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The exploitation of peatlands in Estonia, which began in the 17th century, has degraded them to a great extent. Consequently, cutover and drained peatlands have become the sources of CO2. Global warming has led to a need for policies focusing on the protection and restoration of drained and degraded peatlands. Hence, to compare the effect/progress of restoration with the past pristine ecosystem baseline before the peatland was destroyed by cutting, we examined a peat core from North Estonia using chronology based on 14C by analyzing several proxies in high resolution including testate amoebae, plant macrofossils, pollen, non-pollen palynomorphs, and diatoms. The results revealed a striking ecological contrast between the pristine (ca. 2 kyrs) and restored state (currently) of the peatland. The pristine state was characterized by a domination of Sphagnum fuscum/rubellum and Archerella flavum, suggesting that extraction area of Hara peatland was a wet and stable ombrotrophic bog. As a result of peat exploitation, deposits comprising the last ca. 2 kyrs were cut. In turn an important feature of the restored section of the peat core was the domination of a green algae (Chlorophyta) and Eriophorum vaginatum as well as testate amoebae species Arcella discoides, which is considered an indicator of hydrological instability. The main difference between the predisturbed and restored parts of the peat core section was that a minor cover of peat-forming Sphagnum and mixotrophic testate amoebae was present in the top inundated part. We state that a healthy raised bog—the target of restoration—should consist abundant mixotrophic testate amoebae such as Archerella flavum and Hyalosphenia papilio which are good indicators of a well-functioning Sphagnum bog ecosystem even if the Sphagnum species differ from the reconstructed ecological baseline conditions. Our study highlights the extensive damage caused to the peat-forming ombrotrophic peatland by extraction and how difficult, challenging, and time-consuming is the process of ecological restoration.

La Trobe University Faculty of Science, Technology and Engineering Murray Darling Freshwater Research CentreMDFRC item.Coastal lagoons of the principal islands of Bass Strait, between Australia's mainland and Tasmania, were sampled in two summers. Many, particularly those of low to moderate salinity, contain relatively rich assemblages of microinvertebrates and some endemic Australian freshwater algae. Several species of testate amoebae and rotifers could not be referred to known morphotypes and are probably new species. The presence of certain species on islands of Bass Strait provides a link between populations in mainland Australia and others in Tasmania. Those lagoons are identified that, by virtue of catchments or buffer zones clothed in native vegetation, are favourable for the survival of a native and partly endemic microbiota.

Testate amoebae are single-celled protists whose protoplasm is contained within a carapace composed of gelatinous to imbricated chitinous plates having variable chemical compositions. We inventoried the testate amoebae community present in the plankton and periphyton of the Pantanal dos Marimbus swamp in Bahia state, Brazil. Sixty-five samples of plankton and periphyton were analyzed during May and September/2014 and April/2015. We identified 65 taxa of testate amoebae distributed in eight families, 15 genera, 45 species, and 16 varieties. The most representative families were Arcellidae, Centropyxidae, and Difflugiidae, corresponding to 24.6%, 19.7% and 14.8% of the taxa respectively. The periphyton had greater richness (59 taxa) than the plankton (39 taxa). Of the taxa found, 15 represent new records for Bahia and 14 for northeastern Brazil. The Marimbus Pantanal swamp showed an expressive richness of testate amoebae, and our data increases the number of species of these organisms known to Bahia and northeastern Brazil, where work with those organisms is still scarce.

Peatland complexes in the humid highlands of Hawai‘i are vital refuges of biodiversity and freshwater resources. Hawaiian peat deposits are also rare repositories of terrestrial ecosystem archives located in an otherwise vast expanse of ocean. We investigated the potential for researching the paleohydrological history of Hawaiian montane peatlands on Kohala, Hawai‘i Island through analyses of testate amoebae and Cladocera. Surface peat was collected from a variety of ecohydrological habitats (from water pools to hummocks) and analyzed for modern testate amoeba and cladoceran species relative abundance. We identified 54 morphotype taxa from 21 genera of testate amoebae, 4 taxa and genera of littoral Cladocera, and the common peat rotifer Habrotrocha angusticollis. Testate amoeba diversity and morphotype occurrence mirrored observations from many high-latitude peatland studies. Constrained and unconstrained ordinations support the hypothesis that surface moisture, measured as water-table depth, is an important control on the distribution of testate amoebae and Cladocera in Hawaiian peatlands. Transfer functions relying on weighted-averaging and modern analogs were developed to predict water-table depths from species relative abundance data, and these perform well under leave-one-site-out cross-validation: RMSEP = 9.75–10.3 cm, R2 = 0.56–0.62. Including cladoceran abundance data in the calibration dataset produced modest model improvement: RMSEP = 1–8% and R2 = 2–13%. A weighted-average partial-least-squares transfer function was applied to microfossil assemblages from a 0.5 m-long peat core with a 210Pb decay chronology anchored by ten existing measurements of 210Pb activity and a Bayesian statistical framework. Microfossils were well-preserved in the peat core. The water-table depth optima of an abundant down-core taxa, Hyalosphenia subflava, is not precisely constrained in the calibration data set, but estimates match those of other tropical studies. A reconstruction of water-table depth indicates dry early nineteenth-century conditions, wet conditions in the late 19th to early twentieth centuries, followed by progressive drying for much of the twentieth-century. Testate amoeba composition appears to have been sensitive to severe drought in recent decades. The results signal that assemblages of testate amoebae and Cladocera are useful proxies of Hawaiian peatland paleohydrology and should be considered alongside other archives of Hawaiian environmental history.

We present a ~ 40–year record of environmental change in the Swan Oxbow, Yangtze River, China, inferred from testate amoeba and sedimentary pigment data, combined with remote sensing and analysis of local socio–economic growth. These data indicate there were several distinct phases of aquatic conditions linked to human activities in the region: (1) Between ca. AD 1970 and 1984, there may have been some exchange of water and organic matter between the Swan Oxbow and the main river channel, following initial hydrologic disconnection in 1972. The lake area was relatively large in the early phase after the oxbow first formed, and the trophic state generally increased during that time frame, (2) From ca. AD 1984 to 1992, the lake area was about a third smaller in size, while the human population and GDP increased about 10% and 10x, respectively, compared to values in 1975. The nutrient status (inferred from testate amoeba and pigment data) increased, owing to the greater discharge of nutrients and separation of the Swan Oxbow from the main Yangtze River, which reduced water supply and increased sedimentation in the oxbow, (3) From ca. AD 1992 to 2003, the lake continued to diminish in size, to an area

The main objective of the study was to reconstruct palaeoenvironmental changes recorded in lake and peatland sediments from the peatland located in the western part of Lublin Polesie, where no former palaeoecological research had been conducted, and to compare findings to changes reconstructed for other sites in the eastern part of this region. Climate changes were considered, as well as the effects of human impact, which intensified particularly after the Middle Ages. In recent times the trajectory of change of the Mytycze ecosystem was exceptional because in the 1960s this area was included in the Wieprz-Krzna Canal System, and then renaturated after the discontinued use of hydraulic engineering structures. This is the largest canal in Poland and runs in the immediate vicinity of the watershed supplied by two large rivers: the Bug and the Wieprz. The presented study mainly relied on the following proxies: pollen, testate amoebae and other non-pollen palynomorphs, and peat decomposition. Data from the Archaeological Picture of Poland (AZP) allowed for a detailed reconstruction of chronological changes in the palaeoenvironment. An important aspect of this study was also the first ever use of testate amoebae remains in the reconstruction of the Lublin Polesie environment. Findings from research on the Mytycze site for the first time confirmed that the beginning of the formation of the lake basin was similar to that reconstructed for all other lakes in the Lublin Polesie region investigated previously with multidisciplinary methods, and dates to the end of the late glacial of the Vistulian. The early phase of the peatland formation resulting from the shallowing of the lake was very long and lasted from the Subboreal period to the 15th century. The youngest phases with records of human impact are characterised by increased human pressure (intensified cultivation of cereals, buckwheat, legumes and brassica crops) after the Wieprz-Krzna Canal System was put into use, and intensified grazing in the vicinity of Lake Mytycze. This phase, dated to the 1970s, is followed by a marked increase in the water level, which was probably related to the supply of water to the dammed Lake Mytycze from Wieprz-Krzna Canal via Lake Dratow. Records in the upper part of the core indicate the return of Sphagnum spp., most likely due to the cessation of the use of hydraulic engineering structures and the renaturation of the lake and peatland ecosystem, which led to the appearance of valuable species of plants and birds.

