Baltic Sea glossary


Phosphorus and nitrogen

Nutrients that control the growth of plants and algae. Blue-green algae are able to fixate the nitrogen they need from air, so for them, the amounts of phosphorus in the water are decisive.

Background load

Load from the natural environment, independent of the actions of people.

Blue-green algae i.e. Cyanobacteria

A group of bacteria living in aquatic habitats, able to generate the energy they need by photosynthesis, in the same way as plants do. Massive occurrences of blue-green algae, i.e. Cyanobacteria, are called blooms of blue-green algae. The masses of blue-green algae, which favour high temperatures, are usually at their worst in mid-summer.


The Baltic Marine Environment Protection Commission established by the countries surrounding the Baltic Sea: the Commission monitors the status of the Baltic Sea, and gives recommendations on actions required to save the sea.

Internal load

The release of nutrients from the seabed as a result of eutrophication. Nutrients are then used by the algae growing in the surface layers.

Non-indigenous species

A plant or animal species for which the Baltic Sea is not the original environment.

Nonpoint source load

Load originating in several small sources. Load from agriculture, for example, and wastewaters from sparsely populated areas.

Oxygen deficiency

Oxygen depletion in the water layers near the seabed and the surface of the bottom sediment.

Point load

Load originating from a clearly observable individual source. Examples include wastewaters from industrial plants and cities.

Salt pulse

A strong current of ocean water entering the Baltic Sea from the Bothnian Sea via the Danish straits. Takes place only roughly once in 10 years when the weather conditions are propitious.


Read more about the Baltic Sea:

Baltic Sea Portal