidity currents are often the result of submarine earthquakes, landslides or volcanic eruptions which cause a disturbance to sediment on a slope, setting it into motion. They can be particularly hazardous as evidenced by the 1929 Grand Banks earthquake, which triggered turbidity currents powerful enough to sever trans-Atlantic telegraph cables. See links for visualization:



Trophic Level:

Wind created from temperature differences in the atmosphere

Younger Dryas:

A climate event ranging from approximately 12,900 years to 11,500 years before present characterized by a return to colder conditions during a period of warming following the last glacial maximum. The name comes from the cold climate flower, the Dryas octopetala. The evidence for this climate event can be observed in temperature and ice volume proxies from ice and sediment cores from the northern hemisphere. The most supported cause of the Younger Dryas is the rapid draining of Glacial Lake Agassiz, adding significant freshwater to the Northern Atlantic Ocean, an area particularly sensitive for ocean circulation. This slowdown or shutdown of ocean circulation would have a cooling effect in the northern hemisphere.

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