Migrating is not enough for modern planktonic foraminifera in a changing ocean.

Rising carbon dioxide emissions are provoking ocean warming and acidification, altering plankton habitats and threatening calcifying organisms, such as the planktonic foraminifera (PF). Whether the PF can cope with these unprecedented rates of environmental change, through lateral migrations and vertical displacements, is unresolved. Here we show, using data collected over the course of a century as FORCIS global census counts, that the PF are displaying evident poleward migratory behaviours, increasing their diversity at mid- to high latitudes and, for some species, descending in the water column.

A solution for constraining past marine Polar Amplification.

Most climate proxies of sea surface temperatures suffer from severe limitations when applied to cold temperatures that characterize Arctic environments. These limitations prevent us from constraining uncertainties for some of the most sensitive climate tipping points that can trigger rapid and dramatic global climate change such as Arctic/Polar Amplification, the disruption of the Atlantic Meridional Overturning Circulation, sea ice loss, and permafrost melting. Here, we present an approach to reconstructing sea surface temperatures globally using paired Mg/Ca - δO recorded in tests of the polar to subpolar planktonic foraminifera Neogloboquadrina pachyderma.

Large-scale culturing of the subpolar foraminifera reveals tolerance to a large range of environmental parameters associated to different life-strategies and an extended lifespan.

The subtropical to subpolar planktic foraminifera is a calcifying marine protist, and one of the dominant foraminiferal species of the Nordic Seas. Previously, the relative abundance and shell geochemistry of fossil have been studied for palaeoceanographic reconstructions. There is however a lack of biological observations on the species and a poor understanding of its ecological tolerances, especially for high latitude genotypes.

Continuous reproduction of planktonic foraminifera in laboratory culture.

Planktonic foraminifera were long considered obligate sexual outbreeders but recent observations have shown that nonspinose species can reproduce by multiple fission. The frequency of multiple fission appears low but the survival rate of the offspring is high and specimens approaching fission can be distinguished. We made use of this observation and established a culturing protocol aimed at enhancing the detection and frequency of fission.

The global genetic diversity of planktonic foraminifera reveals the structure of cryptic speciation in plankton.

The nature and extent of diversity in the plankton has fascinated scientists for over a century. Initially, the discovery of many new species in the remarkably uniform and unstructured pelagic environment appeared to challenge the concept of ecological niches. Later, it became obvious that only a fraction of plankton diversity had been formally described, because plankton assemblages are dominated by understudied eukaryotic lineages with small size that lack clearly distinguishable morphological features.

Collection of X-ray micro computed tomography images of shells of planktic foraminifera with curated taxonomy.

Calcite shells of planktic foraminifera (Protista, Rhizaria) constitute a large portion of deep-sea sediments. The shells are constructed by sequential addition of partly overlapping chambers with diverse shapes, resulting in complex shell architectures, which are genetically fixed and diagnostic at the species level. The characterisation of the complete architecture requires three-dimensional imaging of the shell, including the partially or entirely covered juvenile chambers.

Large-scale culturing of , its growth in, and tolerance of, variable environmental conditions.

The planktic foraminifera is a calcifying marine protist and the dominant planktic foraminifera species in the polar oceans, making it a key species in marine polar ecosystems. The calcium carbonate shells of foraminifera are widely used in palaeoclimate studies because their chemical composition reflects the seawater conditions in which they grow. This species provides unique proxy data for past surface ocean hydrography, which can provide valuable insight to future climate scenarios.

Uncovering hidden structures: previously undescribed pseudopodia and ectoplasmic structures in planktonic foraminifera.

The trophic strategies of cold-water planktonic foraminifera are not well understood due to the challenge of culturing them in polar conditions. Here, we identify previously unknown ectoplasmic and cytoplasmic projections in three species of planktonic foraminifera thriving in polar and subpolar marine environments: , and . These structures were observed during routine monitoring of cultured specimens sampled from the Norwegian coast, Greenland Sea and Baffin Bay.

The FORCIS database: A global census of planktonic Foraminifera from ocean waters.

Planktonic Foraminifera are unique paleo-environmental indicators through their excellent fossil record in ocean sediments. Their distribution and diversity are affected by different environmental factors including anthropogenically forced ocean and climate change. Until now, historical changes in their distribution have not been fully assessed at the global scale.

Isotopic evidence for an intensified hydrological cycle in the Indian sector of the Southern Ocean.

The hydrological cycle is expected to intensify in a warming climate. However, observational evidence of such changes in the Southern Ocean is difficult to obtain due to sparse measurements and a complex superposition of changes in precipitation, sea ice, and glacial meltwater. Here we disentangle these signals using a dataset of salinity and seawater oxygen isotope observations collected in the Indian sector of the Southern Ocean.

Morphology, genome plasticity, and phylogeny in the genus ostreococcus reveal a cryptic species, O. mediterraneus sp. nov. (Mamiellales, Mamiellophyceae).

Coastal marine waters in many regions worldwide support abundant populations of extremely small (1-3 μm diameter) unicellular eukaryotic green algae, dominant taxa including several species in the class Mamiellophyceae. Their diminutive size conceals surprising levels of genetic diversity and defies classical species' descriptions. We present a detailed analysis within the genus Ostreococcus and show that morphological characteristics cannot be used to describe diversity within this group.