Indicator Specification

Phenology of marine species

Indicator Specification
  Indicator codes: CLIM 014
Published 20 Nov 2012 Last modified 18 Apr 2017
6 min read
This page was archived on 03 Feb 2017 with reason: No more updates will be done
Decapoda larvae abundance and phenology in the central North Sea
This indicator is discontinued. No more assessments will be produced.

Assessment versions

Published (reviewed and quality assured)
  • No published assessments


Justification for indicator selection

Phenology is the study of annually recurring life-cycle events of species, such as the timing of migrations and flowering of plants. In the marine environment, phenology indicators include the timing of the spring phytoplankton bloom and the peak in abundance of other marine organisms. Change in phenology is one of the key indicators of the impacts of climate change on biological populations. Because marine species have different sensitivities to changes in temperature, these changes may lead to large shifts in the marine food web that can ultimately affect the food available to fish, birds or marine mammals. Differing responses have been seen across various levels of the food web.

Changes in the phenology of different plankton species are seen as a factor contributing to the decline in North Sea cod stocks, which was caused initially by over-fishing, and they have probably affected other fish populations (such as sand eels) that are an essential food source for seabirds.

In the North Sea, work on pelagic phenology has shown that plankton communities, including fish larvae, are very sensitive to regional climate warming. Responses to warming vary between trophic levels and functional groups, which may create a so-called ‘trophic mismatch’ between one species and their food source. The sexual maturation of decapoda larvae has been found to be particularly sensitive to water temperature and is therefore regarded as representative of phenological changes in the shelf-sea environments. Other taxa that also have their seasonal development closely triggered by temperature changes are also highly sensitive (e.g. echinoderm larvae, dinoflagellates, copepods).

Scientific references

  • No rationale references available

Indicator definition

  • Decapoda larvae abundance and phenology in the central North Sea


  • Mean number of decapods per sample
  • Month of peak abundance

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.


Methodology for indicator calculation

Data from the Sir Alister Hardy Foundation for Ocean Science (SAHFOS) on Decapoda larvae 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

No methodology references available.


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 014
Version id: 2

Frequency of updates

This indicator is discontinued. No more assessments will be produced.


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



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