Global warming reshuffling marine plankton communities

Study featuring ensemble models of global plankton distributions suggests major restructuring of assemblages towards the end of the century with potential threat to plankton-mediated ecosystem services

GBIF-mediated data resources used : 790,103 species occurrences
Pseudo-nitzschia seriata
Pseudo-nitzschia seriata (Cleve) H.Peragallo, 1899 observed in Sausalito, CA, USA by glanglois (CC BY-NC 4.0)

Forming the basis of the ocean's food web, marine plankton are essential to a number of ecosystem services including carbon sequestration. Increasing sea temperatures may promote speciation and diversity, however, also force species to shift their ranges to more suitable climates.

In this paper, researchers built an ensemble of species distribution models for more than 800 species of phyto- and zooplankton based on occurrence records mediated by GBIF and other sources, coupled with environmental variables such as surface temperature, oxygen concentration, solar irradiance and macronutrient levels.

For the present time, the constructed models predicted strong latitudinal richness gradients with overall annual means decreasing from the equator towards the poles. Phytoplankton displayed richness peaks in tropical upwellings, whereas zooplankton peaked in the subtropics.

Projecting the models into a future climatic scenario of high greenhouse gas emissions, the researchers found an overall global increase in mean species richness by the end of the century, driven primarily by changes in ocean surface temperature. The models, however, also predicted poleward shifts of species' distributions at a velocity of 35 km/decade, leading to net increases in species diversity in temperate latitudes and decreases in the tropics.

As the ranges of species shifted, the composition of plankton communities would be restructured with novel species interactions. The authors suggested that the changes combined could weaken the biological carbon pump effect of plankton carbon sequestration with the risk of functional ecosystem collapse in particular sensitive regions.

Benedetti F, Vogt M, Elizondo UH, Righetti D, Zimmermann NE and Gruber N (2021) Major restructuring of marine plankton assemblages under global warming. Nature Communications. Springer Science and Business Media LLC 12(1). Available at: