Example

• Sentinel Fisheries

Adsorption
The retention of gases, dissolved chemicals, or ions on the surface of solid particles. These particles may occur in water column (see: suspended particulate matter), sediments or biota.

Age class
All fish in a stock that are the same age, such as all three-years olds.

Anoxic (bottom waters, sediments)
Waters that are near the sea floor and bottom sediments whose oxygen content has been depleted by high levels of decomposition and biological activity.
 

Example:

• 3D image (Estuary)
   
• 3D image (Fjord)

Benthic
The sea bottom environment, regardless of depth, and the organisms that inhabit that environment (see: Benthos). The benthic zone, along with the pelagic zone, is one of the two major divisions of marine ecosystems.

Benthos
Plant and animal organisms that live on or in sea bottom sediments. Benthos can include benthic fish as well as true bottom dwellers such as shellfish and sea worms.

Biological cycling
The continuous transfer of energy and material between different organisms. For example, plankton are consumed as food by a prey species such as capelin, which in turn become food for higher-level predator species such as cod. The cod in turn becomes food for higher-order predators or for scavengers or detritivores (that consume detritus) when it dies.

Examples:

• Carbon cycle
   
• Ecosystems Modelling

Biological production
The production of organic matter by organisms in a specific area.

Biomass
The total mass of a species (plant or animal) or a group of species within a defined area, at a given time, expressed per unit area or volume.
In fisheries, the area is often defined as the region inhabited by a particular fish stock, and the biomass is measured in metric tonnes per stock.
The spawning biomass is the sexually mature portion of a fish population that is ready to reproduce. In some species (e.g., haddock, cod), spawning adults congregate into a distinct group referred to a spawning aggregate.

Example:

• Sentinel Fisheries

Biota
All of the living organisms (animals and plants) found in a given area.

Bloom (phytoplankton)
The proliferation, at a given site, of a species of phytoplankton due to the rapid change of certain natural factors, such as sunlight, water temperature, or nutrient salt concentrations.

Examples:

• Phytoplankton bloom

• Images

Buoy (oceanog., meteo)
An oceanographic / meteorological buoy (moored or drifting) is a floating device designed for recording parameters such as water and air temperatures, barometric pressure, wind direction and speed, seawater salinity, etc.

Example:

• On-Line Scientific Buoys

Example:

• 3D image (Trough)
   
• 3D image (Gulf)

Example:

• Carbon cycle

Classification
The systematic grouping and naming of plant and animal organisms according to physical characteristics. (Also known as taxonomy). The smallest group which is regularly distinguished is the species. Species are grouped into genera, genera into families, families into orders, orders into classes, classes into phyla (animals) or divisions (plants), and phyla or divisions into kingdoms, the highest taxonomic ranking.

Example:

• Ecosystems Modelling

Coastal zone
Zone of interaction between the land and the marine environment. The land and sea boundaries of the coastal zone vary widely from one location to another. On land, it encompasses the sector containing the majority of shoreline uses that have a direct influence on coastal habitats and resources (e.g., fisheries resources). Away from shore, the coastal zone should be limited to the area where the majority of uses occur, such as inshore fishing, coastal navigation and aquaculture.

Community
An assemblage of organisms characterized by a distinctive combination of species occupying a common environment and interacting with one another.

Coriolis force
The tendency for moving objects to turn counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere due to the Earth's rotation. Local phenomena can modify this tendency.
 

Examples:

• Temperature and salinity profiles
   
• Front (aerial view)

Detritus
Unconsolidated sediments composed of both inorganic and dead and decaying organic material. Detritus is the basic food for animals known as detritivores, which break down the material and re-introduce it into the food web.

Example:

• Carbon cycle

Dinoflagellate
Microscopic alga characterised by the presence of two whiplike flagella.

Examples:

• Phytoplankton monitoring
   
• Dinoflagellate (picture)

Downstream
The part of a water body from a given point toward the river's mouth, usually where the river empties into the sea.

Drainage basin
The land area over which surface water and groundwater is carried by the natural slope of the land to streams, rivers, bays, gulfs, seas, and oceans. Streams have the smallest drainage basins and oceans have the largest.
 

Example:

• Ecosystem Modelling

Effluent
Generally applies to any run-off from a pollution source.

Entrainment
The waters contained by a large body of water often have different physical properties. The physical forces can be different from subregion to subregion. Entrainment refers to the occasions when a large amount of water having particular properties (e.g., temperature and salinity) is trapped or carried within an even larger mass of water that has different properties. The entrained mass can be carried large distances, both vertically and horizontally.

