Fine-Scale Horizontal and Vertical Micro-distribution Patterns of Testate Amoebae Along a Narrow Fen/Bog Gradient

The ecology of peatland testate amoebae is well studied along broad gradient from very wet (pool) to dry (hummock) micro-sites where testate amoebae are often found to respond primarily to the depth to water table (DWT). Much less is known on their responses to finer-scale gradients, and nothing is known of their possible response to phenolic compounds, which play a key role in carbon storage in peatlands. We studied the vertical (0–3, 3–6, and 6–9 cm sampling depths) micro-distribution patterns of testate amoebae in the same microhabitat (Sphagnum fallax lawn) along a narrow ecological gradient between a poor fen with an almost flat and homogeneous Sphagnum carpet (fen) and a “young bog” (bog) with more marked micro-topography and mosaic of poor fen and bog vegetation. We analyzed the relationships between the testate amoeba data and three sets of variables (1) “chemical” (pH, Eh potential, and conductivity), (2) “physical” (water temperature, altitude, i.e., Sphagnum mat micro-topography, and DWT), and (3) phenolic compounds in/from Sphagnum (water-soluble and primarily bound phenolics) as well as the habitat (fen/bog) and the sampling depth. Testate amoeba Shannon H′ diversity, equitability J of communities, and total density peaked in lower parts of Sphagnum, but the patterns differed between the fen and bog micro-sites. Redundancy analyses revealed that testate amoeba communities differed significantly in relation to Eh, conductivity, water temperature, altitude, water-soluble phenolics, habitat, and sampling depth, but not to DWT, pH, or primarily bound phenolics. The sensitivity of testate amoebae to weak environmental gradients makes them particularly good integrators of micro-environmental variations and has implications for their use in paleoecology and environmental monitoring. The correlation between testate amoeba communities and the concentration of water-soluble phenolic suggests direct (e.g., physiological) and/or indirect (e.g., through impact on prey organisms) effects on testate amoebae, which requires further research.     

Comparative ecology of vascular plant,bryophyte and testate amoeba communities in four Sphagnum peatlands along an altitudinal gradient in Switzerland

Monitoring tools are needed to assess changes in peatland biotic communities and ecosystem functions in response to on-going climate and other environmental changes. Although the responses of soil organisms and plants to ecological gradients and perturbations do not always correlate, peatland monitoring is mainly based on vegetation surveys. Testate amoebae, a group of protists, are important contributors to carbon and nitrogen cycling in organic soils and are useful bioindicators in peatland ecology and paleoecology. There is however little comparative data on the value of testate amoebae, vascular plants and bryophytes as bioindicators of micro-environmental gradients in peatlands.We compared the relationships of testate amoebae, bryophytes, and vascular plants with soil temperature, water table depth, micro-habitats and the carbon and nitrogen content of Sphagnum mosses in four peatlands along a 1300 m altitudinal gradient in Switzerland. We used the full diversity of vascular plants and bryophyte but only a selection of ten easily identifiable testate amoeba morpho-taxa (i.e. species or species-complexes).Indirect and direct gradient ordinations, multiple factor analysis (MFA) and transfer function models for inferring water table depth showed that a selection of ten testate amoeba taxa are more powerful (% variance explained in RDA) and accurate (discrimination among habitats) indicators of local conditions (micro-habitat type, water table depth and Sphagnum C/N ratio) than the vegetation (vascular plants and bryophytes either individually or combined and considering the full diversity).Our study showed that a limited list of ten easily identifiable testate amoeba taxa have higher bioindication value than the full bryophytes and vascular plants. Furthermore, testate amoebae can be analyzed on samples collected at any season (accessibility allowing and if precise sampling sites are well marked) – a clear advantage for biomonitoring and can be used to infer past changes from the peat record at the same taxonomic resolution. This simple approach could therefore be very useful for biomonitoring of peatlands.     