The present study aimed to explore the effect of a range of moisture content levels, including 65%, 72%, and 78%, on physicochemical properties and microfauna communities during vermicomposting of municipal sludge. As a result, death of perishable microfauna together with the degradation of organic matter was the dominant response in all groups in the early period of vermicomposting, while the effects of moisture content levels on various physiochemical parameters did not appear until the mid-later period. After the treatment with 78% moisture content, the content of mineral nitrogen was 1.186 g/kg in the sludge, with a 9.36 × 103 ind./g of microfauna quantity and 663.01 g of earthworm biomass. The values of these three measurements in 78% group were significantly higher than other two groups (p < 0.05), indicating that the effects of 78% moisture content were more pronounced for promoting nitrogen mineralization as well as microfauna and earthworms growth during vermicomposting. Specifically, testate amoebae were strongly associated with nitrification process, while nematodes were related to ammonification and phosphorus mineralization, of which testate amoebae had great potential of being bioindicators during vermicomposting of municipal sludge.

The policy and practice of ecological restoration and conservation in China obtained some remarkable results. For example, Sphagnum moss growing on abandoned farmland, which was peatland before agricultural use, has rapidly expanded the wetland area in SW China. Microorganisms such as testate amoebae are sensitive to environmental change and thus have been widely used as ecological indicators in various habitats. We analyzed differently aged Sphagnum growing plots on a Sphagnum growing farmland and natural Sphagnum plots in SW China to examine how Sphagnum-dwelling testate amoeba communities and corresponding protozoic silicon (Si) pools respond to ecological restoration practice. We found that abundance, taxon richness, and diversity of testate amoebae were higher in Sphagnum growing farmland plots compared to natural Sphagnum plots. Protozoic Si pools showed an increase with Sphagnum growing time representing increased Si accumulation by idiosomic testate amoeba shells. However, protozoic Si pools were negatively correlated with taxon richness and diversity of testate amoebae. Our results showed that (i) natural Sphagnum plots were not characterized by the expected higher biodiversity of testate amoebae compared to Sphagnum growing plots and (ii) consequently protozoic Si pool quantity in natural Sphagnum plots was less driven by biodiversity of testate amoebae than expected. We concluded our results to underline the value of (i) environmental restoration policy in general and (ii) testate amoeba communities and corresponding protozoic Si pools for Si cycling in restoration areas of peatlands in particular. Based on our results, we recommend a sustainable cultivation of Sphagnum moss and an additional establishment of protected areas, where no Sphagnum harvesting occurs. These protected Sphagnum areas might represent hot spots of undisturbed testate amoeba communities and corresponding protozoic Si pools and thus of microbial Si cycling.

Testate amoebae are a highly diverse and polyphyletic group of heterotrophic, free-living amoeboid protists that consist of a single cell enclosed within a shell, or test. These organisms i...

Testate amoebae are an irreplaceable key component of microbial communities in many aquatic and soil ecosystems and well known as useful bioindicators. In the present work, testate amoebae compositions in different-type biotopes of freshwater waterbodies of North Vietnam were investigated for the first time. A total of 80 species and subspecies belonging to 12 genera and 8 families were identified from 105 samples collected in Suoi Hai, Xuan Khanh, Cam Quy, Ho Ba reservoirs, and Van Long wetland. Difflugia acutissima, D. brychtai, D. distenda, D. elegans teres, D. glans, and Awerintzewia cyclostoma were new records for Vietnam. Centropyxis aculeata, D. schurmanni, and D. elegans were the most common species in all types of biotopes including plankton, benthos, and periphyton. The results of two-way ANOVA showed statistically significant interaction effects of waterbodies and the type of biotopes on testate amoebae species richness per sample (p

The Arctic is experiencing substantial warming with possibly large consequences for global climate when its large soil carbon stocks are mobilized. Yet the functioning of permafrost peatlands, which contain considerable amounts of carbon, is still not fully understood. Palaeoecological studies may contribute to unravelling this functioning but require actuo-ecological calibration of the environmental proxies used. Testate amoebae may be valuable proxies for palaeoecological reconstruction, but indeed still large gaps exist regarding their present-day distribution in Arctic peatlands. This study presents the distribution of testate amoebae taxa with high (1 m) spatial resolution along a transect crossing an Arctic ice-wedge polygon mire. Whereas the polygon ridges are characterised by taxa that are known to be typical of dry environments or hydrologically indifferent, the low-lying wet settings show a mixture of wet- and dry-living taxa, indicating seasonally rapidly changing conditions. High testate amoebae concentrations were only found on the dry polygon ridges. Archerella flavum occurs in various moss species in drier polygon settings, in contrast to temperate regions where the species is exclusively known from wet sites with Sphagnum, which probably relates to the special moisture conditions associated with permafrost. To compare the results of full testate amoebae analysis with those of palynology, each surface sample was split into two parts and prepared and analysed following standard testate amoebae analysis and palynological methods, respectively. Clear differences in qualitative content were found and can be attributed to the different preparation methods and to possible small (a few cm) differences in sample location. Nevertheless, the indicative value of testate amoebae found in pollen samples adds importantly to the ecological inference of palynological studies. Overall testate amoebae research is very valuable for the recognition of past ecological settings and the accurate reconstruction of past hydrological regimes in Arctic mires. Considerably more research is, however, necessary to cover the total (ecological) diversity of testate amoebae populations in NE Siberia.

This paper presents the results of multiproxy research (pollen, charcoal, plant macrofossil and testate amoebae) on the biogenic deposits core from Gorodetsky Moch, an ombrotrophic peatland in western Russia (Western Dvina Lakeland). We reconstructed the impact of disturbance on peatland development in the last 300 years by using chronology of the records based on14C and210Pb data set. The multiproxy reconstruction was compared with changes in the land cover using historical maps and Corona images, which provides a unique spatial analysis of past ecological and land-use changes. We aimed to determine the effect of local disturbances (drainage) and land-use changes (landscape openness) on the development of the peatland during the last 300 years. Our study suggests that human activity had a crucial impact on the development of the peatland in the last centuries. The analysis of testate amoebae and plant macrofossils revealed a clear disturbed layer in the second half of the 20th century CE. Most probably, the drainage of the peatland triggered changes in the community of testate amoebae and plants, thereby causing a functional shift in Sphagnum peatland ecosystem. The hydrological stress and vegetation composition shift led to the collapse of mixotrophic testate amoebae. However, the peatland showed strong resilience and recovered toward the end of the 20th century CE and the beginning of the 21st century CE, despite the lower water table. Our study shows an example of the peatland ecosystem that experienced a considerable stress but finally sustained the former function.

