-The testate amoebae communities living among different species of mosses in Sphagnum peatlands in eastern Poland were studied. Sampling was done on a monthly basis from April to November [2005][2006][2007]. To assess the importance of the vertical distribution of testate amoebae within the mosses, each sample was cut into two parts: the upper living part (1-5 cm) and the lower dead part (5-10 cm). The highest species richness occurred in hollows dominated by Sphagnum angustifolium, Sphagnum flexuosum and Sphagnum palustre. Lower numbers of taxa were observed in hummocks dominated by Sphagnum magellanicum, Polytrichum strictum and Polytrichum commune. There was a distinct horizontal micro-zonation of the abundance of testate amoebae occurring among Sphagnum mosses, but only a small difference ascertained among Polytrichum. The number of testate amoebae was significantly greater in the deeper samples. The results demonstrated that depth to water table, pH and total organic carbon can strongly regulate the abundance and taxonomic composition of testate amoebae.

Abstract:There are hardly any data concerning the vertical micro−distribution of protozoa in water column in cryoconite holes on the glacier surface. Such comparisons can provide in− sights into the ecology of protozoa. The present research was made on Ecology Glacier (South Shetland Islands, Antarctic); vertical microzonation of ciliates in relation to physical and chemical parameters in cryoconite holes was studied. The density and biomass of protozoans significantly differed between the studied stations (cryoconite holes), with the lowest num− bers in the surface water and the highest in the bottom water. The surface waters were domi− nated by mixotrophic and omnivorous taxa, whereas the deepest sampling level has shown the increase of the proportion of bacterivore species. Ordination analysis indicated that TN and P−PO 4 can strongly regulate the abundance and species composition of protozoa. The redun− dancy analyses (RDA) showed that the ciliate communities can be separated into two groups. The first group included species associated with surface water: Halteria grandinella and Codonella sp. The second group included species that are associated with bottom water: Prorodon sp., Holosticha pullaster, Stylonychia mytilus−complex and small scuticociliates.

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The aim of this study was to examine the community structure and vertical micro-distribution of testate amoebae and ciliates in a raised bog in eastern Poland, as well as to assess the influence of potential food resources (Chl-a, bacteria, heterotrophic flagellates) and predators (rotifers and copepods) on protozoa communities. Samples were taken from surface, bottom and interstitial waters. At each type of micro-habitat and each sampling date water was sampled using a plexiglass corer or mini-piezometers. Additionally, in order to evaluate grazing pressure, field enclosures were used in which metazoan abundance and composition was manipulated by size-fractionation. Over experiments, metazoan populations shifted from dominance of rotifers to copepods. In the first experiment, with rotifers dominating, metazoa had only a modest predatory impact on the protozoa. In contrast, the second experiment, with copepods prevailing, demonstrated a clear top-down control of the protozoa communities by metazoan. The density and biomass of protozoa significantly differed between the studied stations, with the lowest numbers in the interstitial water and the highest in the surface water. Surface sampling were dominated by mixotrophic taxa, whereas the deepest sampling level was characterized by increase in the proportion of bacterivore species. These differences between micro-habitats may be due to differences in environmental conditions (food resources and grazing pressure). Ordination analysis revealed that bacteria can strongly regulate the abundance and taxonomic composition of protozoa in the bottom and interstitial waters. Metazoan predators could be the main regulators of protozoa communities in surface water.

-The testate amoeba, ciliate and rotifera communities living in interstitial waters in peatbog in eastern Poland were studied. Sampling was done on a monthly basis from April to November 2007-2008. Microbial communities were examined in a transect including three sites: (1) pine forest (site located 5 m from the lagg/forest contact zone), (2) lagg, (3) open peatbog (the centre of the peatbog). At each of the sites, interstitial water was sampled by means of piezometric wells placed to a depth of 1 m. The species richness and abundance of protozoa and rotifers significantly differed between the studied stations, with the lowest numbers in the pine forest and the highest in the lagg. These differences between macro-habitats may be due to differences in environmental conditions. The distribution of samples in ordination space led to conclude that studied habitats are distributed along the falling gradient of pH and rising gradient of total organic carbon, water table depth and nitrate nitrogen. Assemblages of all three groups showed a strong compositional gradient correlated with water-table depth, conductivity and total phosphorus. However, species composition of ciliates and rotifers was explained by nitrate nitrogen and/or phosphates concentrations. The results suggest that lagg zone of a raised bog can fulfil the function of an ecotone zone, distinguished by a significant increase in biodiversity, abundance and species specificity of micro-organisms. It can also be a place of very efficient matter and energy flow in a peat bog ecosystem.