Loss of testate amoeba functional diversity with increasing frost intensity across a continental gradient reduces microbial activity in peatlands

Soil microbial communities significantly contribute to global fluxes of nutrients and carbon. Their response to climate change, including winter warming, is expected to modify these processes through direct effects on microbial functions due to osmotic stress, and changing temperature regimes. Using four European peatlands reflecting different frequencies of frost events, we show that peatland testate amoeba communities diverge among sites with different winter climates, and that this is reflected through contrasting functions. We found that exposure to harder soil frost promoted species β-diversity (species turnover) thus shifting the community composition of testate amoebae. In particular, we found that harder soil frost, and lower water-soluble phenolic compounds, induced functional turnover through the decrease of large species (−68%, >80 μm) and the increase of small-bodied mixotrophic species (i.e. Archerella flavum; +79%). These results suggest that increased exposure to soil frost could be highly limiting for large species while smaller species are more resistant. Furthermore, we found that β-glucosidase enzymatic activity, in addition to soil temperature, strongly depended of the functional diversity of testate amoebae (R² = 0.95, ANOVA). Changing winter conditions can therefore strongly impact peatland decomposition process, though it remains unclear if these changes are carried-over to the growing season.     

Seasonal Influences on the Ecology of Testate Amoebae (Protozoa) in a Small <Emphasis Type="Italic">Sphagnum</Emphasis> peatland in Southern Ontario,Canada

Testate amoebae (Protozoa) were studied in spring, summer, and fall from the same microhabitats in a small Sphagnum-dominated peatland in southern Ontario, Canada. A total of 32 sampling stations were established in two wetland plant communities, 19 in an open Ericaceae low-shrub community and 13 in a closed Picea mariana and Larix laricina swamp community. Sphagnum was collected in each station for analysis of testate amoebae and measurement of soil water content parameters and water table depth in May, August, and October 2001. pH and dissolved oxygen of the groundwater under the Sphagnum were measured also. A total of 52 taxa including the rotifer, Habrotrocha angusticollis, were identified. Soil water content and water table variables emerged as the primary factors separating testate amoebae between the open bog/fen community and swamp community. Testate amoebae in the open bog/fen community showed a clear separation between the May sampling period and the August and October sampling periods. Sampling stations in May had much higher water table and were wetter than those in August and October. Conversely, testate amoebae in the swamp community did not show a clear difference between sampling periods. Soil moisture and water tables appear to be more constant in the swamp communities. Biological factors or other microscale environmental factors may need to be considered to explain seasonal changes in testate amoebae. A greater understanding of relationships between testate amoebae and microenvironmental factors is necessary to track seasonality in testate amoebae distributions.     

Palaeoecology of testate amoebae in a tropical peatland

We present the first detailed analysis of subfossil testate amoebae from a tropical peatland. Testate amoebae were analysed in a 4-m peat core from western Amazonia (Peru) and a transfer function developed from the site was applied to reconstruct changes in water table over the past ca. 8,000 years. Testate amoebae were in very low abundance in the core, especially in the lower 125 cm, due to a combination of poor preservation and obscuration by other organic matter. A modified preparation method enabled at least 50 testate amoebae to be counted in each core sample. The most abundant taxa preserved include Centropyxis aculeata, Hyalosphenia subflava, Phryganella acropodia and Trigonopyxis arcula. Centropyxis aculeata, an unambiguous wet indicator, is variably present and indicates several phases of near-surface water table. Our work shows that even degraded, low-abundance assemblages of testate amoebae can provide useful information regarding the long-term ecohydrological developmental history of tropical peatlands.     