Rain-fed granite rock pools are geological landforms with a worldwide distribution. However, their role as habitats for microorganisms has been barely explored. We carried out a detailed morphological inventory of the ciliated protists in the sediments of three granite rain-fed rock pools from a Spanish National Park. The ciliate seed bank in the rock pools comprised 54 morphospecies. The species number inferred for each pool by rarefaction analysis was similar to that observed by microscopy. The most representative species were small bacterivorous ciliates, although the distribution of ciliate groups was significantly different in each rock pool. Testate amoebae were also found to be rich in species. This study demonstrates the existence of a diverse ciliate community adapted to persist in these ephemeral and extreme rock pool habitats through species resistance structures, many of which have not been described previously. The presence of competitive species in dormant stages prevents local extinctions through a sequential excystation over time. Our results provide a benchmark for studying protist and microbial biodiversity within rain-fed granite rock pools, a unique habitat that merits bio- and geo- conservation.

Large biological diversity can be observed in floodplains, which is linked to several ecosystem processes, such as productivity and nutrient cycling; among the species involved in these processes are zooplanktonic organisms. Here, we aimed to quantify the temporal trend of zooplankton, through changes in species richness and composition (β-diversity) and the abundance of individuals, in preserved and non-preserved sites of the Upper Parana River floodplain during the last 19 years, and 617 species (321 rotifers, 135 testate amoebae, 107 cladocerans, and 54 copepods) were recorded. The highest species richness was verified in 2002 and the lowest in 2016. Zooplankton richness and abundance in non-preserved sites show clear temporal homogenization, while preserved sites show cyclical fluctuations over time. The rarefaction curve showed the biodiversity potential in this floodplain. Three invasive species were recorded ( Kellicottia bostoniensis , Daphnia lumholtzi , and Mesocyclops ogunnos ). The variation in the hydrologic regime, the oligotrophication, and the reduced connectivity among the sites were the main factors interfering in the species composition over the years and leading to a reduction of the species richness and abundance. The preservation of the tributaries with pristine characteristics is very important for the mitigation of these synergistic effects under the community structure.

In this article, we examined the indicative value of a relationship between two non-pollen palynomorphs (NPPs), fungal HdV-10, related to the presence of Calluna vulgaris, and HdV-31A, which is testate amoeba – Archerella flavum. Both are frequently present on slides designated for pollen analysis, prepared from Sphagnum peat. We analysed three profiles from three extensive ombrotrophic peatlands in northern Poland, in which the content of testate amoebae (TA) was examined and TA-inferred depth to the water table (DWT) was reconstructed. The new analysis of palynological samples regarding NPPs revealed that strong increases in HdV-10 content were mostly simultaneous to HdV-31A declines. However, the relations between both types were not statistically significant. The rapid increases in HdV-10, despite the fact that this type of conidiospores is related to drier habitats on peatlands, were tentatively interpreted as an indicator of rapid rises in the water table level which, in consequence, might have stimulated the production of these spores by fungi. In addition, a negative correlation between HdV-31A and Arcella discoides and positive one, but weaker, in case of HdV-10 (attributed by some authors to species Trichocladium opacum (Corda) S Hughes) and A. discoides show a link between mutual fluctuations of both NPPs and hydrological instabilities on peatland. The Bagno Kusowo bog, the westernmost peatland subjected to the study, displayed an intriguing agreement between the presence of peat sections with strong increases in HdV-10 and cold climate events affecting Europe. Our study reveals that counting even a limited number of NPP types during the standard pollen analysis of Sphagnum peat may support the interpretation of results, especially, in cases when the investigation lacks testate amoeba analysis. When the reconstruction of TA-inferred DWT is provided, it may introduce additional information about the patterns of hydrological dynamics.

Testate (shell-building) amoebae, such as the Arcellinida (Amoebozoa), are useful bioindicators for climate change. Though past work has relied on morphological analyses to characterize Arcellinida diversity, genetic analyses revealed the presence of multiple cryptic species underlying morphospecies. Here, we design and deploy Arcellinida-specific primers for the SSU-rDNA gene to assess the community composition on the molecular level in a pilot study of two samplings from a New England fen: (1) 36-cm horizontal transects and vertical cores; and (2) 26-m horizontal transects fractioned into four size classes (2-10, 10-35, 35-100, and 100-300 μm). Analyses of these data show the following: (1) a considerable genetic diversity within Arcellinida, much of which comes from morphospecies lacking sequences on GenBank; (2) communities characterized by DNA (i.e. active + quiescent) are distinct from those characterized by RNA (i.e. active, indicator of biomass); (3) active communities on the surface tend to be more similar to one another than to core communities, despite considerable heterogeneity; and (4) analyses of communities fractioned by size find some lineages (OTUs) that are abundant in disjunct size categories, suggesting the possibility of life-history stages. Together, these data demonstrate the potential of these primers to elucidate the diversity of Arcellinida communities in diverse habitats.

We evaluated the feasibility of using testate amoebae to infer the quantitative paleohydrology of ombrotrophic mires during their early stages (fen and fen-bog transition) of development. Two transfer functions, one derived from ombrotrophic and the other from minerotrophic mires, were applied to a peat core from an ombrotrophic mire in a taiga region of west Siberia. An ombrotrophic transfer function was applied to the bog stage of mire development. In contrast, ombrotrophic and minerotrophic transfer functions were applied independently to infer water table depth in the fen and fen-bog transition stages. Results of the two approaches for calculating water table depth during the fen and fen-bog transition stages differed by as much as 38 cm for the same peat sample. The main reason for this discrepancy is presence of testate amoeba taxa (e.g. Centropyxis aculeata, Cyclopyxis eurystoma, Cyclopyxis eurystoma v. parvula) in the peat that inhabit both modern ombrotrophic and minerotrophic mires, but differ substantially, in cases by > 20 cm, in terms of their water table depth optima in the ombrotrophic and minerotrophic mire calibration data sets. This difference in inferred water table depth also stems, to a lesser degree, from the fact that the ombrotrophic mire model does not include taxa that inhabited exclusively minerotrophic mires in the fen and fen-bog transition stages. Given these findings, we propose that different models be used for different stages of development, to reconstruct past water table depth in ombrotrophic mires. We recommend use of a model based solely on the ombrotrophic mire data set for the bog stage, and application of a second model based on the minerotrophic mire data set, for the fen and fen-bog transition stages. Application of an ombrotrophic model to the early stages of bog development can yield erroneous paleohydrological reconstructions.

Ancestral adaptations to tropical-like climates drive most multicellular biogeography and macroecology. Observational studies suggest that this niche conservatism could also be shaping unicellular biogeography and macroecology, although evidence is limited to Acidobacteria and testate amoebae. We tracked the phylogenetic signal of this niche conservatism in far related and functionally contrasted groups of common soil protists (Bacillariophyta, Cercomonadida, Ciliophora, Euglyphida and Kinetoplastida) along a humid but increasingly cold elevational gradient in Switzerland. Protist diversity decreased, and the size of the geographic ranges of taxa increased with elevation and associated decreasing temperature (climate), which is consistent with a macroecological pattern known as the Rapoport effect. Bacillariophyta exhibited phylogenetically overdispersed communities assembled by competitive exclusion of closely related taxa with shared (conserved) niches. By contrast, Cercomonadida, Ciliophora, Euglyphida and Kinetoplastida exhibited phylogenetically clustered communities assembled by habitat filtering, revealing the coexistence of closely related taxa with shared (conserved) adaptations to cope with the humid but temperate to cold climate of the study site. Phylobetadiversity revealed that soil protists exhibit a strong phylogenetic turnover among elevational sites, suggesting that most taxa have evolutionary constraints that prevent them from colonizing the colder and higher sites of the elevation gradient. Our results suggest that evolutionary constraints determine how soil protists colonize climates departing from warm and humid conditions. We posit that these evolutionary constraints are linked to an ancestral adaptation to tropical-like climates, which limits their survival in exceedingly cold sites. This niche conservatism possibly drives their biogeography and macroecology along latitudinal and altitudinal climatic gradients.

