Indicator: Ecological status of transitional and coastal waters

A diagram shows the distribution of the ecological status/ecological potential of transitional and coastal waters for the North Sea and the Baltic Sea for the years 2010, 2015 and 2021. The target for 2027 is shown (100 % good or very good).Click to enlarge
Percentage of water bodies in transitional and coastal waters in at least good status
Source: Voß et al. Figure as PDF

Table of Contents


At a glance

  • In 2021 no water body of transitional or coastal waters in the North and Baltic Seas achieved good or very good status.
  • According to the European Water Framework Directive, by 2015 and with a deadline extension to 2027 all waters should have achieved at least a good ecological status.
  • The time must now be used to reach the ambitious targets by 2027 at the latest.
  • This will require considerable additional efforts.

Environmental importance

The high input of nutrients such as nitrogen and phosphorous into the North and Baltic Seas leads to a large growth of algae. A high density of algae causes a shortage of light at greater depths. Plants which require light are suppressed. If the algae and other plants die, they are decomposed by microorganisms. This process uses up oxygen and the oxygen concentration of the water declines. This can cause animals to suffocate. Large areas of the Baltic Sea now have low oxygen levels or contain no oxygen.

The Baltic Sea and North Sea are quite different in terms of their nutrient and oxygen concentrations. The North Sea constantly exchanges water with the Atlantic and Arctic Oceans and is generally more turbulent. The Baltic Sea, on the other hand, is only connected to the North Sea and the connections are very narrow. It therefore has the character of an inland sea and reacts more sensitively to excessive nutrient inputs.


Assessing the development

In 2021 no water body of the coastal and transitional waters of the German parts of North and Baltic Seas achieved good or very good ecological status. The target set by the European Water Framework Directive (WFD, EU Directive 2000/60/EC) i.e. that all waters should be in at least a good environmental status by 2015, was therefore missed by a wide margin. As this goal was clearly missed, the subsequent management cycle under the WFD now needs to be used to reach the ambitious targets by the deadline extension to 2027 at the latest.

The reason for missing the targets is primarily the excessive input of nutrients into coastal and transitional waters (eutrophication). These mainly come from agriculture, sewage treatment plants and shipping. The nutrients enter the sea via rivers or the atmosphere (cf. ‘Eutrophication of the North Sea and Baltic Sea’ and ‘River eutrophication by phosphorous’ indicators). The measures taken so far are not (yet) taking effect to an adequate degree. Efforts must be significantly increased in order to reduce nutrient inputs to a level which allows a good status to be achieved.

Compared to 2015 there has been an increase in the proportion of bad and poor areas. This can be explained mainly from the much improved availability of data and modified threshold values. In reality there has been almost no deterioration.



Determining the ecological status of coastal and transitional waters basically requires analysis of the species composition of selected plant and animal communities which function as indicators: to what degree do they correspond to the typical composition of the particular habitat? Five status classes are defined, depending on the degree of divergence from the natural status, from ‘very good’ to ‘bad’. A detailed description of the evaluation of water bodies has been published by Voß et al. (2010).

More detailed information: 'Ökologischer Zustand der Küstengewässer der Nordsee' and 'Ökologischer Zustand der Küstengewässer der Ostsee' (in German only).