The Potential Influence of Short-term Environmental Variability on the Composition of Testate Amoeba Communities in <Emphasis Type="Italic">Sphagnum</Emphasis> Peatlands

Testate amoebae are a group of moisture-sensitive, shell-producing protozoa that have been widely used as indicators of changes in mean water-table depth within oligotrophic peatlands. However, short-term environmental variability (i.e., sub-annual) also probably influences community composition. The objective of this study was to assess the potential influence of short-term environmental variability on the composition of testate amoeba communities in Sphagnum-dominated peatlands. Testate amoebae and environmental conditions, including hourly measurements of relative humidity within the upper centimeter of the peatland surface, were examined throughout the 2008 growing season at 72 microsites within 11 peatlands of Pennsylvania and Wisconsin, USA. Relationships among testate amoeba communities, vegetation, depth to water table, pH, and an index of short-term environmental variability (EVI), were examined using nonmetric multidimensional scaling and correlation analysis. Results suggest that EVI influences testate amoeba communities, with some taxa more abundant under highly variable conditions (e.g., Arcella discoides, Difflugia pulex, and Hyalosphenia subflava) and others more abundant when environmental conditions at the peatland surface were relatively stable (e.g., Archerella flavum and Bullinularia indica). The magnitude of environmental variability experienced at the peatland surface appears to be primarily controlled by vegetation composition and density. In particular, sites with dense Sphagnum cover had lower EVI values than sites with loose-growing Sphagnum or vegetation dominated by vascular plants and/or non-Sphagnum bryophytes. Our results suggest that more environmental information may be inferred from testate amoebae than previously recognized. Knowledge of relationships between testate amoebae and short-term environmental variability should lead to more detailed and refined environmental inferences.     

Testate amoebae colonizing a newly exposed land surface are of airborne origin

We hypothesized that at the very beginning of terrestrial ecosystem development, airborne testate amoebae play a pivotal role in facilitating organismic colonization and related soil processes. We, therefore, analyzed size and quantity of airborne testate amoebae and immigration and colonization success of airborne testate amoebae on a new land surface (experimental site “Chicken Creek”, artificial post-mining water catchment). Within an altogether 91-day exposure of 70 adhesive traps, 12 species of testate amoebae were identified to be of airborne origin. Phryganella acropodia (51% of all individuals found, diameter about 35–45 μm) and Centropyxis sphagnicola (23% of all individuals found, longest axis about 55–68 μm), occurred most frequently in the adhesive traps. We extrapolated an aerial amoeba deposition of 61 individuals d⁻¹ m⁻² (living and dead individuals combined). Although it would be necessary to have a longer sequence (some additional years), our analysis of the “target substrate” of aerial immigration (catchment site) may point to a shift from a stochastic (variable) beginning of community assembly to a more deterministic (stable) course. This shift was assigned to an age of seven years of initial soil development. Although experienced specialists are necessary to conduct these time-consuming studies, the presented data suggest that terrestrial amoebae are suitable indicators for initial ecosystem development and utilization.     

Testate amoebae and tintinnids as spatial and seasonal indicators in the intertidal margins of Guadiana Estuary (southeastern Portugal)

The present study gathers pioneering taxonomical and community data on testate amoebae and agglutinated tintinnids, analyzing their seasonal and spatial distribution patterns in the mesotidal system of the Guadiana Estuary, southeastern Portugal. To evaluate both groups’ potential as bioindicators in climate monitoring and paleoenvironmental reconstructions, their abundance, diversity and living proportions were compared to elevation in relation to mean sea-level, marine influence and to periods of elevated water levels. The distributions of testate amoebae and tintinnid total assemblages were also related to major physicochemical variables by means of multivariate analysis.From 49 surface sediment samples collected in winter and summer 2010, 17 species (25 strains) of testate amoebae were identified (in the 63 μm fraction). The Centropyxidae, mainly represented by Centropyxis aculeata, Centropyxis arcula and Centropyxis constricta, had the greatest density (71% of total individuals), while the Difflugidae represented the most species (82% of total species). Higher diversities and densities were observed in winter in the upper estuary, where salinity is negligible, and in the middle estuary where they are concentrated at the lower levels of the intertidal zone. Few or no individuals were observed in the highest marsh zones. In winter, dead testate amoebae were dominant, with empty tests accumulating in the sediments from post-mortem transport by high river discharge. In summer, an increase in the living fraction is observed, with living testate amoebae along the entire estuary, which could indicate that some species are able to live in the lower reaches of the estuary.Along with the testate amoebae, two species of agglutinated tintinnids (>63 μm), Stenosemella ventricosa and Tintinnopsis cf. lata, were abundant in the sediments. Their highest abundances were observed in summer. Living individuals were only recorded in summer, mainly in the vicinities of freshwater and sewage outflows, where elevated nutrient concentrations may be expected.The present study demonstrates that both testate amoebae and tintinnids have well defined patterns in their temporal and spatial distribution, offering high bioindicator potential in environmental/climate monitoring studies as well as in paleoenvironmental reconstructions.     