There is little knowledge about testate amoebae in lakes and their responses to volcanic eruptions. To address this knowledge gap, we studied the paleoecology of these protists in a sediment record from Laguna Verde, a lake located east of the southern Patagonian Ice Field, in Santa Cruz Province, Argentina. The lake is under the influence of volcanic eruptions from Lautaro Volcano, Chile, ~ 42 km WNW of Laguna Verde. We evaluated the response of 11 testate amoeba morphospecies in the lake to the last four Lautaro eruptions, using a 61-cm sediment core. Calcium (Ca), a major element of volcanic ash, was the most important variable explaining testate amoeba variability in the three zones determined by detretended correspondence analysis. We identified four declines in testate amoeba abundance and diversity associated with tephra deposition. Poisson regression analysis revealed that Difflugia immanata, D. bidens, and D. glans strain “glans” decrease after deposition of tephra layers. In contrast, Centropyxis constricta strain “constricta,” C. aculeata strain “aculeata” and Zivkovicia compressa respond positively to ash deposition. Our findings suggest a high resilience of testate amoebae to stochastic events such as volcanism because the same assemblage (D. immanata, D. bidens, and D. glans strain “glans”) inhabited the lake before and after the ashfalls. Nevertheless, several volcanic eruptions during the last ~ 300 years may have weakened this resilience and had a long-term effect on community diversity. Multivariate analysis showed that potassium (K) plays a significant role in shaping assemblage composition. Because of the low K content of the Lautaro tephra, we infer that higher potassium concentrations in sediments are not related with volcanic events, but rather, are associated with terrestrial input. Future studies, however, will be needed to identify the source of K in the sediment record and its relationship with testate amoebae assemblages. Our study demonstrates the potential for using lacustrine testate amoebae as environmental proxies, and illustrates the direct effects of volcanic ash deposition on their assemblage composition, diversity and distribution in southern Patagonia. Fil: Charqueño Celis, Norma Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Administración de Parques Nacionales. Parque Nacional "Nahuel Huapi"; Argentina Fil: Sigala, Itzel. Universidad Nacional Autónoma de México. Instituto de Geofísica; México Fil: Zolitschka, Bernd. Universitat Bremen. Institut Fuer Geographie; Alemania Fil: Pérez, Liseth. Technische Universitat Carolo Wilhelmina Zu Braunschweig. Iinstitut fur Geosysteme und Bioindikation; Alemania Fil: Mayr, Christoph. Institut Fur Geographie, Friedrich-alexander-universit; Alemania. Universitat Erlangen Nuremberg; Alemania. Ludwig Maximilians Universitat; Alemania Fil: Massaferro, Julieta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Administración de Parques Nacionales. Parque Nacional "Nahuel Huapi"; Argentina

The studies on the marine and freshwater testate amoebae of the Bulgarian Black Sea littoral and some related coastal brackish lakes are briefly reviewed. So far, a total of 184 species and subspecies of testate amoebae from 18 families and 45 genera from orders of Arcellinida and Euglyphida were published in national and international journals. The underground waters of the Bulgarian marine sand supralittoral are better studied than the related continental lakes. A total of about 45 species of marine interstitial testate amoebae are known, so far, and a big part of them were for the first time described from the Black Sea littoral. It’s interesting to note the presence in the marine underground waters of the Black Sea littoral of many freshwater testate amoebae also, considered by us as eurybionts. That is due of the low and variable salinity of the littoral Black Sea waters during the year. The presence of some psammobiotic testate amoebae as Psammonobiotus lineare and Corythionella georgiana in some related brackish lakes is also of ecological interest. The general conclusion of the present synthesis is that the testate amoebae fauna of the Bulgarian Black Sea coast and the related with it many brackish and freshwater littoral lakes is few known yet and need more active researches.

The first data on the species diversity of testate amoebae of the Coco River in the provinces of Quang Nam and Da Nang (Vietnam) are presented. A total of 55 species and subspecies of testate amoebae belonging to nine genera and six families have been identified in 28 samples. Species diversity of testate amoebae in plankton is higher than in benthic samples. Centropyxis aculeata (64.3%), Netzelia wailesi (39.3%), Difflugia acuminata (32.1%), Arcella discoides scutelliformis (28.6%), and Lesquereusia modesta (28.6%) are characterized by the highest frequency of occurrence. Difflugia (25), Arcella (12), Centropyxis (5), and Netzelia (4) are the most species-rich genera. The species accumulation curve based on the entire dataset is unsaturated and is described by the equation y = 12.56N0.46. The average species richness of testate amoebae per sample in plankton (13.0 ± 3.1) is statistically higher than in benthic samples (1.8 ± 1.5) (p < 0.001). The result of the redundancy analysis shows that the studied hydrochemical water parameters (temperature, pH, dissolved oxygen, electrical conductivity, and salinity) explain only 31.6% of the variation of testate amoeba diversity; the first and second axes explain 11 and 10.2% of this variation, respectively.

Testate amoebae are a group of free-living heterotrophic protists that have an organic shell or test and play a very good role as bioindicators in the ecological monitoring of environment. Inspite of the importance the percentage contribution of free living protozoans recorded from the Himalayan landscape is only about 12% of the total free living protozoans of India. This portrays a meagre diversity of species from such a highly diversified ecosystem of Himalaya and the true diversity may be far above the recorded number of species. In this study it is herewith reporting two species of testate amoebae viz., Assulina quadratum Van Oye, 1958 and Cyclopyxis leidy Couteaux et Chardez, 1981 for the first time from India from Sangla Valley, Himachal Pradesh. Key words: Assulina quadratum, Cyclopyxis leidy, bioindicator protists, moss-dwelling testate amoebae, soil protists, new biogeographic records, Sangla Valley, Himachal Pradesh, India.

Microbial communities have not been studied using molecular approaches at high elevations on the African continent. Here we describe the diversity of microbial communities from ice and periglacial soils from near the summit of Mt. Kilimanjaro by using both Illumina and Sanger sequencing of 16S and 18S rRNA genes. Ice and periglacial soils contain unexpectedly diverse and rich assemblages of Bacteria and Eukarya indicating that there may be high rates of dispersal to the top of this tropical mountain and/or that the habitat is more conducive to microbial life than was previously thought. Most bacterial OTUs are cosmopolitan and an analysis of isolation by geographic distance patterns of the genus Polaromonas emphasized the importance of global Aeolian transport in the assembly of bacterial communities on Kilimanjaro. The eukaryotic communities were less diverse than the bacterial communities and showed more evidence of dispersal limitations and apparent endemism. Cercozoa dominated the 18S communities, including a high abundance of testate amoebae and a high diversity of endemic OTUs within the Vampyrellida. These results argue for more intense study of this unique high-elevation “island of the cryosphere” before the glaciers of Kilimanjaro disappear forever.

