Diversity Of Testate Amoebae Research Articles

Does microhabitat influence the testate amoebae communities in the Nameri National Park, northeastern India? A tropical forest perspective

The community structure of testate amoebae inhabiting different microhabitats (soil and tree-moss) within a tropical forest biome in Nameri National Park, northeastern India, was investigated. A total of 33 testate amoebae species belonging to 13 genera were identified. Species belonging to the class Lobosea constituted 73% of total testate amoebae density in the soil habitat, whereas the class Filosea constituted the most dominant forms (58%) in the moist tree-moss habitat. The relative abundance of species was higher in the tree-moss habitat compared to the soil habitats of the forest. Although multivariate analysis suggested a significant difference in assemblage patterns between the habitats, the turnover in species (i.e., beta diversity) was insignificant. Species accumulation curves (SAC) constructed using both parametric and non-parametric species richness estimators revealed that the asymptote of species richness was achieved by a low number of sample replicates in both habitats. The temperature and pH of the substratum on testate amoebae distribution patterns suggest the importance of additional background factors on testate amoebae community structure. Further studies involving more biotopes, seasons, and trophic interactions are recommended to document a complete record of testate amoebae diversity and their interactions with environmental gradients in the tropical forest biomes of northeastern India.

Seasonal Changes in the Density and Species Diversity of Testate Amoebae in the Teteriv River (the Town of Zhytomyr)

Results of the study of seasonal changes in the density and species diversity of testate amoebae in the Teteriv River (the town of Zhytomyr) carried out in 2014-2015 are given in the paper. Relationship between these indices and water temperature, dissolved oxygen concentration, and organic matter content was analyzed.

Testate Amoebae in Karst Caves of the Dinaric Arc (South-Eastern Europe) with a Description of Centropyxis bipilata sp. nov.

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.

Diversity and distribution of testate amoebae (Amoebozoa, Rhizaria) in reservoirs, Northeastern Bulgaria

Abstract 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.

Ecological drivers of testate amoeba diversity in tropical water bodies of central Mexico

Testate amoebae are unicellular organisms characterized by a shell-like test. Due to their potential use as bioindicators (and paleoindicators), these organisms have been increasingly studied in the last decade, particularly in temperate latitudes. This study’s objective was two-fold: to identify the testate amoeba communities sampled from 29 water bodies in Mexico and to determine if their presence and distribution also made them suitable bioindicators for tropical latitudes. A total of 40 taxa were recorded within 12 genera, and six significant variables—oxygen, pH, depth, temperature, conductivity, and total alkalinity—that explained testate amoeba distribution within and among the water bodies were identified through a canonical correspondence analysis. The Q-mode clusters rendered five assemblages, each named after their respective dominant species: 1) Centropyxis aculeata strain “aculeata” assemblage, 2) Difflugia oblonga strain “bryophila” assemblage, 3) Diverse assemblage, 4) Cucurbitella tricuspis assemblage, and 5) Difflugia protaeiformis strain “acuminata” assemblage. We found that Cucurbitella tricuspis and the Difflugia protaeiformis strain “acuminata” have similar ecological preferences to those reported previously for temperate lakes, with the former identified as an indicator of eutrophic environments and the latter as an indicator of low oxygen levels. On the other hand, Centropyxis aculeata strain “aculeata” and Arcella vulgaris seem to indicate adverse conditions, but the source of this environmental stress apparently differs from that reported in temperate latitudes. Although this stress source could not be identified in all cases, our study nonetheless demonstrates that testate amoebae in the water bodies of central Mexico could reveal the presence of environmental stress.

<b>Species composition of testate amoebae in Lake Monte Alegre, Ribeirão Preto, SP, Brazil

We aimed to perform the first survey of testate amoebae community composition in Lake Monte Alegre at Sao Paulo state, and contribute to mitigate the taxonomic impediment regarding the diversity of testate amoebae in Brazil. Samplings were performed in 20 sampling sites within the lake, in the limnetic and littoral regions in April 2015, using a 58 µm-meshplankton net. We identified 20 taxa of testate amoebae belonging to four families: Arcellidae (8 taxa), Centropyxidae (4 taxa), Difflugiidae (7 taxa) and Lesquereusiidae (2 taxa). The littoral region showed the highest number of taxa (n = 20), whereas in the limnetic region 11 taxa were registered. Therefore, our results evidenced the importance of testate amoebae in aquatic systems, and that further research, taxonomic and/or ecological, in those environments should include these organisms in their investigation. Moreover, we suggest that future research with greater sampling effort is necessary to expand the identification of possible cryptic species in this environment.

