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The Quaternary glaciations profoundly shaped the biogeography of plants and animals, yet their impact on microbial eukaryotes remains largely unexplored. We tested the “genetic legacy of the Quaternary” (GLQ) paradigm in terrestrial protists using Arcellinida testate amoebae diversity distribution across the Iberian Peninsula, a well‐established glacial refugium. To do so, we compiled the most extensive Arcellinida metabarcoding dataset to date (ArKOI), including 615 samples from multiple continents and ecosystems. Our results showed that hotspots of intra‐OTU genetic diversity align with known Iberian refugia, supporting the concept of “refugia within refugia,” and displaying clear ecoregion‐specific climatic niches. Patterns of spatial clustering, niche breadth, and historical demographic reconstruction revealed repeated range contractions and expansions during the Pleistocene, mirroring those observed in macro‐organisms. These findings extend the GLQ paradigm to protists, highlighting shared historical and ecological processes across the eukaryotic tree of life and contributing to a unified theory of biogeographic responses to climatic change.

Climate change models point to a possible rise in air temperature, ranging from 2 °C to 4 °C. Global changes will therefore have a particularly pronounced effect on the functioning of shallow water bodies known as peat ponds, i.e., habitats formed after peat extraction in peatlands. However, the extent of this impact is still unknown. The main objective of the study was to determine the impact of water level and water physicochemical properties on the functioning of selected groups of aquatic organisms in peat ponds of different origins. The study was conducted in spring, summer and autumn of the years 2024 and 2025, in 10 peat ponds with different trophic status and typology, located in the Polesie National Park in eastern Poland. Considerable fluctuations in water levels, resulting from a scarcity of precipitation, accelerated the drying out and overgrowth of peat ponds, particularly the alkaline and acidic types. Within the zoocoenotic communities, a significant decline in the abundance of planktonic species and an increase in the abundance of littoral or periphytic species were recorded (F = 6.24, p < 0.015). Regarding trophic structure, an increase in the abundance of mixotrophic species and a decrease in the abundance of top-level predators were observed. Hydrological changes were reflected in an increase in species richness and abundance of communities of organisms with broad ecological tolerance (mainly ciliates), and a decrease in the number of species and abundance of planktonic crustaceans and macroinvertebrates. The RDA model explains over 84% of the total variability, indicating excellent model fit to the data and a strong correlation between environmental variables and species composition. Based on p values, water level, temperature, pH, and COD were selected as significant variables, with conductivity, O2, and Ptot demonstrating less statistical significance. Peat ponds ecosystems can serve as an excellent model system for studying the impact of intensifying climate change on the functioning of shallow water bodies.

Testate amoebae are known among the proxies for paleolimnological investigations but, despite their recognized importance and recent findings, they have not been sufficiently studied in alpine lakes, particularly in Europe. The present study analyzes fossil testate amoeba assemblages from the Upper Balma Lake (2216 m a.s.l., Western Alps, Italy) to reconstruct ecological changes over the past 1200 years. 21 species belonging to 5 genera were identified, with Centropyxis and Difflugia being the most abundant. Multivariate statistical analyses, combined with sedimentological and geochemical data, revealed five paleoenvironmental phases corresponding to known climatic events, including the Medieval Climate Anomaly, the Little Ice Age, and the Recent Warming period. Assemblage composition and diversity were related to grain size variations, nutrient input, and trace element concentrations (e.g., As, Mn, Mo) and periods of climatic stability were associated with higher biodiversity, while cold or disturbed intervals, marked by floods or sediment reworking, resulted in reduced abundances and diversity. In recent decades, a decline was observed for the genus Centropyxis , possibly indicating reduced oxygenation and changes in contaminant levels. Comparative analysis with the Lower Balma Lake, located downstream in the same area, highlighted the influence of morphological/hydrological differences between lakes on species distributions. The findings underscore the value of testate amoebae as sensitive bioindicators and their applicability in paleoecological reconstructions of alpine lakes. This study contributes to understanding long-term ecological responses to climate change and provides insights into flood regime variability in high-mountain environments.

Peatlands are susceptible not only to direct disturbance, but also to indirect changes in their surroundings, including land management. Changes in agricultural practices or forest management can significantly influence peatland functioning, for example, their trophic status or surface vegetation. Here, we investigate the effects of planned forestry on two Sphagnum -dominated peatlands in northern Poland’s Tuchola Forest. We use testate amoebae and compare them to available pollen and historical data to reconstruct past environmental conditions and assess anthropogenic pressure. The Tuchola Forest has undergone significant transformations as a result of human activities, notably during Prussia’s promotion of pine monoculture in the 19th century. We hypothesized that forest management activities and other related disturbances have led to wetland acidification and water table alterations. Our results show that these changes have had profound effects on both peatlands. Radiocarbon dating revealed a correlation between forest management practices and peatland dynamics. Quantitative reconstructions based on testate amoebae showed that, as a result of the introduced pine monoculture, both peatlands experienced rapid acidification (pH levels dropping from ca. 6.2 to 3.5) and water table lowering of over 15 cm. The predominance of pine monoculture has not only reduced biodiversity but also enhanced the susceptibility of the forest to fires and pest outbreaks, further affecting peatland conditions. These findings contribute to understanding of how historical land-use changes continue to influence present-day peatland dynamics, offering insights into restoration and conservation efforts in forested peatland landscapes.

