Reinterpreting two regime shifts in North Sea plankton communities through the lens of functional traits

Type Article
Date 2023-06
Language English
Author(s) Djeghri NicolasORCID1, Boyé AurélienORCID2, Ostle Clare1, Hélaouët Pierre1
Affiliation(s) 1 : Continuous Plankton Recorder Survey The Marine Biological Association Plymouth, UK
2 : Laboratory of Coastal Benthic Ecology Ifremer, Centre de Bretagne, DYNECO Plouzané ,France
Source Global Ecology and Biogeography (1466-822X) (Wiley), 2023-06 , Vol. 32 , N. 6 , P. 962-975
DOI 10.1111/geb.13659
Keyword(s) Continuous Plankton Recorder, ecosystem functioning, functional traits, North Sea, plankton, regime shift


The so-called regime shifts in North Sea plankton communities provide an important historical case study to understand marine regime shifts. Previous studies characterized regime shifts using a variety of community metrics (e.g., indicator species abundances, taxonomic composition and chlorophyll biomass) but left the functional traits of plankton unassessed. Here, we explicitly re-assess the historically recognized North Sea regime shifts through the lens of plankton functional traits to gain a better understanding of these events.


The North Sea (NW European shelf).

Time period

1958–2018, focusing on the 1980s and 1996–2003 regime shifts.

Major taxa studied

Marine phyto- and zooplankton.


We compute trait spaces for both phyto- and zooplankton of the North Sea using traits from the literature and a Gower's distance-based method. Using abundance data from the Continuous Plankton Recorder Survey, we then compute monthly time series of the centroids of the communities, an indicator of functional composition. We then use principal component analysis on the centroids to assess the main temporal changes in plankton functional composition associated with the 1980s and 1996–2003 regime shifts.


Little change in plankton functional composition was associated with the 1980s regime shift. In contrast, the functional composition of plankton communities changed markedly after the 1996–2003 regime shift, with an increase in the summer relative abundance of non-motile autotrophs (i.e., diatoms) and the spring relative abundance of meroplankton.

Main conclusions

The North Sea regime shifts were not associated systematically with changes in functional composition, calling into question the definition of regime shifts and illustrating the importance of taking different metrics into account to interpret ecological events accurately. Taking into account functional composition, we interpret the 1980s so-called regime shift as a latitudinal shift in communities that was insufficient to impact functional composition and the 1996–2003 so-called regime shift as a period of change in bentho-pelagic coupling.

Full Text
File Pages Size Access
Publisher's official version 14 10 MB Open access
Appendix S1 31 KB Open access
Appendix S2 288 KB Open access
Appendix S3 280 KB Open access
Top of the page