Phytoplankton life strategies, phenological shifts and climate change in the North Atlantic Ocean from 1850‐2100

Supporting data for the article entitled 'Phytoplankton life strategies, phenological shifts and climate change in the North Atlantic Ocean from 1850-2100'.

Article abstract: Significant phenological shifts induced by climate change are projected within the phytoplankton community. However, projections from current Earth System Models (ESMs) understandably rely on simplified community responses that do not consider evolutionary strategies manifested as various phenotypes and trait groups. Here, we use a species-based modelling approach, combined with large-scale plankton observations, to investigate past, contemporary and future phenological shifts in diatoms (grouped by their morphological traits) and dinoflagellates in three key areas of the North Atlantic Ocean (North Sea, North-East Atlantic and Labrador Sea) from 1850 to 2100. Our study reveals that the three phytoplanktonic groups exhibit coherent and different shifts in phenology and abundance throughout the North Atlantic Ocean. The seasonal duration of large flattened (i.e., oblate) diatoms is predicted to shrink and their abundance to decline, whereas the phenology of slow-sinking elongated (i.e., prolate) diatoms and of dinoflagellates is expected to expand and their abundance to rise, which may alter carbon export in this important sink region. The increase in prolates and dinoflagellates, two groups currently not considered in ESMs, may alleviate the negative influence of global climate change on oblates, which are responsible of massive peaks of biomass and carbon export in spring. We suggest that including prolates and dinoflagellates in models may improve our understanding of the influence of global climate change on the biological carbon cycle in the oceans.

The data provided here are the observed and modelled abundances (oblate and prolate diatoms and dinoflagellates), the observed and modelled environmental data (compiled data for sea surface temperature, Surface Downwelling Shortwave Radiation and disolved nitrates concentrations) in the North Sea, the North-East Atlantic and the Labrador Sea, and the phenological indices for the three different phytoplanktonic groups (i.e. oblate and prolate diatoms and dinoflagellates) and the three warming scenarios (the low, the medium and the high warming scenarios; SSP1-1.2.6 SSP2-4.5 and 5-8.5 respectively). The phenological indices are the maximum abundance, the day where the maximum abundance is reached, the day where the seasonal reproductive period is initiated and the day where it is terminated, the seasonal duration and the mean annual abundance.