Benthic Foraminifera Dynamics in Marine Sediments

Benthic foraminifera are single‐celled protists that inhabit the sea floor and play pivotal roles in sedimentary ecosystems and global biogeochemical cycles. Their calcareous tests record environmental conditions, making them indispensable proxies for palaeoceanographic reconstructions. In modern sediments, foraminifera influence carbon and nutrient fluxes through a combination of bioturbation, bioirrigation and microbial interactions. Many species possess adaptations to low‐oxygen or anoxic conditions, including anaerobic metabolism, intracellular nitrate storage and symbiotic associations with sulphur‐oxidising or photosynthetic microalgae. Such adaptations underlie their survival in oxygen minimum zones, sulfidic sediments and hypoxic coastal basins. Foraminiferal activity alters the redox state of porewaters, drives denitrification and affects the burial of organic carbon and calcium carbonate. Advances in imaging, molecular biology and modelling have elucidated the metabolic pathways that support foraminiferal resilience and quantified their contribution to nitrogen loss in sediments. As coastal deoxygenation and ocean acidification intensify, understanding the dynamics of benthic foraminifera is vital for predicting future shifts in marine nutrient cycling and benthic ecosystem function.

Research from Nature Portfolio

Recent studies have employed machine learning to quantify pore patterns in bolivinid foraminifera, revealing spatial variations in pore density and size that calibrate directly with bottom‐water nitrate concentrations and enable higher‐resolution reconstructions of deglacial and Holocene nutrient inventories. Complementary work has coupled measurements of foraminiferal test δ13C and pore density to reconstruct intermediate‐depth nitrate profiles in the Peruvian upwelling region, demonstrating tight coupling between past carbon and nitrogen cycles during deglacial transitions. In parallel, the surface area of gas‐exchange pores in epifaunal benthic foraminifera has been calibrated against modern bottom‐water oxygen measurements, establishing a robust proxy for deep‐sea palaeo‐oxygenation that applies across a broad bathymetric and geographic range.

Benthic Foraminifera Dynamics in Marine Sediments publication trend

The graph below shows the total number of articles in benthic foraminifera dynamics in marine sediments across all publications each year (not limited to Nature Index journals).

Technical terms

Denitrification: Anaerobic respiration process in which nitrate is reduced to nitrogen gas, mediated by microbes and some foraminifera.

Bioirrigation: Transport of oxygenated water and solutes into sediment porosity by the movement and feeding activity of benthic organisms.

Bioturbation: Reworking of sediment particles and microhabitats by the burrowing and feeding of organisms, altering sediment structure and geochemistry.

Kleptoplasty: Retention of functional chloroplasts by foraminifera after ingesting algal prey, enabling temporary photosynthetic activity.

Palaeo‐proxy: Biological, chemical or physical indicator preserved in sediments that records past environmental conditions.

References

1. A deep-learning automated image recognition method for measuring pore patterns in closely related bolivinids and calibration for quantitative nitrate paleo-reconstructions. Scientific Reports (2023).
2. Coupling of oceanic carbon and nitrogen facilitates spatially resolved quantitative reconstruction of nitrate inventories. Nature Communications (2018).
3. A New biological proxy for deep-sea paleo-oxygen: Pores of epifaunal benthic foraminifera. Scientific Reports (2018).
4. Array of metabolic pathways in a kleptoplastidic foraminiferan protist supports chemoautotrophy in dark, euxinic seafloor sediments. The ISME Journal: Multidisciplinary Journal of Microbial Ecology (2024).
5. Foraminiferal denitrification and deep bioirrigation influence benthic biogeochemical cycling in a seasonally hypoxic fjord. Geochimica et Cosmochimica Acta (2025).
6. Benthic foraminifera and gromiids from oxygen-depleted environments – survival strategies, biogeochemistry and trophic interactions. Biogeosciences (2023).