Evaluating the use of dominant microbial consumers (testate amoebae) as indicators of blanket peatland restoration

Peatlands represent globally-important ecosystems and carbon stores. However, large areas of peatland have been drained for agriculture, or peat has been harvested for use as fuel or in horticulture. Increasingly, these landscapes are being restored through ditch blocking and rewetting primarily to improve biodiversity and promote peat accumulation. To date we have little knowledge of how these interventions influence the microbial communities in peatlands. We compared the responses of dominant microbial consumers (testate amoebae) to drainage ditch restoration relative to unblocked ditches in a UK upland blanket peatland (Migneint, North Wales). Two techniques were used for restoration: (i) dammed ditches with re-profiling; and (ii) dammed ditches with pools of open water behind each dam. Testate communities in the inter-ditch areas changed markedly over time and between treatments illustrating the potential of this group of organisms as indicators of blanket peatland restoration status. However, the responses of testate amoebae to peat rewetting associated with restoration were partially obscured by inter-annual variability in weather conditions through the course of the experiment. Although there was considerable variability in the response of testate amoebae communities to peatland drain blocking, there were clearly more pronounced changes in samples from the dammed and reprofiled treatments including an increase in diversity, and the appearance of unambiguous wet-indicator species in relatively high abundances (including Amphitrema stenostoma, Archerella flavum, Arcella discoides type, Difflugia bacillifera and Difflugia bacillarium). This reflects a shift towards overall wetter conditions across the site and the creation of new habitats. However, water-table was not a significant control on testate amoebae in this case, suggesting a poor relationship between water table and surface moisture in this sloping blanket peatland. Our findings highlight the potential of testate amoebae as bioindicators of peatland restoration success; however, there is a need for caution as mechanisms driving change in the microbial communities may be more complex than first assumed. Several factors need to be taken into account when implementing biomonitoring studies in peatlands including: (i) the natural variability of the peatland ecosystem under changing weather conditions; (ii) any disturbance connected with the restoration procedures; and (iii) the timescales over which the ecosystem responds to the management intervention. Our results also suggest an indicator species approach based on population dynamics may be more appropriate for biomonitoring peatland restoration than examining changes at the community level.     

Relationships among testate amoebae (Protozoa), vegetation and water chemistry in five Sphagnum-dominated peatlands in Europe

