Testate Amoebae Ecology and Peatland Hydrology

Testate amoebae are unicellular protists encased in a shell or “test” that occupy diverse microhabitats within peatlands. Their distributions and community compositions respond sensitively to the depth of the water table, pH, nutrient availability and microclimate. Peatlands themselves are globally significant carbon stores, where hydrological regime governs the balance between carbon sequestration and emission. By analysing testate amoeba assemblages preserved in peat cores, researchers can reconstruct past water-table fluctuations over centuries to millennia. Such reconstructions inform our understanding of hydrological resilience, autogenic feedbacks and the impacts of climate change and land-use shifts on peatland function. Beyond palaeoecology, living testate amoebae influence peatland carbon cycling through grazing, mixotrophy and interactions with Sphagnum mosses. Transfer functions—statistical models linking modern testate amoebae to measured hydrological variables—provide the quantitative framework for these studies. Together, these approaches underpin both fundamental ecology and applied conservation, guiding peatland restoration and informing climate-mitigation policies.

Research from Nature Portfolio

Functional traits of testate amoebae have been shown to serve as mechanistic proxies for past disturbances in Sphagnum-dominated peatlands. By analysing trait shifts such as cell size, aperture morphology and nutritional strategy, researchers demonstrated that mixotrophy and certain shell features reliably signal fires and peat extraction over the last two millennia.

Experimental warming in field and microcosm settings has revealed the pivotal role of mixotrophic testate amoebae in peatland carbon cycling. Five years of summer temperature increases led to a halving of dominant mixotroph biomass, with consequent reductions in net carbon uptake by the Sphagnum bryosphere, underscoring the vulnerability of this functional group to climate warming.

Testate Amoebae Ecology and Peatland Hydrology publication trend

The graph below shows the total number of articles in testate amoebae ecology and peatland hydrology across all publications each year (not limited to Nature Index journals).

Technical terms

Testate amoebae: unicellular protists enclosed in a protective shell, used as bioindicators of peatland water-table depth.

Peatland hydrology: the study of water movement and storage within peat-forming wetlands that regulate carbon exchange.

Transfer function: a statistical relationship linking modern species assemblages to environmental variables for reconstructing past conditions.

Functional traits: morphological or physiological characteristics of organisms that influence their ecological roles and responses.

Mixotrophy: a nutritional strategy combining photosynthesis and ingestion of prey, common in certain testate amoebae.

Water-table depth: the position of the saturated zone in peat, which determines redox conditions and biogeochemical processes.

References

1. Assessing the impact of forest management and climate on a peatland under Scots pine monoculture using a multidisciplinary approach. Biogeosciences (2024).
2. Testate Amoeba Functional Traits and Their Use in Paleoecology. Frontiers in Ecology and Evolution (2020).
3. A novel testate amoebae trait-based approach to infer environmental disturbance in Sphagnum peatlands. Scientific Reports (2016).
4. An unexpected role for mixotrophs in the response of peatland carbon cycling to climate warming. Scientific Reports (2015).
5. Untangling climate signals from autogenic changes in long‐term peatland development. Geophysical Research Letters (2015).
6. Towards a Holarctic synthesis of peatland testate amoeba ecology: Development of a new continental-scale palaeohydrological transfer function for North America and comparison to European data. Quaternary Science Reviews (2018).