Planktonic Foraminifera in Oceanic Environments

Planktonic foraminifera are single-celled protists with calcareous shells that drift through the surface and subsurface layers of the world’s oceans. Their finely layered tests capture chemical signals—such as oxygen and carbon isotopic ratios and elemental composition—that make them essential proxies for reconstructing past sea surface temperature, salinity and carbonate chemistry. These organisms contribute significantly to the marine carbon cycle via biogenic calcification and vertical carbon export. Species exhibit distinct depth habitats and seasonal flux patterns, reflecting adaptations to temperature gradients, nutrient availability and symbiotic relationships. Global diversity spans tropical oligotrophic gyres to polar waters, with emerging molecular surveys revealing cryptic lineages masked by simple morphology. Modern research integrates sediment traps, plankton tows, high-resolution sediment records and molecular techniques to unravel how foraminiferal assemblages respond to natural climate oscillations and anthropogenic perturbations. Insights into their biogeography, calcification dynamics and evolutionary diversification inform climate model calibration and predictions of biogenic carbonate flux in a warming, acidifying ocean.

Research from Nature Portfolio

Analyses of planktonic foraminiferal assemblages from Last Glacial Maximum sediments reveal a steeper thermal gradient in the subpolar North Atlantic than is simulated by many climate models. By applying macroecological principles of species turnover and temperature dependence, researchers have shown that uniform cooling in model outputs underestimates regional cooling, highlighting the need for improved representation of ocean circulation and spatially variable climate change in palaeoclimate simulations.

Centuries-spanning sediment cores from the Mediterranean Sea demonstrate that rising atmospheric carbon dioxide has driven basin-wide reductions in shell weight and foraminiferal calcification. Isotopic records of carbon and boron confirm the growing influence of fossil fuel CO₂ and ocean acidification, while concurrent warming and productivity shifts prove insufficient to counter declines in biogenic carbonate production, forecasting continued impacts under future CO₂ rise.

Planktonic Foraminifera in Oceanic Environments publication trend

The graph below shows the total number of articles in planktonic foraminifera in oceanic environments across all publications each year (not limited to Nature Index journals).

Technical terms

Biogenic calcification: The biologically mediated formation of calcium carbonate shells by marine organisms.

Macroecology: The study of large-scale patterns and processes governing the distribution and diversity of ecological communities.

Metabarcoding: High-throughput sequencing of environmental DNA to identify and quantify species in complex assemblages.

Cryptic species: Distinct genetic lineages that are morphologically similar and often unrecognised by traditional taxonomy.

Molecular operational taxonomic unit (MOTU): A cluster of DNA sequences grouped by similarity, used as a proxy for species in molecular surveys.

Stable oxygen isotopic ratio (δ18O): The proportion of heavy to light oxygen isotopes in carbonate tests, used to infer past temperature and salinity conditions.

References

1. The global genetic diversity of planktonic foraminifera reveals the structure of cryptic speciation in plankton. Biological Reviews (2024).
2. Strong temperature gradients in the ice age North Atlantic Ocean revealed by plankton biogeography. Nature Geoscience (2023).
3. Anthropogenic acidification of surface waters drives decreased biogenic calcification in the Mediterranean Sea. Communications Earth & Environment (2023).
4. The FORCIS database: A global census of planktonic Foraminifera from ocean waters. Scientific Data (2023).
5. Coherent response of zoo‐ and phytoplankton assemblages to global warming since the Last Glacial Maximum. Global Ecology and Biogeography (2024).