Indicator Assessment

Phenology of marine species

Indicator Assessment
Prod-ID: IND-101-en
  Also known as: CLIM 014
Published 20 Nov 2012 Last modified 11 May 2021
7 min read
This page was archived on 03 Feb 2017 with reason: No more updates will be done
  • Temperature increases in the ocean have caused many marine organisms in European seas to appear earlier in their seasonal cycles than in the past. Some plankton species have advanced their seasonal cycle by 4–6 weeks in recent decades.
  • Projections of the phenological responses of individual species are not available, but phenological changes are expected to continue with projected further climate change.
  • Changes in the plankton phenology have important consequences for other organisms within an ecosystem and ultimately for the structure of marine food webs at all trophic levels. Potential consequences include increased vulnerability of North Sea cod stocks to over-fishing and changes in seabird populations.
This indicator is discontinued. No more assessments will be produced.

Decapoda larvae abundance and phenology in the central North Sea

Note: Left: Decapoda larvae abundance (number of individuals) in the central North Sea (1958–2009). Right: Phenology shown as average month of peak decapoda abundancein the central North Sea (1958–2009).

Data source:

Data provenance info is missing.

Past trends

The zooplankton growing season indicator shows the annual timing of peak seasonal abundance of decapoda larvae from 1958–2009 in the central North Sea (Figure 1, left). A shift towards an earlier seasonal peak is clearly visible, in particular since 1988. Since the 1990s the seasonal development of decapoda larvae has occurred 4–6 weeks earlier than the long-term average (baseline mean 1958–2009). This trend towards an earlier seasonal appearance of decapoda larvae during the 1990s is highly correlated with SSTs (Figure 1, right). Even though decapoda larvae are not routinely identified to species level, a recent study has shown that these phenological shifts are a response at the species level, and not simply different seasonal timings by different species [i].


Projections of the phenological responses of individual species under climate change have not yet been made, but the empirical evidence suggests that phenological changes will continue as climate warming continues. It is currently uncertain as to whether genetic adaptations within species populations can cope with these changes, at least partly, or whether the pace of climate change is too fast for genetic adaptations to take place. This uncertainty is further compounded by the difference in phenological responses between species and functional groups. If current patterns and rates of phenological change are indicative of future trends, future climate warming may exacerbate trophic mismatching. This could further disrupt the functioning, persistence and resilience of many ecosystems, potentially having a major impact on ecosystem services.

[i] John A. Lindley and Richard R. Kirby, „Climate-induced changes in the North Sea Decapoda over the last 60 years“, Climate Research 42, Nr. 3 (September 16, 2010): 257–264.

Supporting information

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.



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

Data sources

Other info

DPSIR: Impact
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)
Indicator codes
  • CLIM 014
Frequency of updates
This indicator is discontinued. No more assessments will be produced.
EEA Contact Info


Geographic coverage

Temporal coverage




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