Abstract. This study investigates the vegetation and hydrological dynamics of Linje peatland in northern Poland during the past ∼11 500 years by integrating testate amoebae and plant macrofossil analyses. The Linje profile is currently the only complete Holocene peat record in Central Europe and offers valuable insights into long-term climate variability and its ecological consequences for peatland ecosystems. The results reveal significant changes in peatland wetness and vegetation driven by autogenic processes, climatic fluctuations and anthropogenic influences. Major bryophyte species turnovers occurred ∼11 200, ∼10 350, ∼8200, 7500, ∼5500, ∼600, and ∼450 cal BP often coinciding with declines in Archerella flavum and Hyalosphenia papilio abundances. Both proxies indicate a marked period of drier conditions between ∼ 7600 and ∼ 6800 cal BP corresponding with the Holocene Thermal Maximum. Additionally, testate amoebae data suggest further disturbances at ∼ 3050, ∼ 2000, and ∼ 200 cal BP, and the latter, linked to a permanent shift in species composition, implies lasting changes to peatland conditions caused by intensified human activity. Around the end of the Early Holocene, most species turnovers and disturbances began to align with Holocene Rapid Climate Change (RCC) events.

Testate amoebae belong to the single celled organisms classified under protist fauna characterized by developing complex covering of outer chitin shells; they are renowned as bio indicators owing to their high reactivity to any change in the environment. This communication reports 2 new additions of moss inhabitant micro fauna to Indian testate fauna viz., Arcella costata Ehrenberg, 1847 and Trinema lenticularis Siemensma et Lucow, 2025, from Wayanad Wildlife Sanctuary, Kerala.

Multi-proxy approaches in palaeoecological studies have gained prominence due to their ability to provide comprehensive insights into palaeoenvironmental changes. This method enhances the complexity and richness of environmental reconstructions by integrating various proxies, such as testate amoebae, pollen, plant macrofossils, charcoal, and stable isotopes. While synthesising these records can be challenging, due both to their complexity and varying journal guidelines for publication, it remains essential for a more precise understanding of past ecosystems. Multi-proxy studies are invaluable for cross-referencing local to extra-local data with proxies from nearby areas, thus validating palaeoclimatic records and minimising speculative conclusions. The approach reveals significant human impacts on ecosystems, particularly peatlands, serving as natural archives for historical environmental and anthropogenic activities. Integrating diverse methodologies from ecology, palaeoecology, archaeology, and history with high-resolution palaeoecological data offers profound insights into settlement patterns, economic development, and historical demography. Despite the challenges of handling extensive datasets, advanced statistical methods enable meaningful interpretations while maintaining the integrity of the data. Historical records enrich the understanding of human and climatic impacts upon a range of peatland ecosystems. By reconstructing long-term changes in food webs through peat records, researchers can gain a deeper understanding of past ecosystem structures and functions, thereby paving the way for future ecological advances. Though underutilised in archaeological and historical contexts, this interdisciplinary approach has significant potential across various academic fields, emphasising the importance of integrating comprehensive datasets to approach complex ecological questions and inform ecological restoration. This review presents the potential of high-resolution, multi-proxy studies of peatlands, shows examples of such studies and summarises best practices and key considerations for conducting such research.

Testate amoebae are a polyphyletic and highly diverse group of unicellular protists, inhabiting various habitats and successfully used as indicators of property of environmental variables, providing information on hydrology, pH and pollution of ecosystems. However, despite numerous studies, there is still a lack of data regarding their species diversity, geographical distribution and population dynamics in various habitats from previously unexplored or poorly investigated regions such as Mongolia. In this study, we describe the morphology and morphometry of a new genus and four new species: Armatura murmillo gen. nov., sp. nov., Trinema lenticularis sp. nov., T. parmularius sp. nov. and T. scutarius sp. nov., derived from peat cores extracted from two fens in northern Mongolia. We provide one of the first case studies of testate amoebae from Mongolia, documenting 64 taxa. We also provide information on the morphology and variability of four lesser known species: Centropyxis lapponica, Hyalosphenia insecta, Pyxidicula ornata and Schoenbornia smithi.

The epiphytic bryophytes as a microbial habitat on trees in terrestrial environment holds diverse microscopic organisms. These moss habitats are suitable for testate amoebae which are bioindicators of envirornment. The present investigation on testate amoebae population in tree mosses, collected during various surveys from Parambikulam Tiger Reserve, Kerala and Taluka, Uttarakhand. The study recorded two species of testate amoebae viz., Centropyxis bipilata Bakovic et al., 2019 and Paraquadrula discoides (Penard, 1893) Deflandre (1932) are new additions to Indian testate fauna.

Abstract. Northern peatlands are significant terrestrial carbon stores but are increasingly threatened by human activities. Ombrotrophic peatlands, being naturally acidic, are particularly vulnerable to alkaline pollution. Despite their importance, the effects of alkalinisation on peatlands remain insufficiently studied. In Estonia, alkaline pollution from a cement industry and oil shale power plant emissions have degraded several peatlands since the 19th century. Although some sites have recovered in recent decades, more severely impacted areas remain in poor condition. We investigated the effects of alkalinisation on Varudi peatland, a forested site in northeast Estonia, which was exposed to 125 years of alkaline emissions from a nearby cement factory. Using a multi-proxy, high-resolution palaeoecological approach combined with a precise and reliable age-depth model, we reconstructed changes in environmental, chemical, botanical, and hydrological conditions over the past millennium. Our findings revealed three successional phases: during the mid-13th century CE, land clearance and increased mineral deposition caused the site to transition from a bog to a poor fen phase between approximately 1250–1570 CE; and while the cement factory operated without efficient filters, the site became a pine-dominated fen between 1871–1995. After the installation of filters in 1996, peatland pH returned to near pre-disturbance levels, and some recovery was observed. However, the site remains degraded. Our results indicate that alkalinisation significantly disrupts peatland functioning, reducing carbon storage and altering vegetation communities. These effects can persist for decades even after the source of contamination is removed, underscoring the need for more comprehensive monitoring of peatlands impacted by alkaline pollution globally.