Marine Research Findings of the VECTORS Project

This website provides access to the research results of the VECTORS project, which can be used to support marine management decisions, policies and governance as well as future research and investment. VECTORS was a large scale project that brought together more than 200 expert researchers from 16 different countries. It examined the significant changes taking place in European seas, their causes, and the impacts they will have on society.

Sensitivity of Calanus spp. copepods to environmental changes in the North Sea

The two copepods Calanus finmarchicus and C. helgolandicus are considered key species in the North Sea ecosystem because they serve as prey for commercially important fish species. However, long-term changes in the ecosystem have been linked to global warming resulting in a northward extension of C. helgolandicus and a decline of C. finmarchicus. However, the understanding of the underlying mechanisms and their interactions is still limited. To broaden this knowledge, the present study embeds stage-structured models of the two Calanus species in a 3D coupled hydrodynamic-biogeochemical model to investigate the sensitivity of these species distributions to changes in sea water temperatures, overwintering and oceanic inflow in the North Sea.


Changes in temperatures, oceanic inflow and overwintering will cause changes in the vertical, spatial and seasonal distributions of the two important copepod Calanus species in the North Sea.

Model results show that i) ± 2°C changes from the current level mainly influence the vertical distribution (Fig. 1) and seasonal patterns (Fig. 2), but not the relative occurrence of the two species, ii) changes due to oceanic inflow mainly appeared in the northern and southern part of the North Sea connected to the NE Atlantic and not in the central part (Fig. 3G+H) and iii) the abundance of Calanus species were very sensitive to the degree of overwintering within the North Sea (Fig. 3E+F) because it allows them to utilise the spring bloom more efficiently and independently of the timing and amount of oceanic inflow.

The +2°C scenario suggest that in a warmer future, C. finmarchicus is likely to decline and C. helgolandicus abundance will probably continue to increase in some areas.

Vertically, both species are predicted for descent to deeper and cooler waters during summer in order to avoid the warmer surface layer with C. finmarchicus located deeper than C. helgolandicus in the water column (Figure 1).

The first seasonal increase in abundances of C. finmarchicus and C. helgolandicus were accelerated with app. 2 weeks at higher temperatures (+2T) and similarly delayed at lower temperatures (-2T) in comparison with 2005 (Fig. 2). These potential future temporal-spatial patterns may change the match/mismatch with predators and hence the production of planktivorous fish species. The modelled distributions of Calanus can potentially serve as prey fields in other models describing fish productivity and bottom-up effects from climate variability.

Relevance for Policy:
  • Marine Strategy Framework Directive
Data availability:

Data used: Model data created

Where it is held: AU/NERI

Contact: Marie Maar

Availability: The data can be obtained by emailing the contact person.
See publication:

Lead Author:

Marie Maar
Aarhus Universitet (NERI)
Date of research: October 2012

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Impact of environmental changes on North Sea herring

Response of plaice and sole to climate change 

Spatial overlap and recruitment success of cod 

The drivers of a common sole population 

Zooplankton mortality and fish consumptions 

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This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 266445
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