Testate amoebae are important components of benthic communities in freshwater lakes, where they play an essential role in decomposer food webs. They are used widely in paleoecological investigations because of their high taxonomic diversity, well-defined ecological preferences and decay-resistant tests. Studies of testate amoeba assemblages in lake surface sediments are necessary to better understand lake ecosystem function and improve the use of these organisms as bio-indicators in paleoecology. This study explored the use of testate amoebae as proxies for inferring past water level in freshwater lakes, and expanded upon the limited body of research into lake testate amoebae in Russia. Our results indicate that species composition of testate amoeba assemblages in the lakes was typical for such biotopes, with most of the species belonging to the genera Difflugia, Centropyxis, Arcella and Euglypha. Analysis of variation of testate amoebae along a water-depth gradient showed that three assemblage types could be distinguished: shallow-water (0–4.5 m), intermediate-water-depth (4.5–20.5) and deep-water (20.5–33 m). Deep-water assemblages did not contain any unique taxa and were dominated by eurybiotic and planktonic species. Species diversity was highest in the intermediate-water-depth assemblages and lowest in deep-water ones. Although variations in testate amoeba assemblages across water depth in freshwater lakes are complex and context-dependent, there are clear patterns in species composition and diversity, which can be used to infer past lake water levels. Future studies on the effect of water depth on testate amoeba assemblages in diverse types of freshwater lakes should increase the utility of the method.

Difflugia are testate amoebae that use particulate inorganic matter to build a protective shell (generally called a test or theca). Difflugia globulosa were grown both in culture containing only naturally occurring theca-building materials and under conditions where synthetic particles were present also. The presence of monodisperse Stober silica microspheres of 1, 3, and 6 μm in diameter or 4 μm polystyrene spheres dramatically increased the rate of Difflugia growth, and foreign microspheres became the overwhelmingly dominant construction material. Optical and electron microscopy of the 6 μm particle studies revealed that Difflugia construct spherical vase-shaped thecae with strikingly reproducible composition, morphology, and size. Time-lapse photography revealed construction techniques and masonry skills as Difflugia herded particles together, trapped them using phagocytosis, and applied the particles with biocement from inside the developing theca. The reported observations identify taxonomy complications, biomicrofabrication possibilities, and a discrete environmental impact of synthetic particle pollutants.

Compared to boreal or Mediterranean biomes, the influence of fire on peatlands in Central Europe is not well studied. We aim to provide first analysis of statistically significant charcoal-inferred fire events from a peatland from central European lowlands, spanning the period of the last 650 years, and define peatland vegetation and microbial trait-related responses to local fire events. Here, we reconstructed regional and local fire activity from Bagno Kusowo bog (Poland) using high-resolution microscopic charcoal and macroscopic charcoal and its morphotypes, inferring past fire regimes using numeric analyses. We compared fire data with extra-local (pollen) and local (plant macrofossils, testate amoebae (TA) and their trait composition) proxies. Our data show that within the chronological uncertainties, regional fires recorded in the peat core coincide with historically-documented fires. Macroscopic charcoal analysis suggests 3–8 local fire events, while fire frequency varied between 0 and 2 events/1000 years. Wood charcoal was dominant throughout the profile, pointing to forest fires in close proximity to the peatland. Local fire activity was the most intensive in the 17th century, when the water table was at its lowest. The abundance of Sphagnum spp. declined, whereas vascular plants, mixotrophs and TA with proteinaceous shells were significantly positively correlated to fire. Xenosomes were significantly negatively correlated to fires, and they responded to water table lowering. We show that the peatlands’ vegetation recovered from low-intensity and short-lasting disturbances and, to some extent, maintained “pristine” local vegetation cover with Sphagnum as the dominant taxon. TA traits common before disturbances, mainly mixotrophs and TA with proteinaceous shells, temporarily re-appeared after fire. We conclude that TA communities in peatlands are good bioindicators of disturbances.

Karst freshwater caves are subterranean habitats characterized by the constant absence of light and relatively small variations of temperature and air humidity. They are mostly food deprived environments, with the exception if large bat colonies are present or if they are intensively supplied with organic matter by sinking rivers. Even though these habitats are often described as harsh, they have enabled the evolution of highly specialized and often endemic animals. The cave eukaryotic micro-organisms, on the other hand, are scarcely researched. The results of research of testate amoebae in the caves of the Dinaric arc detected 23 species, 12 of which were first found in caves. Also, a description of Centropyxis bipilata sp. nov. is presented. This species is clearly distinguished from other described species based on shell size, the presence of two struts and the usually dark ring around the aperture. Testate amoebae were registered on aquatic and terrestrial cave sediments and transitional habitats (like hygropetric and wet walls). The most frequent species within the samples were: Trinema lineare, Cryptodifflugia oviformis and Centropyxis bipilata sp. nov. Maximum diversity of testate amoebae was registered in Ponor Kovači with twenty species. In 24.4 % of the investigated samples microphototrophs were found, implying good surface-subsurface connectivity that could also affect testate amoebae diversity. This research showed that caves are underestimated habitats that can provide us with new data about the testate amoebae biogeography and diversity.

Although it is well established that moisture availability in south-eastern Australia has been decreasing through time recently, the driver(s) of this trend are contentious, and our understanding of any drivers is limited by a relatively short historic record. Testate amoebae have been widely used to reconstruct peatland hydrology in the Northern Hemisphere, but in the Southern Hemisphere research is still needed to assess their proficiency as a palaeohydrological proxy and to develop robust transfer functions. Here we examine the ecology of testate amoebae in several high altitude mires in south-eastern Australia and present the first transfer function for the continent. Euglypha tuberculata type, Centropyxis platystoma type and Assulina muscorum were the most common taxa in our modern samples. Water-table depth was the primary environmental variable determining testate amoebae assemblages and therefore transfer functions were developed for this ecological factor. We found that the performance of various all-species and species-pruned transfer functions were statistically robust, with R2 values of around 0.8 and Root Mean Squared Error of Prediction (RMSEP) values of about 7 cm. All cross-validation methods (leave-one-out RMSEP, cluster-bootstrap RMSEP, segment-wise RMSEP and leave-one-site-out RMSEP from all-species and species-pruned transfer functions) suggested that the Modern Analogue Technique (MAT) was the best performing transfer function, with negligible bias evident from un-even sampling and spatial autocorrelation. We also used a new approach to evaluate the importance of taxa and the performance of our transfer functions using species-pruned methods. Our results suggest that the all-species MAT, with an RMSEP of 5.73 and R2 of 0.86, provides the best reconstruction of water-table depth across our sites in south-eastern Australia.

Several processes contributing to coastal relative sea-level (RSL) change in the North Atlantic Ocean are observed and/or predicted to have distinctive spatial expressions that vary by latitude. To expand the latitudinal range of RSL records spanning the past ∼3000 years and the likelihood of recognizing the characteristic fingerprints of these processes, we reconstructed RSL at two sites (Big River and Placentia) in Newfoundland from salt-marsh sediment. Bayesian transfer functions established the height of former sea level from preserved assemblages of foraminifera and testate amoebae. Age-depth models constrained by radiocarbon dates and chronohorizons estimated the timing of sediment deposition. During the past ∼3000 years, RSL rose by ∼3.0 m at Big River and by ∼1.5 m at Placentia. A locally calibrated geotechnical model showed that post-depositional lowering through sediment compaction was minimal. To isolate and quantify contributions to RSL from global, regional linear, regional non-linear, and local-scale processes, we decomposed the new reconstructions (and those in an expanded, global database) using a spatio-temporal statistical model. The global component confirms that 20th century sea-level rise occurred at the fastest, century-scale rate in over 3000 years (P > 0.999). Distinguishing the contributions from local and regional non-linear processes is made challenging by a sparse network of reconstructions. However, only a small contribution from local-scale processes is necessary to reconcile RSL reconstructions and modeled RSL trends. We identified three latitudinally-organized groups of sites that share coherent regional non-linear trends and indicate that dynamic redistribution of ocean mass by currents and/or winds was likely an important driver of sea-level change in the North Atlantic Ocean during the past ∼3000 years.