Estuary
The downstream area of a coastal river that is affected by the tides of the ocean into which the river flows and where fresh and salt waters meet. (e.g., the St. Lawrence estuary). Estuarine flow refers to the general tendency for the surface waters to be fresh (how deep the surface is depends on the estuary) and flowing out of the estuary while the bottom flow of water is saline and into the estuary. It is because the saline water is denser than the fresh water that saline water is found near the bottom of the estuary. (see: salinity).

Example:

• Density gradient

Eutrophic
Waters that are abundant in nutrients and have high rates of productivity frequently result in oxygen depletion below the surface layer of a water body.
 

Fish

According to the Fisheries Act, that includes fish, shellfish, crustaceans, marine animals and any parts of fish, shellfish, crustaceans or marine animals, and the eggs, sperm, spawn, larvae, spat and juvenile stages of fish, shellfish, crustaceans and marine animals (see: Habitat; Spawning ground; Recruitment; Schooling behaviour; Stock).
Groundfish such as flounder, cod, plaice, halibut, redfish and stingrays, inhabit and derive their food from the sea bottom. (Demersal fish or benthic fish are sometimes used as synonyms). By opposition, pelagic fish, such as capelin and herring, live in the water column.

Example:

• Sentinel Fisheries

Fisheries resources
According to the Policy for the Management of Fish Habitat, fish, stocks or populations that sustain commercial, recreational, or native fishing activities of benefit to Canadian.
Fisheries management is the application of regulation such as catch quotas and licensing to limit a fishery to meet specific objectives. Fisheries management objectives are often defined in terms of government policy.

Flora
The plant population of a specific environment.

Flux
Transfer of a substance between two environments.

Example:

• Carbon cycle

Food web
The interrelationships between the different food chains found in particular area. Whereas food chains are simple linear relationships, food webs are more complex and encompass both predator/prey and predator/predator relationships between trophic levels.

Example:

• Plankton food chains

Example:

• Oceanogaphic data management system

Examples:

• Density gradient

Grain-size distributions (particles, sediments)
The percentages (by weight or count) of mineral particles of different sizes in particular sediments. These particles and their sizes include clay (less than 2 µm), silt (2-64 µm), sand (64 µm-2 mm), granules (2-4 mm), gravel (4 mm-6 cm), cobbles (6-25 cm) and boulders (greater than 25 cm).

Gyre
A “circular” movement of water formed by wind activity, upwellings or currents, especially when the latter pass obstructions or when two adjacent currents run counter to each other (e.g., the Anticosti gyre in the St. Lawrence estuary). They play an important role in the transport of dissolved substances, heat, and momentum (see: Coriolis force).

Heat budget
The balance or imbalance between the amount of heat received by an area from solar radiations and the amount that an area losses through processes such as evaporation, re-radiation, and reflection. The heat budget for a given area varies daily and seasonally. On an annual basis, higher latitudes such as those of Atlantic Canada locally lose heat but it is replaced by heat originating from equatorial latitudes via winds and ocean currents.

Hydrodynamic
Having to do with the movement of liquids or with fluid mechanics; study of the circulation of liquids and the forces exerted by liquids. (see: Coriolis force; Gyre)

Example:

• Tidal propagation

Intertidal zone
The marginal area between the highest water mark and the lowest water mark. It is periodically flooded by tides.
 

Example:

• Phytoplankton monitoring

Example:

• Carbon cycle

Organism
A living individual animal or plant.
 

Photosynthesis
Production of new organic material (carbohydrates) by plant and algae using carbon dioxide (as carbon source) and water. Plants and algae that contain chlorophyll (pigment) have the ability to fix carbon dioxide, using sunlight as a source of energy.

Example:

• Sentinel Fisheries

Phytoplankton
All plankton organisms belonging to the Plant kingdom.

Example:

• Phytoplankton monitoring
   
• Plankton food chains

Plankton
All animal (zooplankton) and plant (phytoplankton) organisms, generally of very small size, which live suspended in the water column. They drift in the sea and are the basic food source for many marine mammals and fish. Plankton include a vast group of minute organisms.

Example:

• Plankton food chains

Population
A closely associated group of individuals of the same species that occupy a common area, such as beluga of the St. Lawrence estuary, cod on the Grand Banks, etc.
Population dynamics: study of changes in population structure.