To study the relationships between groups of organisms and the degree to which these relationships are consistent across major climatic gradients, we analysed the testate amoeba ( Protozoa ) communities, vegetation and water chemistry of one peatland in five countries: Switzerland, The Netherlands, Great Britain, Sweden and Finland, as part of the BERI (Bog Ecosystem Research Initiative) project. The relationships between the different data sets and subsets were investigated by means of detrended correspondence analysis, canonical correspondence analysis and Mantel permutation tests. The comparison of data on vegetation and testate amoebae showed that inter-site differences are more pronounced for the vegetation than for the testate amoebae species assemblage. Testate amoebae are a useful tool in multi-site studies and in environmental monitoring of peatlands because: (1) the number of species in Sphagnum -dominated peatlands is much higher than for mosses or vascular plants; (2) most peatland species are cosmopolitan in their distributions and therefore less affected than plants by biogeographical distribution patterns, thus differences in testate amoeba assemblages can be interpreted primarily in terms of ecology; (3) they are closely related to the ecological characteristics of the exact spot where they live, therefore they can be used to analyse small-scale gradients that play a major role in the functioning of peatland ecosystems. This study revealed the existence of small-scale vertical gradients within the vegetation and life-form niche separation in response to water chemistry. The deep-rooted plants such as Carex spp. and Eriophorum spp. are related to the chemistry of water sampled at or near the ground water table, whereas the mosses are not. Testate amoebae were shown to be ecologically more closely related to the chemistry of water sampled at or near the water table level and to the mosses than to the deep-rooted plants.     

Plants and testate amoebae as environmental indicators in cupriferous peatlands,New Brunswick,Canada

Vegetation, testate amoebae, and metal concentrations in water and soil (mostly peat) were studied in two copper-rich treed swamps located north of Sackville, New Brunswick, Canada. One of the sites is partly disturbed, characterized by bare soil nearly devoid of vegetation cover except for isolated patches of the moss species, Pohlia nutans, around seepages and small streams. Copper concentrations in soil and water samples were high but varied among plots. Values in soil samples were as high as 16,000 μg/g in the open area, with 4550 μg/g being the mean. The highest value in groundwater was 1540 μg/l, with 292 μg/l being the mean. Twenty-seven testate amoebae species were identified from soil samples. The most abundant species were Cyclopyxis arcelloides and Centropyxis spp. Principal component analysis and detrended correspondence analysis showed that their abundance was especially high in the open area where copper concentrations were high, while species diversity of testate amoebae was low in the open area. This study suggests potential use of mosses and testate amoebae as bio-indicators and bio-monitoring tools for metals such as copper.     

Structure and seasonal dynamics of the protozoan community (heterotrophic flagellates,ciliates, amoeboid protozoa) in the plankton of a large river (River Danube,Hungary)

Seasonal dynamics of all major protozoan groups were investigated in the plankton of the River Danube, upstream of Budapest (Hungary), by bi-weekly sampling over a 1-year long period. Sixty-one heterotrophic flagellate, 14 naked amoeba, 50 testate amoeba, 4 heliozoan and 83 ciliate morphospecies were identified. The estimated abundance ranges of major groups throughout the year were as follows: heterotrophic flagellates, 0.27–7.8×10⁶ ind. l^?1; naked amoebae, max. 3300 ind. l^?1; testaceans, max. 1600 ind. l^?1; heliozoans, max. 8500 ind. l^?1; ciliates, 132–34,000 ind. l^?1. In terms of biovolume, heterotrophic flagellates dominated throughout the year (max. 0.58 mm³ l^?1), and ciliates only exceeded their biovolume in summer (max. 0.76 mm³ l^?1). Naked amoeba and heliozoan biovolume was about one, and testacean biovolume 1–3, orders of magnitude lower than that of ciliates. In winter, flagellates, mainly chrysomonads, had the highest biomass, whilst ciliates were dominated by peritrichs. In 2005 from April to July a long spring/summer peak occurred for all protozoan groups. Beside chrysomonads typical flagellates were choanoflagellates, bicosoecids and abundant microflagellates (large chrysomonads and Collodictyon). Most abundant ciliates were oligotrichs, while Phascolodon, Urotricha, Vorticella, haptorids, Suctoria, Climacostomum and Stokesia also contributed significantly to biovolume during rapid succession processes. In October and November a second high protozoan peak occurred, with flagellate dominance, and slightly different taxonomic composition.     