The aim of the study is to describe the testate amoebae fauna in seven reservoirs in the Northeastern Bulgaria and to investigate the relationship of taxonomic diversity and abundance of these organisms to the some characteristics of the reservoirs. A total of 52 species, varieties and forms belonging to 15 genera were identified in the benthal of the coastal zone. There are significant differences in species richness and abundance between the testacea of different reservoirs. Number of taxa was significantly higher in the Beli Lom (29 species and 12 genera) and Loznitsa (22 species and 13 genera). Most of the reservoirs - Kara Michal, Bogdantsi, Isperih, Lipnik and Brestovene have extremely poor fauna compared to other similar reservoirs. This is confirmed by the low values of the Shannon-Weaver diversity index, which varied between 1.04 and 2.396, as well as by the other indices used to assess the environmental conditions in the reservoirs. The data of the regression analysis showed that a relation between age, surface area and water volume of the reservoirs and the species richness and abundance of testacea is not established.

Southern Spain is currently under threat of desertification as a consequence of global climate change, which pressures on fragile ecosystems such as caves. The organisms living in these extremely stable environments are particularly sensitive and prone to extinction, therefore they can be used as bioindicators for climate change. Cyanobacterial mats form peculiar and vulnerable micro-ecosystems at the entrance of caves and house a diversity of protists. Amongst them, Arcellinida testate amoebae have been traditionally used as bioindicators for environmental quality, notably because their narrow ecological tolerance and their key ecological position as top predators of the microbial foodwebs. We report here two new species of Arcellinida found in the cyanobacterial mats of cave Hundidero, in Sierra de Grazalema, Malaga province, whose traits suggest a narrow tolerance for changes in humidity. We provide a formal description for Difflugia alhadiqa sp. nov. and Heleopera baetica sp. nov. based on morphometrics and 18S rRNA gene data, and propose using the presence of these species to indicate the good health of the cyanobacterial mats, like miner’s canaries for local climate.

To distinguish human-caused from naturally-caused fire regimes, palaeoecological records must demonstrate that observed changes in vegetation and fire are in response to changes in human activity rather than driven by natural climate-fire relationships. Here, we use a high-resolution multi-proxy approach (testate amoebae derived depth to water table (DWT), macro- and micro-charcoal, charcoal morphologies, pollen, non-pollen palynomorphs, plant macrofossils, and XRF) from Pékna, a mid-elevation peat bog situated near Lipno Reservoir - an area rich in human land use - to investigate human-driven vs. naturally-driven fire regimes in the Šumava Mountains. Our results span the entire Holocene and illustrate that humans have been consistently modifying the landscape since 5,500 cal yr BP. Specifically, during the mid-Holocene (7,000 – 4,000 cal yr BP) when water table was at its highest at Pékna, relatively frequent, low-severity fires occurred and was accompanied by the prolonged presence of coprophilous fungi, secondary human indicators and an opening of the forest, suggesting human activities. Human land use intensified ~1,500 cal yr BP as indicated by increases in primary human indicator species, an increase in early successional tree species (Pinus and Betula) indicating an opening of the forest canopy, and the development of regional mining is suggested by a marked increase in the concentration of lead (Pb). While water table depths decreased indicating drier conditions ~1,500 cal yr BP, local fires persisted, burning at low severities as indicated by the continued presence of charred herb macrofossils. The most intensive land use occurred in the last 500 years with the highest abundance of primary and secondary human indicator species, and coprophilious fungi. Locally, marked increases in the concentration of both redox-sensitive elements such as iron (Fe), calcium (Ca), sulphur (S), and chlorine (Cl), and detrital elements such as potassium (K), aluminum (Al) and Titanium (Ti) indicate major changes in the depositional environment over the last 500 years, possibly due to peat draining. However, this time period witnessed decreased biomass burning as a result of a more open landscape and less fuels to burn. These results contribute to a growing body of literature illustrating the importance of prehistoric impact in the mid-mountains of Central Europe.

The new testate amoeba species Meisterfeldia bitsevi is described from the linden-tree trunk hollow in the urban park in Moscow (Russia). New species is characterized by elongated ovoid bilaterally symmetrical shell, which is laterally not compressed. The shell is composed of proteinaceous material without mineral particles. Almost circular subterminal aperture is placed on ventral side. The key to the species of the genus Meisterfeldia is developed.

Testate amoebae are one of the most studied groups of microorganisms in Sphagnum peatland ecosystems and, therefore, one of the most reliable bioindicators of their ecological status. Peatland ecosystems are supported by a delicate biogeochemical balance that leads to the formation of peat, one of the main sinks of C, as a result of soil–atmosphere interaction, but currently they are one of the most threatened wetland types at their southern distribution limit. In the European continent, where climatic conditions limit peat formation, they have endured significant anthropic pressure for centuries, and the risk of loss of biodiversity linked to these ecosystems is critical. In addition, peatlands are poorly known ecosystems in the Iberian Peninsula compared with other wetlands, therefore, we have studied the chemical parameters of water and the diversity patterns of testate amoebae in the western Iberian Peninsula to better understand the current status of these ecosystems. The analysis of testate amoeba communities showed an inverse relationship between the diversity and conservation status of these peatlands, both in relation to chemical parameters (i.e., pH, electrical conductivity, phosphates) and to the proportion of anthropized area, with a marked geographical pattern in the degree of anthropogenic disturbance.

Testate amoebae are a diverse group of shelled protists frequently used as model organisms in microbial biogeography. Relatively few species have been reported for the Southern Hemisphere, however, it remains unclear whether this lower diversity is real or an artifact of under-sampling or misidentifications, which would reduce their potential to address macroecological questions. We evaluated testate amoebae diversity from the full range of habitats occurring within two Tierra del Fuego peatlands and compared it with the reported diversity for the area and from the Northern Hemisphere peatlands. We recorded 87 species, of which 69 are new for the region and 45 of them probably new to science and likely to have restricted geographical distributions. Combined with previous studies, the total diversity of testate amoebae only from Tierra del Fuego peatlands now reaches 119, as compared with 183 reported from all Northern Hemisphere peatlands. Our results demonstrate that the number of Gondwanian and Neotropical endemic testate amoeba may be substantially higher than currently known. Previous reports of Holarctic taxa in Tierra del Fuego may result from forcing the identification of morphotypes to the descriptions in the most common literature (force-fitting) South American species into species common in literature from other regions.