Primary production
The amount of new organic matter produced from inorganic material by organisms using photosynthesis.

Example:

• Carbon cycle

Productivity
The rate at which a population, species or ecosystem produces new individuals over a specific time period.

Protozoan
Unicellular organism, generally microscopic.

Example:

• Plankton food chains

Resuspension (contaminants, sediments)
The transfer of dissolved contaminants and contaminated particles from sediments to the overlaying water through chemical processes (oxidation and reduction reactions). Resuspension may be enhanced by processes such as physical mixing or bioturbation. (see: Suspended particulate matter).

Examples:

• On-Line Scientific Buoys
   
• Shipboard Thermosalinographs

Schooling behaviour (fish)
The gathering together of fish species into large dense groups for feeding, protection and reproduction. Even if the total population of a schooling species decreases due to fishing, natural predation or environmental change, the density of fish within a given school generally remains substantially unchanged. It is thus possible to harvest large quantities of a fish species whose total overall population may be declining. (see: Stock; Recruitment).

Sediment
Marine sediment is all of the natural particles (muds, clays, shells and dead organic matter - the remains of living organisms - ) settled into the water column and transported on the sea bottom. A sediment is characterized by the nature and relative proportions of the chemical and mineral components (see: Grain-size distribution).

Example:

• Carbon cycle

Seagrass bed
Large underwater grassland or aquatic environment dominated by floating vegetation, algal vegetation or submerged vegetation.

Simulation
Method of representing physical phenomena, using a computer or a model.

Example:

• Tidal propagation

Slack tide
Time during the tidal cycle when the sea level is stabilized; also called “slack water”.

Example:

• Tides predictions

Spawning ground
Place where the female fish lays its eggs and the male fertilizes them.

Species
A taxonomic grouping of plants or animals of common ancestry that closely resemble each other and can produce fertile offspring.

Stock (fishable stock)
The part of a stock that is available to be fished. The fish must be big enough to be caught and must live in places where fishermen work to be part of the “fishable stock”.

Example:

• Sentinel Fisheries

Stratification (water masses)
The separation of a body of water into vertical layer (strata) that have differing densities due to variations in temperature or salinity. Stratified marine systems of this type are generally characterized by warmer, less dense waters on top and colder, denser waters on the bottom.

Examples:

• Temperature and salinity profiles
   
• Density gradient

Subtidal zone
The area of sea bottom between the low tide level and the continental shelf; (also known as the sub-littoral zone).

Suspended particulate matter
The relatively fine particles (primarily clay, silt, small organic and inorganic debris, plankton and microscopic organisms) that drift with water currents and only slowly settle out to form the sediments that underlie rivers, bays, gulfs and oceans.

Example:

• Carbon cycle

Sustainable yield
The portion of a fish population that can be harvested continuously without impairing its ability to renew itself through reproduction and recruitment. The sustainable yield also can be defined as the annual increase in biomass (growth and recruitment) within a stable population.

Tidal front
A tidal front is a density front that occurs between nearshore and offshore waters and is produced when the density of the shallower nearshore water is altered through mixing by tides.

Examples:

• Density gradient
   
• Front (aerial view)

Tide
Periodic rise and fall of the sea level due to the gravitational attraction of the moon and sun on water masses. (see: Internal tides)
Semi-diurnal tide: the most frequent tidal cycle, with two high tides and two low tides in the same day (e.g., tides in the St. Lawrence Estuary).

Example:

• Tide predictions

Transect
Narrow strip or line (real or virtual) in a given environment, used for analysis, description and mapping.

Trophic level
A portion of the food chain in which all organisms obtain food and energy in essentially the same manner (see: Food web).

Example:

• Ecosystem Modelling

Turbidity
A decrease in water clarity, thus preventing penetration of light. It results from the presence in water column of suspended particulate matter.

Upstream
Section of a water body between a given point and the source.

Upwelling
The rising to the sea surface of cold, dense subsurface water. Upwelling can occur when two currents diverge or where surface water is displaced by physical forcing. Upwelled seawater, in addition to being cooler, is also often rich in nutrients, so that regions of upwelling are generally also regions of rich biological activity. Tidal upwelling occurs when tide-induced currents flow away from the coastline, displacing surface waters.

Example:

• Temperature and salinity profiles

Example:

• Temperature and salinity profiles

Wavelength
Distance between two successive crests of a wave.
 

Example:

• Plankton food chains