The Ecology of Testate Amoebae (Protists) in Sphagnum in North-western Poland in Relation to Peatland Ecology

We studied the relationship between testate amoebae (Protozoa) communities and the depth to the water table (DWT), pH, conductivity, and microhabitat type in Sphagnum dominated peatlands of north-western Poland and built predictive (transfer function) models for inferring DWT and pH based on the testate amoebae community structure. Such models can be used for peatland monitoring and paleoecology. A total of 52 testate amoebae taxa were recorded. In a redundancy analysis, DWT and pH explained 20.1% of the variation in the species data and allowed us to identify three groups of taxa: species that are associated with (1) high DWT and low pH, (2) low DWT and low pH, and (3) high pH and mid-range DWT. Our transfer function models allow DWT and pH to be estimated with mean errors of 9.89 cm and 0.71 pH units. The prediction error of the DWT model and the tolerance of the species both increase with increasing dryness. This pattern mirrors the ecology of Sphagnum mosses: Species growing in wet habitats are more sensitive to change in water table depth than the species growing in drier microhabitats. Our results are consistent with studies of testate amoeba ecology in other regions, and they provide additional support for the use of these organisms in paleoecological and biomonitoring contexts.     

Contrasting Species—Environment Relationships in Communities of Testate Amoebae, Bryophytes and Vascular Plants Along the Fen–Bog Gradient

We studied the vegetation, testate amoebae and abiotic variables (depth of the water table, pH, electrical conductivity, Ca and Mg concentrations of water extracted from mosses) along the bog to extremely rich fen gradient in sub-alpine peatlands of the Upper Engadine (Swiss Alps). Testate amoeba diversity was correlated to that of mosses but not of vascular plants. Diversity peaked in rich fen for testate amoebae and in extremely rich fen for mosses, while for testate amoebae and mosses it was lowest in bog but for vascular plants in extremely rich fen. Multiple factor and redundancy analyses (RDA) revealed a stronger correlation of testate amoebae than of vegetation to water table and hydrochemical variables and relatively strong correlation between testate amoeba and moss community data. In RDA, hydrochemical variables explained a higher proportion of the testate amoeba and moss data than water table depth. Abiotic variables explained a higher percentage of the species data for testate amoebae (30.3% or 19.5% for binary data) than for mosses (13.4%) and vascular plants (10%). These results show that (1) vascular plant, moss and testate amoeba communities respond differently to ecological gradients in peatlands and (2) testate amoebae are more strongly related than vascular plants to the abiotic factors at the mire surface. These differences are related to vertical trophic gradients and associated niche differentiation.     

Testate Amoeba (Arcellinida,Euglyphida) Ecology along a Poor‐Rich Gradient in Fens of Western Poland

We investigated the relationships between testate amoebae (Arcellinida, Euglyphida), vegetation and water chemistry along environmental gradients in minerotrophic peatlands (fens) in western Poland. We hypothesized that: a) hydrochemistry significantly influences structure of testate amoeba communities, and b) testate amoeba communities are more closely correlated with the hydrochemical variables (environment) than with the vegetation data. Testate amoeba communities and vegetation from 71 sample plots were investigated together with the hydro‐chemistry and hydrology based on 16 environmental variables and vegetation composition. Testate amoeba communities revealed a distinctive poor‐rich gradient in analysed fens. Mineral‐rich habitats, which were dominated by brown mosses, were preferred by a higher number of taxa than acidic habitats, which were dominated by Sphagnum. We recorded a total of 107 testate amoebae taxa. The average species richness of testate amoebae for brown mosses was higher (20) than for Sphagnum (13). We found that testate amoebae communities were similarly correlated with vascular plants, mosses and environmental parameters. Results of direct ordination demonstrate that hydrology, pH, Mg²⁺ and sodium remain the most important environmental control for the entire data set. CCA showed that in case of brown mosses hydrology, sodium and oxygen affect testate amoeba communities significantly whereas in Sphagnum only sodium emerge as most significant determining testate amoeba assemblages. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Response of Sphagnum Peatland Testate Amoebae to a 1-Year Transplantation Experiment Along an Artificial Hydrological Gradient