Understanding the extent of human activities leading to an influx of chemical pollutants that cause substantial environmental transformations is the focus of much ongoing research. In this study, we present a multi-proxy record based on a sediment core from a large subtropical reservoir (Xinfengjiang Reservoir) in south China with an emphasis on the changes in testate amoebae community, in combination with sedimentological (radioactivity, physicochemistry, nutrient and organochlorine pesticides) and climatological (air temperature and precipitation) data over the last three decades. Twenty-seven testate amoebae species belonging to seven genera (Arcella, Centropyxis, Cyclopyxis, Difflugia, Netzelia, Euglypha and Pseudodifflugia) were observed. Species richness, abundance and biomass of testate amoebae were in ranges of 18-26 species, 616-825 ind. ml-1 and 9.0-19.4 μg C ml-1, respectively. Two development stages of the reservoir, dated to 1978-1993 (stage 1) and 1993-2006 (stage 2), were distinguished based on testate amoebae communities. Stage 1 was characterized by elevated dry bulk density, carbon-to‑nitrogen ratio and p,p'-DDE in the sediment core and an impact of nitrogen and sulfur deficiency on testate amoebae. Stage 2 was marked by a decrease of dry bulk density, elevated concentrations of aluminum, iron and carbon, low carbon-to‑nitrogen ratio and organochlorine pesticides, fluctuations in rainfall on shorter and yearly timescales, and a stronger influence of the organochlorine pesticides on testate amoebae. Testate amoebae community change and the identified two-stage development were consistent with atmospheric deposition of organochlorine pesticides from anthropogenic sources inside and outside the reservoir watershed, nutrient influx and sediment physicochemistry. The testate amoebae community dynamics and a strong community-environment relationship in stage 2 were linked with non-random patterns in the biotic neighborhoods of species (deterministic processes). The results suggest a stronger impact of anthropogenic disturbance than natural environmental change on testate amoebae community variation of Xinfengjiang Reservoir over time.

The majority of Euglyphida species are characterised by shells with imbricated silica scales. Environmental surveys indicate a large unexplored diversity and recent efforts hinted at a certain diversity of yet undescribed, inconspicuous, scale-lacking Euglyphida. Here we describe Phaeobola aeris gen. nov., sp. nov. that shows a variety of morphological characters typical for the Euglyphida but lacks silica scales - instead, this species bears an agglutinated test. Neither its morphology nor phylogenetic placement allows its assignment to any currently described family. We erected the yet monospecific genus Phaeobola gen. nov., which with yet available data remains Eugylphida incertae sedis.

We review the potential for applying traits-based approaches to freshwater testate amoeba, a diverse protist group that are abundant in lakes and are valuable ecological indicators. We investigated the efficacy of geometric morphometric analysis to define Arcellinida test size and shape indices that could summarize freshwater testate amoeba community dynamics along a temporal gradient of eutrophication in Loch Leven, Scotland (United Kingdom). A cluster analysis of test size and shape indices yielded three clusters, each dominated by a single shape: elongate, spherical and ovoid. When plotted stratigraphically, we observed increases in spherical tests, decreases in elongate tests and shrinking of test size coeval with eutrophication in Loch Leven. Decreases in the elongate cluster may reflect benthic conditions with reduced oxygen levels, while increases in the spherical cluster are likely associated with an expanding macrophyte community that promoted pelagic and epibiotic life habits. Shrinking of test size may be a stress response to eutrophication and/or warming temperatures. Tracking community dynamics using test size and shape indices was found to be as effective as using species-based approaches to summarize key palaeolimnological changes, with the added benefits of being free from taxonomic bias and error. The approach thus shows significant potential for future studies of aquatic community change in nutrient impacted lakes.

New species, Frenopyxis stierlitzi, is described from tree hollows in the urban parks in Moscow (Russia) and Potsdam (Germany). The species belongs to the new genus of the family Centropyxidae and characterized by unique character, i.e. an internal thick organic lip surrounding an aperture and continuing in a bridle, which connects an aperture with the internal side of a shell wall and broaden in the place of connection of a bridle and a shell wall. The systematics of the family Centropyxidae is discussed and the importance of the structures, which divide inner shell volume into compartments, is underlined.

The reports of testate amoebae species in Colombia are limited to a few studies in lentic and peat bog systems; however, the diversity in lotic systems has been poorly investigated. Zooplankton sampling was performed in lotic environments of the Piedemonte Llanero in Colombia. Ten individuals of the species Arcella gandalfi were identified to document the first record of A. gandalfi from the Piedemonte Llanero in Colombia, expanding its distribution from Brazil to Colombia. This finding corroborates the status of A. gandalfi as a flagship species from the South America continent.

Northern peatlands, which are highly heterogeneous ecosystems, are a globally important carbon (C) store. Understanding the drivers and predicting the future trajectory of the peatland C store requires upscaling from cores and sites to regions and continents, alongside a detailed understanding of the mechanisms governing their C sequestration. Studies incorporating replication are therefore important to quantify how peatland heterogeneity may affect upscaling from local-scale dynamics to models. In addition, we need to better understand the processes driving observed variability, but the interplay between plants, microbes and C cycling in peatlands remains poorly understood. One approach to address both issues is to examine replicated microbiological functional traits within a multi-proxy framework to provide an ecosystem-level perspective on ecological and biogeochemical processes. Peatland testate amoebae are a functionally important group of protists that are well suited to such an approach. Analysing testate amoeba functional traits provides an opportunity to examine processes that may affect key peatland ecosystem services, such as C sequestration. Here, we compared four key testate amoeba functional traits (mixotrophy, biovolume, aperture size and aperture position) to C accumulation, hydrological and vegetation changes in 12 post-Little Ice Age peat records. Samples were collected from high-boreal and low-subarctic regions in northwestern Quebec, Canada in an experimental design that includes internal and external replication at both site and regional scales. Our results showed that correspondence between C accumulation, hydrology and testate amoeba functional traits varied, but recent changes in mixotrophy and aperture size, which may affect peatland C sequestration potential and microbial food web structure, respectively, showed tentative links to recent C accumulation increases. Vegetation, especiallySphagnumabundance was important in promoting mixotrophy and small aperture size in testate amoeba communities. Future impacts of climate change on peatland vegetation will further influence the functional role of testate amoebae on C sequestration through changing mixotrophic testate amoeba abundance.

Background. Testate amoebae are an important component of marsh, freshwater and soil ecosystems. Many species have clear environmental preferences, making them useful bioindicators. Currently, more and more investigations are devoted to the study of the structural organization of the testate amoebae communities in different types of biotopes and to the identification of the main causes of changes in the species composition and abundance. However, issues related to the identification of mechanisms that ensure the coexistence of closely related species still remain without due attention. Materials and methods. The study was conducted on the aapa moor, located in the northern subzone of the taiga in the vicinity of the Pertsov White Sea Biological Station, Moscow State University (WSBS MSU). We studied the horizontal distribution of testate amoebae on a macro- (40 × 150 m), meso- (10 × 10 cm), microscale (3 × 3 cm), and vertical distribution in the deep of the sphagnum. Results. In 86 samples revealed 11 574 tests belonging to 109 species and subspecies from 33 genera. Representatives of the order Arcellinida make up a significant share in the testate amoebae community (from 36 to 63 % of the total abundance in different samples). Testate amoebae are characterized by rare joint occurrence in samples throughout the whole aapa moor. The average index of similarity of distributions of the most abundant species (more than 5 % of the total abundance) is 0,2 (Brey – Curtis index). The distribution of the amoebae in the area of 100 cm2 was significantly more homogeneous (the average Brey – Curtis index is 0,78). The distribution of amoebae on a microscale (10 cm2) was very heterogeneous: some species (Hyalosphenia papilio, Heleopera rosea and Heleopera sphagni) show high similarity indices of 0,7–0,78, others (Centropyxis elongata) are characterized by a low level of overlap (average 0,26). The average index of similarity in a microscale is 0,47. The vertical divergence of species is very weak (the average Brey – Curtis similarity index is 0,75). Conclusions. The testate amoebae community is structured mainly due to the differentiation of ecological niches of species on the scale of the whole aapa-mire, as well as individual groups diverge on a microscale. The role of horizontal distribution at the mesoscale and vertical distribution in the divergence of spatial components of ecological niches is significantly lower.

