Indicator Specification

Distribution of marine species

Indicator Specification
  Indicator codes: CLIM 015
Published 20 Nov 2012 Last modified 04 Dec 2019
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This page was archived on 20 Dec 2016 with reason: Other (New version data-and-maps/indicators/northward-movement-of-marine-species-2 was published)
Calanus ratio in the North Sea Annual mean number of Calanus per sample

Assessment versions

Published (reviewed and quality assured)
  • No published assessments


Justification for indicator selection

Changes in the distribution of organisms are one of the key indicators of marine climate change impacts. Distribution maps from the North-east Atlantic are used as one part of this indicator to demonstrate large-scale changes at the decadal scale. The second part of this indicator describes the ratio between a warm-water species (Calanus helgolandicus) and a cold-water species (Calanus finmarchicus) in the North Sea on an annual basis. In the eastern Mediterranean Sea, the introduction of warm and tropical alien species from the Red Sea has been exacerbated by observed warming, leading to a 150 % increase in the annual mean rate of species entry after 1998.

Changes in marine plankton can trigger further effects on marine and terrestrial ecosystems. For example, increases in the surface temperature of the North Sea in recent decades have triggered establishment of warm-water swimming crabs, which in turn allowed establishment of colonies of lesser black-backed gulls in Belgium and northern France, with expected follow-on impacts on terrestrial ecosystems through their fertilisation of terrestrial soils.

Scientific references

Indicator definition

  • Calanus ratio in the North Sea
  • Annual mean number of Calanus per sample


  • Ratio [dimensionless]
  • Number of Calanus [dimensionless]

Policy context and targets

Context description

In April 2013 the European Commission presented the EU Adaptation Strategy Package ( This package consists of the EU Strategy on adaptation to climate change /* COM/2013/0216 final */ and a number of supporting documents. One of the objectives of the EU Adaptation Strategy is Better informed decision-making, which should occur through Bridging the knowledge gap and Further developing Climate-ADAPT as the ‘one-stop shop’ for adaptation information in Europe. Further objectives include Promoting action by Member States and Climate-proofing EU action: promoting adaptation in key vulnerable sectors. Many EU Member States have already taken action, such as by adopting national adaptation strategies, and several have also prepared action plans on climate change adaptation.

The European Commission and the European Environment Agency have developed the European Climate Adaptation Platform (Climate-ADAPT, to share knowledge on observed and projected climate change and its impacts on environmental and social systems and on human health; on relevant research; on EU, national and subnational adaptation strategies and plans; and on adaptation case studies.


No targets have been specified.

Related policy documents

  • Climate-ADAPT: Adaptation in EU policy sectors
    Overview of EU sector policies in which mainstreaming of adaptation to climate change is ongoing or explored
  • Climate-ADAPT: Country profiles
    Overview of activities of EEA member countries in preparing, developing and implementing adaptation strategies
  • DG CLIMA: Adaptation to climate change
    Adaptation means anticipating the adverse effects of climate change and taking appropriate action to prevent or minimise the damage they can cause, or taking advantage of opportunities that may arise. It has been shown that well planned, early adaptation action saves money and lives in the future. This web portal provides information on all adaptation activities of the European Commission.
  • EU Adaptation Strategy Package
    In April 2013, the European Commission adopted an EU strategy on adaptation to climate change, which has been welcomed by the EU Member States. The strategy aims to make Europe more climate-resilient. By taking a coherent approach and providing for improved coordination, it enhances the preparedness and capacity of all governance levels to respond to the impacts of climate change.

Key policy question

How is climate change affecting the regional distribution of marine organisms in European seas?



Methodology for indicator calculation

Data from the Sir Alister Hardy Foundation for Ocean Science (SAHFOS) on Calanus abundance in the central North Sea 1958–2009 is used for the indicator. The Continuous Plankton Recorder (CPR) survey is the longest running, large-scale marine biological survey in the world. The CPR is a near-surface (10 m) plankton sampler voluntarily towed each month behind merchant ships on their normal routes of passage. Methods of analysis for, 400 phyto and zooplankton taxa have remained almost unchanged since 1958.

Methodology for gap filling

Not applicable

Methodology references


Data specifications

EEA data references

  • No datasets have been specified here.

External data references

Data sources in latest figures



Methodology uncertainty

Not applicable

Data sets uncertainty

In general, changes related to the physical and chemical marine environment are better documented than biological changes because links between cause and effect are better understood and often time series of observations are longer. The longest available records of plankton are from the Continuous Plankton Recorder (CPR) are some 60 years long. It is a sampler that is towed behind many different merchant vessels, along fixed shipping routes. Sampling was started in the North Sea in the 1950s and today a network covering the entire north Atlantic has been established. No other plankton time series of equivalent length and geographical coverage exist for the European regional seas, although many new initiatives investigating species distributions and their changes in Europe’s seas are now emerging.

Further information on uncertainties is provided in Section 1.7 of the EEA report on Climate change, impacts, and vulnerability in Europe 2012 (

Rationale uncertainty

No uncertainty has been specified

Further work

Short term work

Work specified here requires to be completed within 1 year from now.

Long term work

Work specified here will require more than 1 year (from now) to be completed.

General metadata

Responsibility and ownership

EEA Contact Info

Trine Christiansen


European Environment Agency (EEA)


Indicator code
CLIM 015
Version id: 2

Frequency of updates

Updates are scheduled every 4 years


DPSIR: Impact
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)


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