Peatland testate amoebae (TA) are well-established bioindicators for depth to water table (DWT), but effects of hydrological changes on TA communities have never been tested experimentally. We tested this in a field experiment by placing Sphagnum carpets (15 cm diameter) collected in hummock, lawn and pool microsites (origin) at three local conditions (dry, moist and wet) using trenches dug in a peatland. One series of samples was seeded with microorganism extract from all microsites. TA community were analysed at T0: 8–2008, T1: 5–2009 and T2: 8–2009. We analysed the data using conditional inference trees, principal response curves (PRC) and DWT inferred from TA communities using a transfer function used for paleoecological reconstruction. Density declined from T0 to T1 and then increased sharply by T2. Species richness, Simpson diversity and Simpson evenness were lower at T2 than at T0 and T1. Seeded communities had higher species richness in pool samples at T0. Pool samples tended to have higher density, lower species richness, Simpson diversity and Simpson Evenness than hummock and/or lawn samples until T1. In the PRC, the effect of origin was significant at T0 and T1, but the effect faded away by T2. Seeding effect was strongest at T1 and lowest vanished by T2. Local condition effect was strong but not in line with the wetness gradient at T1 but started to reflect it by T2. Likewise, TA-inferred DWT started to match the experimental conditions by T2, but more so in hummock and lawn samples than in pool samples. This study confirmed that TA responds to hydrological changes over a 1-year period. However, sensitivity of TA to hydrological fluctuations, and thus the accuracy of inferred DWT changes, was habitat specific, pool TA communities being least responsive to environmental changes. Lawns and hummocks may be thus better suited than pools for paleoecological reconstructions. This, however, contrasts with the higher prediction error and species’ tolerance for DWT with increasing dryness observed in transfer function models.     

Light variability and mixotrophy: Responses of testate amoeba communities and shell δ13C values to a peatland shading experiment

Paleoecological records suggest that growing season length and/or cloudiness may affect peatland carbon accumulation and testate amoeba-based environmental reconstructions, highlighting a need to understand how light intensity affects microbial communities. We shaded plots on two peatlands for two years to examine effects on testate amoeba communities, the relative abundance of mixotrophic and heterotrophic testate amoebae, transfer-function performance, and δ¹³C values of two species of mixotrophic testate amoebae. Surprisingly, relative abundance of mixotrophic species increased in shade, although compositional changes did not affect transfer-function performance. Shading did not affect δ¹³C values of Hyalosphenia papilio and Heleopera sphagni, which ranged from −23.5 to −19.6‰ and −23.2 to −19.2‰, respectively. These δ¹³C values were higher than those of potential food sources and lower than literature-derived values for Chlorella, the zoochlorellae inhabiting mixotrophic testate amoebae. δ¹³C values thus suggest that these mixotrophic species obtain some carbon from Chlorella, although coupled dietary and isotope studies are needed to quantify this contribution. More research is needed to assess impacts of light variability on peatland microbial communities; however, carbon sources are recorded by δ¹³C values of testate amoebae, indicating potential for studies of carbon cycling and how mixotrophy varies temporally and spatially.     

Organic matter accumulation in a restored peatland: Evaluating restoration success