Amoeboid protists are extremely abundant and diverse in natural systems where they often play outstanding ecological roles. They can be found in almost all major eukaryotic divisions, and genomic approaches are bringing major changes in our perception of their deep evolutionary relationships. At fine taxonomic levels, the generalization of barcoding is revealing a considerable and unsuspected specific diversity that can be appreciated with careful morphometric analyses based on light and electron microscopic observations. We provide examples on the difficulties and advances in amoeboid protists systematics in a selection of groups that were presented at the VIIIth ECOP/ISOP meeting in Rome, 2019. We conclude that, in all studied groups, important taxonomical rearrangements will certainly take place in the next few years, and systematics must be adapted to incorporate these changes. Notably, nomenclature should be flexible enough to integrate many new high level taxa, and a unified policy must be adopted to species description and to the establishment of types.

Studies on testate amoeba species distribution at small scales (i.e., single peatland sites) are rare and mostly focus on bogs or mineral-poor Sphagnum fens, leaving spatial patterns within mineral-rich fens completely unexplored. In this study, two mineral-rich fen sites of contrasting groundwater chemistry and moss layer composition were selected for the analysis of testate amoeba compositional variance within a single site. At each study site, samples from 20 randomly chosen moss-dominated plots were collected with several environmental variables being measured at each sampling spot. We also distinguished between empty shells and living individuals to evaluate the effect of empty shell inclusion on recorded species distribution. At the heterogeneous-rich Sphagnum-fen, a clear composition turnover in testate amoebae between Sphagnum-dominated and brown moss-dominated samples was closely related to water pH, temperature and redox potential. We also found notable species composition variance within the homogeneous calcareous fen, yet it was not as high as for the former site and the likely drivers of community assembly remained unidentified. The exclusion of empty shells provided more accurate data on species distribution as well as their relationship with some environmental variables, particularly moisture. Small-scale variability in species composition of communities seems to be a worthwhile aspect in testate amoeba research and should be considered in future sampling strategies along with a possible empty shell bias for more precise understanding of testate amoeba ecology and paleoecology.

A total of 31 surface sediment samples from 16 coastal inlets in five sounds of western Vancouver Island were investigated for dinoflagellate cysts and other palynomorphs. Well-preserved and abundant dinoflagellate cysts were recovered, including a total of 32 cyst taxa belonging to four families. Total dinoflagellate cyst concentrations vary two orders of magnitude, with concentrations between 2267 and 918,584 cysts g−1. The highest values were observed in samples from Tofino Inlet. Southern sites are characterized by cysts of autotrophic dinoflagellates, mainly Operculodinium centrocarpum sensu Wall & Dale 1966. Other abundant cysts of autotrophic dinoflagellates are Spiniferites spp. and cysts of Pentapharsodinium dalei. In general, other inlets in Quatsino, Kyuquot-Nootka and Clayoquot Sounds have lower total concentrations but have more cysts of heterotrophic dinoflagellates, mainly Round brown cysts, Brigantedinium spp., and Spiny brown cysts. Neroutsos Inlet is characterized by high concentrations of Arcellacean testate amoebae. Within inlets, cyst concentrations and assemblages vary. Near the heads of the inlets, concentrations are generally lower and assemblages are dominated by cysts of autotrophic dinoflagellates, mostly O. centrocarpum sensu Wall & Dale 1966. Concentrations of cysts produced by heterotrophic dinoflagellates and their proportions in the assemblages generally increase from the head to the mouth of each inlet. Measured sedimentary biogenic silica abundances (%Opal) have consistently higher values in Clayoquot Sound and lower values in Quatsino Sound. Within individual inlets, biogenic silica generally increases in the head to mouth direction. The trend in heterotrophic cyst abundances is similar. Correlations between total organic carbon (TOC), total nitrogen (TN) and terrestrial palynomorph concentrations in the sediments indicate that the organic material at sites near inlet heads are mainly derived from terrestrial input. A significant negative correlation between biogenic silica and TOC/TN ratio was observed in the dataset, but not between the total heterotrophic cyst concentrations and relative abundances of biogenic silica. Statistical analyses (PCA, RDA) indicate that the assemblages of dinoflagellate cysts and other palynomorphs, their spatial distributions, and sedimentary geochemical measurements are related to the regional environmental setting (e.g., latitudinal trends in weather, primary productivity, and upwelling) and local characteristics of the inlets (e.g., site location relative to freshwater input, inlet morphology and bathymetry, as well as possible anthropogenic influences). Process length variation of O. centrocarpum sensu Wall & Dale 1966 was measured and it is comparable to previous measurements in similar environmental settings, allowing seawater densities to be inferred. Cysts of Alexandrium spp. were found in most of the samples, with the highest abundance in the inlet heads of Kyuquot and Quatsino Sounds.

Two of the main goals of forensic science are (1) to estimate the time since death, or post mortem interval (PMI) and (2) to find the site where a dead body was buried. Soil testate amoebae and diatoms may be useful indicators for these goals. However, the structure and patchiness of the habitat appears to be a main driver for the amoeba and diatom soil communities (e.g., individual density). In case the soil substrate is very dry and nutrient-poor (as in our study), the influence of a dead body on the soil microfaunal community may be superimposed by natural environmental heterogeneity, especially soil moisture content. Further studies are necessary to clarify if protist abundance data are helpful for forensic investigations.

Sphagnum riparium (Angstrom) is a rare constituent of modern peatland plant communities and is also very rarely found as a subfossil in peat archives. We present new data on the occurrence of Sphagnum riparium macrofossils in three Northern Hemisphere peatlands from Yellowknife (NW Canada), Abisko (N Sweden), and the Northern Ural Mountains (NW Russia). Sphagnum riparium macrofossils were present in transitional phases between rich fen and oligotrophic bog. Sphagnum riparium was a dominant species in the three sites and was found in combination with Sphagnum angustifolium, Drepanocladus sp., and vascular plants including Andromeda polifolia, Chamedaphne calyculata and Oxycoccus palustris. Testate amoebae indicate that the species occurred in wet to moderately wet conditions (water-table depth inferred from a testate amoeba transfer function model ranged between 25 and 0 cm under the peatland surface). The wet-indicator taxa Archerella flavum and Hyalosphenia papilio dominated the testate amoeba communities in peat horizons containing Sphagnum riparium. The presence of Sphagnum riparium macrofossils in peat profiles in the Northern Hemisphere can be interpreted as an indication of wet minerotrophic conditions, often corresponding to a rise in water-level and establishment of a wet habitat. Sphagnum riparium is a transient species in these peatlands and is replaced by communities dominated by more acidophilic species such as Sphagnum angustifolium, Sphagnum russowii, and Sphagnum fuscum. Our data show that although Sphagnum riparium is a transient peat-forming species, it is widespread in sub-arctic and boreal environments. The subfossil occurrence of Sphagnum riparium in the Northern Hemisphere may indicate that its range has increased during the Late Holocene. The conservation of Sphagnum riparium in peatlands depends on the existence of relatively short-lived transitional communities which potentially can be artificially created.