Complex interactions between bacteria and protists are essential to the ecosystem ecology of peatbogs. However, little is known about how short-term changes in environmental conditions may influence microbial and metazoan communities. Microbial processes and parameters may be used as sensitive indicators of eutrophication. We address the hypothesis that an increase in the concentration of nutrients (in an experiment simulating eutrophication) will affect species richness and abundance of microorganisms and small metazoans and will cause changes in food web structure in different types of peatbogs. The experiments were performed in a Sphagnum peatland and a carbonate fen. Four experimental treatments were established (control and fertilised: +P, +N, P+N). An increase in habitat fertility was found to modify the taxonomic composition and functioning of microbial communities. This was reflected in a decrease in the species richness of testate amoebae and a substantial increase in the abundance of bacteria, flagellates and ciliates in both types of peatbogs. A better understanding of which parameters regulate microbial populations in peatbogs is critical for more accurate prediction of how peatbogs will respond to global change or anthropogenic disturbances.

Body size, community structure, abundance and biomass of ciliates were compared in various stands of macrophytes in a macrophyte-abundant shallow lake in Eastern Poland. Samples were collected in belts of Phragmites, Typha, Ceratophyllum, Elodea, Stratiotes and Chara. Additionally, protozooplankton was collected from the open water zone surrounding the vegetation belts. Differences in numbers of ciliate taxa between micro-sites were statistically significant. The highest numbers were found in Chara and Ceratophyllum stands, lower numbers in Stratiotes and Elodea stands and the lowest in the open water, Phragmites and Typha areas. Ciliate biomass was, like density, significantly higher in submerged macrophytes than in emergent macrophytes and open water zones. Based on differences in macrophyte structure, two groups of habitats with similar patterns of size-related ciliate distribution were distinguished. The first group consisted of two vegetated zones of sparse stem structure (Phragmites and Typha) and the open water zone, the second group comprised submerged macrophyte species, which were more dense and complex. Generally, the abundance of ciliates correlated positively with total suspension solid (TSS) and total organic carbon (TOC) concentrations. In the Chara and Ceratophyllum stands, relations between ciliate numbers, TSS and TOC were stronger.

Moss-inhabiting rotifers were studied in 2 raised bogs, 2 poor fens (i.e. intermediate between raised bogs and typical fens), 1 typical fen, and 1 base-rich fen, located in the Polesie National Park (eastern Poland). Moss samples were collected from April till November 2007 in monthly intervals. In total, 42 taxa of Monogononta and 26 of Bdelloidea were found. Analysis of variance (ANOVA) detected highly significant differences between the habitats in conductivity (F = 37.19, P < 0.001), total organic content (F = 9.34, P < 0.001), total P (F = 51.71, P < 0.001), and nitrate N (F = 48.98, P < 0.001). The mean density of rotifers was the highest in a bog dominated by Sphagnum angustifolium JENSEN (Durne Bagno), and the lowest in the base-rich fen (Bubnów). In all the studied habitats, the Bdelloidea were the most abundant, accounting for 56 to 85% of the total rotifer density. Canonical correspondence analysis (CCA), made for selected physicochemical parameters and taxa, confirms strong relationships between abiotic conditions and selected rotifer taxa: Habrotrocha angusticolis, Dicranophorus capucinus, Ke ratella serrulata, and Lepadella elliptica. IntroductionPeatlands are systems composed of peat deposits and the specific vegetation that covers them (RADWAN, 2002). Various types of peatlands are distinguished depending on hydrological conditions, pH, nutrient concentrations, as well as vegetation type (BRINGHAM et al., 1996). Those habitats are characterized by continuous changes in environmental conditions, such as pH, temperature, and oxygen content (RADWAN, 1974). Low pH, concentrations of nutrients, and temperature, as well as oxygen deficits, make the environment of Sphagnum mats extremely unfavourable for many organisms ( VAN BREEMAN, 1995). In spite of the harsh environmental conditions in bogs and peatland ecosystems, rotifers are able to live in them. Several authors believe that low values of pH (below 5) greatly limit the distribution and abundance of many rotifer species (RADWAN, 1984;BERZINS and PEJLER, 1987). However, a large number of rotifer species show a broad range of pH tolerance and some bdelloid species are tolerant to a very broad pH spectrum (BERZINS and PEJLER, 1987). Another factor that limits the distribution of organisms in peatlands is the availability of water (MITCHELL et al., 2003). However, Sphagnum mats are able to store large amounts of water, so they create favourable living conditions for rotifers (BŁĘDZKI and ELLISON, 2003). Rotifers are most abundant in moss (SAYRE and BRUNSON, 1971), and that is why they are an excellent tool for epiphyton research in peatland ecosystems.There are many publications on rotifer diversity in lakes, ponds, artificial water bodies, and running waters, but few studies on rotifers in other aquatic habitats (FONTANETO et al., 2005). Particularly little is known about moss-dwelling rotifers in peatlands (BŁĘDZKI and ELLISON, 2003;BATEMAN and DAVIS, 1980). Many more studies have concerned aquatic habitats closely related to peatlands, i.e....