Faster Atlantic currents drive poleward expansion of temperate phytoplankton in the Arctic Ocean

Abstract

The Arctic marine biome, shrinking with increasing temperature and receding sea-ice cover, is tightly connected to lower latitudes through the North Atlantic. By flowing northward through the European Arctic Corridor (the main Arctic gateway where 80% of in-and outflow takes place), the North Atlantic Waters transport most of the ocean heat, but also nutrients and planktonic organisms toward the Arctic Ocean. Using satellite-derived altimetry observations, we reveal an increase, up to two-fold, in North Atlantic current surface velocities over the last 24 years. More importantly, we show evidence that the North Atlantic current and its variability shape the spatial distribution of the coccolithophore Emiliania huxleyi (Ehux), a tracer for temperate ecosystems. We further demonstrate that bio-advection, rather than water temperature as previously assumed, is a major mechanism responsible for the recent poleward intrusions of southern species like Ehux. Our findings confirm the biological and physical "Atlantification" of the Arctic Ocean with potential alterations of the Arctic marine food web and biogeochemical cycles.

Shifts in Phytoplankton Composition and Stepwise Climate Change During the Middle Miocene

“…floridanus and Sphenolithus (with high thermal optima) and demonstrating the high adaptability of the Reticulofenestra lineage to the new "baseline" conditions of the middle Miocene "icehouse world." We speculate that a regression to a warmer state of the oceans may not negatively impact highly adaptable coccolithophore taxa, such as E. huxleyi, whose poleward expansion is already evident (Oziel et al, 2020;Rivero-Calle et al, 2015;Winter et al, 2014).…”

Understanding Regional and Seasonal Variability Is Key to Gaining a Pan-Arctic Perspective on Arctic Ocean Freshening

“…living conditions in warming waters. Blooms of the North Atlantic calcifying algae Emiliania huxleyi have been observed to follow the ever-encroaching polar front (Neukermans et al, 2018) possibly advected there due to increased current velocities (Oziel et al, 2020).…”

Global drivers of eukaryotic plankton biogeography in the sunlit ocean

“…Under this scenario, the distribution of large long-lived generalist predators such as Copepods (Arthropoda) is expected to be stretched to the scale of currents systems through large-scale transport and mixing by main currents (Hellweger, van Sebille, & Fredrick, 2014; Lévy, Jahn, Dutkiewicz, & Follows, 2014; Madoui et al, 2017; Richter et al, 2019), and to be patchy as a result of small-scale turbulent stirring (Abraham, 1998). These contrasted views illustrate that little is known on how the interplay between body size, ecology, currents and the local environment shapes biogeography (Oziel et al, 2020).…”