Recent advances in peatland restoration techniques have succeeded in establishing Sphagnum moss on the remnant cutover peat surface following peat extraction; however, evaluating restoration success remains a key issue. We argue that a Sphagnum-dominated peatland can only be considered functionally ‘restored’ once organic matter accumulation has achieved a thickness where the mean water table position in a drought year does not extend into the underlying formerly cutover peat surface. Here we monitor the spatio-temporal development of organic matter accumulation in a new peat layer for the first 8 years following the restoration of a Québec peatland and couple a simple acrotelm carbon accumulation model and ecohydrological model to assess peatland restoration success.We determined that organic matter accumulation increased from 2.3 ± 1.7 cm 4 years post-restoration to 13.6 ± 6.5 cm 8 years post-restoration. For comparison, at an adjacent non-restored section of the peatland organic matter accumulation was significantly lower (p < 0.001 for all years), with mean thicknesses of 0.2 ± 0.6 and 0.8 ± 1.2 cm for 24 and 28 years post-extraction, respectively. Given the mean summer water deficit at the site (?64 mm), our ecohydrological modeling results suggest that a 19-cm-thick moss layer would be required to offset the water table decrease induced by the summer water deficit. Given the current rate of organic matter accumulation, net primary productivity and the new peat layer decomposition rates determined using litter bags, we estimate it will take 17 years post-restoration to accumulate a 19-cm moss layer. Consequently, we argue that successful peatland restoration may be achieved in the medium-term and that our simple modeling approach can be useful in assessing the long-term impact of restoration on atmospheric carbon dioxide sequestration.     

Nested PCR assay for the rapid detection of Naegleria fowleri from swimming pools in Egypt

The free-living amoeboflagellate Naegleria fowleri is the only species infects humans world widely distributed. N. fowleri is the causative agent of very rare but severe brain infection called primary amoebic meningo-encephalitis (PAM), a rapidly fatal disease of the central nervous system mainly in immuno-compromised individuals. N. fowleri infects human through the entry of the nose, and it happens when human swimming or diving in warm freshwater, such as lakes, rivers and swimming pools. The disease is acute, and patients often die within 5–10 days and before the infectious agent can be diagnosed. Limited information is available about the existence of pathogenic N. fowleri, in Egypt, so the present of N. fowleri is an important public health. In the present study, we examined hundred water, dust and swap samples collected from 5 swimming pools in Cairo, Egypt. Based on morphological characteristics of trophozoite and cyst, flagellation test 56% of thermo-tolerant Naegleria like amoeba was detected. The incidence of thermo-tolerant free-living amoebae reached 84, 80and 70% from water, cotton swap and dust samples, respectively at cultivation temperature of 45 °C. The highest occurrence of thermo-tolerant amoebae were recorded in summer (100 & 87.5%) while the lowest one were recorded in winter (58 & 37.5%) in both water and dust samples, respectively. In swap samples, the highest occurrence of thermo-tolerant free-living amoeba was recorded in both summer and spring (100%), while the lowest one was recorded in winter (40%). N. fowleri was performed on 24 samples from a total of 56 (42.2%) samples which are positive by culture. Nested PCR using Mp2Cl5 gene primers that is unique to N. fowleri was carried out. The N. fowleri specific primer showed band at 166 bp against 24 of 56 (42.2%) samples. The majority of positive samples unique to N. fowleri was detected in water samples followed by swap samples and finally dust samples 14 of 24 (58%), 7 of 24 (29%), 3 of 24 (13%), respectively. In conclusion, swimming pools water may be the source of Naegleria invasion. The use of molecular methods to identify free-living amoebae N. fowleri could provide a more rapid means to diagnose infections caused by those amoebae.     

Testate amoeba response to acid deposition in a Scottish peatland

Peatlands around the world are exposed to anthropogenic or volcanogenic sulphur pollution. Impacts on peatland microbial communities have been inferred from changes in gas flux but have rarely been directly studied. In this study, the impacts of sulphuric acid deposition on peatland testate amoebae were investigated by analysis of experimental plots on a Scottish peatland almost 7 years after acid treatment. Results showed reduced concentration of live amoebae and changes in community structure which remained significant even when differences in pH were accounted for. Several possible explanations for the impacts can be proposed including taphonomic processes and changes in plant communities. Previous studies have inferred a shift from methanogenic archaea to sulphate-reducing bacteria in sulphate-treated peats; it is possible that the impacts detected here might relate to this change, perhaps through testate amoeba predation on methanotrophs.