Microbial Eukaryote Community Dynamics

Microbial eukaryotes (or protists) comprise a diverse assemblage of single-celled organisms that drive fundamental processes in aquatic and terrestrial ecosystems. Their community dynamics encompass interactions such as predation, parasitism, symbiosis and nutrient recycling, typically regulated by environmental gradients of temperature, salinity, oxygen and substrate availability. Seasonal fluctuations and vertical stratification in water bodies create shifting niches in epilimnetic, metalimnetic and hypolimnetic zones, while benthic environments exhibit complex sediment–water coupling. High-throughput sequencing and molecular imaging techniques have revealed rapid successions in dominant taxa, from phototrophic groups fuelling primary production to heterotrophic grazers mediating carbon transfer. Protist-mediated processes such as grazing pressure and parasitism significantly influence microbial food-web structure and global biogeochemical cycles, particularly carbon export and nutrient regeneration. Understanding these dynamics is crucial for predicting ecosystem responses to climate change, managing water quality and harnessing microbial functions in biotechnological applications.

Research from Nature Portfolio

In polar oceans, analysis of DNA metabarcoding samples across five water masses in the western Weddell Sea has revealed an ecological succession of pico-nano eukaryotic communities. Surface waters are dominated by algae, bacteriovores and small-eukaryote predators; as water sinks and oxygen declines, parasitoids and mesoplankton predators emerge, highlighting strong depth- and oxygen-driven community structuring. Studies of carbon flux in the deep bathypelagic ocean have demonstrated the ubiquitous presence of healthy diatoms down to 4,000 m. Fast-sinking aggregates and faecal pellets deliver fresh phytoplankton cells to abyssal depths within days, confirming a prevalent mechanism of deep-sea carbon injection and its role in global carbon sequestration.

Microbial Eukaryote Community Dynamics publication trend

The graph below shows the total number of articles in microbial eukaryote community dynamics across all publications each year (not limited to Nature Index journals).

Technical terms

Protist: A diverse group of predominantly unicellular eukaryotes, including algae, protozoa and slime moulds.

Metabarcoding: A DNA-based method for identifying multiple taxa in environmental samples via high-throughput sequencing of marker genes.

Grazing: The consumption of microbial cells by protists, crucial for transferring energy and recycling nutrients in food webs.

Epilimnion: The warm, well-mixed upper layer of a stratified water body, often experiencing peak light and primary production.

Hypolimnion: The cold, dense lower layer in stratified waters, typically isolated from surface mixing and characterised by distinct communities.

References

1. Microbial eukaryotic predation pressure and biomass at deep-sea hydrothermal vents. The ISME Journal: Multidisciplinary Journal of Microbial Ecology (2024).
2. Community dynamics of microbial eukaryotes in intertidal mudflats in the hypertidal Bay of Fundy. ISME Communications (2023).
3. Integrating depth-dependent protist dynamics and microbial interactions in spring succession of a freshwater reservoir. Environmental Microbiome (2024).
4. Water masses shape pico-nano eukaryotic communities of the Weddell Sea. Communications Biology (2023).
5. Ubiquitous healthy diatoms in the deep sea confirm deep carbon injection by the biological pump. Nature Communications (2015).