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Albers Equal Area Projection

A conic projection which allows for the accurate measurement of area on a map.


Amphidromic Point

Point within tidal system where tidal range is almost zero.



Man made activity / cause.


Background Assessment Concentration

A concentration sufficiently close to the measured background concentration (the measured concentration of a contaminant at a ‘pristine’ or ‘remote’ site) to be considered of no concern.


Background Response Range

Biological response to a test in organisms from an uncontaminated environment.



Contour of the shape of the sea bed to give depth of water.



Benthic zone is the ecological region at the sea bed including the rock / sediment surface and some sub-surface layers. Organisms living here are called benthos.


Biogeochemical processes

The chemical, physical, geological, and biological processes and reactions that govern the composition of the natural environment (including the biosphere, the hydrosphere, the pedosphere, the atmosphere, and the lithosphere). In the sea, biogeochemical processes are responsible for the recycling of nutrients between plants, animals and sediments, and also for processes that transform pollutants into more or less biologically available forms.


Brominated Flame Retardants

Compounds containing bromine that are added to many products (electrical equipment, electronics, textiles) to reduce the risk of fire.


Byssus threads

Silky filaments by which some bivalve molluscs attach themselves to hard surfaces.


Carbon Capture and Storage

Collecting CO2 from industrial processes and storing it in geological formations underground / under sea.



Includes the marine mammals commonly known as whales, dolphins and porpoises.


Close to Background Response Range

The biological response to contaminants which is close to the response of organisms in an uncontaminated environment.



Includes herrings, shads and sardines, typically plankton feeders and forage fish.



The meeting of two or more bodies of water.


Conservation Credits

Credits (in the form of days at sea) made available by Scottish Government to fishermen who adopt conservation measures.


Deep Waters

Waters in excess of 2,000m depth.


Effects Range

The range of contaminant concentrations used to predict adverse biological effects on organisms.


Elevated Response Range

Elevated biological response in the test organism due to the presence of contaminants.


Endocrine disruptors

Substances that interfere with the hormone system.


Environmental Assessment Criteria (EAC)

The contaminant concentration in the environment below which no chronic effects are expected to occur in marine species.



Aquatic animals that live on the surface of other animals or plants.


Fishing Mortality Rate

The number of fish being removed from the stock year on year minus an estimate of the amount of natural (i.e. non-fishing-related) mortality.



Shallow sea lochs created when rising sea levels flooded low-lying coastal land after the last Ice Age, e.g. Loch nam Madadh (Loch Maddy).



Generally long, narrow sea lochs with steep sides or cliffs, created when rising sea levels flooded valleys carved by Ice Age activity.



The fishing mortality rate at which the stock may continue to be exploited without affecting its reproductive potential (assuming environmental factors remain unchanged.



System of rotating ocean currents.


High Effect Response Range

Indicates the level at which a hazardous substance has caused an unintended or unacceptable level of biological response in the test organism.


A condition in which male sexual characteristics are superimposed on female gastropod molluscs.



Fertile low-lying grassy coastal areas, in particular in the Outer Hebrides.


Maximum Sustainable Yield

The maximum catch that can be taken from a stock without affecting its reproductive potential (assuming environmental factors remain unchanged).



Changes in the shape of, for example, beaches or sea bed; or differences between species.



Phytoplankton that are between 2 µm and 20 µm in diameter.


Nitrate Vulnerable Zone

Area designated under Nitrates Directive due to sensitivity to nitrates in the water.



Chemical elements or compounds that are essential for animal and plant growth.  In the sea, the term normally refers to compounds of nitrogen, phosphorus (and silicon) that are required by phytoplankton and other plants for growth.


Oxidative Stress

Change in the ability of organisms to detoxify reactive oxygen species produced in cells.



Microscopic, single celled organisms which are free floating in the water column.  Most phytoplankton contains the pigment chlorophyll which is used in the process of photosynthesis.  Phytoplankton are also referred to as ‘microalgae’.



Phytoplankton that are between 0.2 µm and 2 µm in diameter.


Planar Organic Contaminants


Organic contaminants where the atoms are in the same plane.


Depressions in the sea bed caused by fluids (gas and liquids) erupting and through the seabed sediments.



The process used to reduce a three-dimensional geographical area (on a globe) to a flat map.


Representative Monitoring Point

The monitoring point considered to be representative of several locations.


Spawning Stock Biomass

Total weight of mature fish (i.e. fish of reproductive age) in a particular stock.



Deposition landforms found at the coast, connected to the land at one end and extending into the sea, for example, at Culbin Sands and Whiteness Head.



The part of the global ocean circulation driver by temperature and salinity differences (density gradients).



Cloudiness or haziness of sea water caused by individual particles or suspended solids. Reduces the depth to which light can penetrate.



The portion of plankton that belong to animal kingdom.  Consists mainly of small crustaceans (e.g. copepods or decapod larvae), fish larvae and eggs.