Impact of two hot and dry summers on the community structure and functional diversity of testate amoebae in an artificial bog, illustrating their use as bioindicators of peatland health

Impact of two hot and dry summers on the community structure and functional diversity of testate amoebae in an artificial bog, illustrating their use as bioindicators of peatland health

Late Quaternary climatic variability in the Central Ganga Plain: A multi-proxy record from Karela Jheel (Lake)

A multi-proxy study involving phytoliths, diatoms, thecamoebians and sponge spicules was carried out on a trench profile (260 cm deep) from Karela Lake in the Central Ganga Plain to reconstruct climatic variations since ca. 17,000 cal BP. The testate amoebae record indicate spells of winter monsoon between ca. 17,000 cal BP and 13,700 cal BP. Increased diversity of diatoms, testate amoebae and sponge spicules, in addition to low Humidity/Aridity Index (Iph) values suggest strengthened monsoon inducing the expansion of lake margin and high primary productivity during ca. 13,700 to 4300 cal BP. Further between ca. 4300 and 2900 cal BP, higher Iph values and related responses of other studied proxies show a stressed lake ecosystem. Since ca. 2900 cal BP, area of the lake was reduced responding to low intensity of the Indian Summer Monsoon. Anthropogenic activities may also have played a role in the lake shrinking at least during some parts of this duration.

Contrasting diversity of testate amoebae communities in Sphagnum and brown-moss dominated patches in relation to shell counts

Ecological studies of peatland testate amoebae are generally based on totals of 150 individuals per sample. However, the suitability of this standard has never been assessed for alkaline habitats such as spring fens. We explored the differences in testate amoeba diversity between Sphagnum and brown-moss microhabitats at a mire site with a highly diversified moss layer which reflects the small-scale heterogeneity in groundwater chemistry. Relationships between sampling efficiency and sample completeness were explored using individual-based species accumulation curves and the effort required to gain an extra species was assessed. Testate amoeba diversity differed substantially between microhabitats, with brown mosses hosting on average twice as many species and requiring greater shell totals to reach comparable sample analysis efficiency as for Sphagnum. Thus, for samples from alkaline conditions an increase in shell totals would be required and even an overall doubling up to 300 individuals might be considered for reliable community description. Our small-scale data are likely not robust enough to provide an ultimate solution for the optimization of shell totals. However, the results proved that testate amoebae communities from acidic and alkaline environments differ sharply in both species richness and composition and they might call for different methodological approaches.

Diversity and community patterns of testate amoebae in Bau Sen and Bau Trang lakes in Binh Thuan Province, Vietnam

The species composition and distribution of testate amoebae in Bau Sen and Bau Trang lakes (Binh Thuan Province, Vietnam) were investigated. Fifty-three species, varieties and forms have been identified from the water column and sediments. Twenty-seven species, varieties and forms from the genera Arcella, Centropyxis, Cyclopyxis, Difflugia and Pyxidicula were found in Vietnam for the first time. The updated list of testate amoebae in Vietnam now includes 286 taxa. The genera Arcella, Centropyxis and Difflugia are characterized by the highest frequency of occurrence. The species diversity of Arcella, Centropyxis, Difflugia was the highest. Centropyxis aculeata, Arcella discoides, Difflugia schurmanni, Netzelia oviformis and Difflugia limnetica were the most common species. Many species have shown restricted distribution, some species have been found only in one lake and not been found in another lake. The number of observed species, varieties, and forms in each lake is 34. The average number of the species per sample on the shores of the lakes subjected to human agricultural activity was significantly higher than in the samples from the shores of the lakes with less anthropogenic disturbance. The curves of “cumulative species number vs. sampling effort” are well fitted by equations S = 7.60 N 0.69 for Bau Sen lake and S = 12.52 N 0.46 for Bau Trang. The curves are unsaturated, which indicates that more intensive investigations of testate amoebae should be expected to reveal more species.

Exploring the diversity and ecology of testate amoebae in West Siberian peatlands

Testate amoebae are valued for their functional significance and application as indicators of environmental conditions, particularly in peatland ecosystems. Research on testate amoebae has increased dramatically in recent years but there are still large parts of the world which have seen very little research. Here we consider testate amoeba communities of the West Siberian Lowland, the world’s largest peatland region and therefore one of the largest potential habitats for testate amoebae. Extensive sampling identified 89 taxa and showed that testate amoeba communities are structured by their physical and biological environment. We identified significant relationships between amoeba communities and both moisture content and vegetation composition. Despite the assemblages containing many widely-distributed species, some taxa considered typical of peatlands (e.g. Archerella flavum and Hyalosphenia papilio) were comparatively rare or absent, paralleling findings further south in Asia. We suggest that testate amoebae in this region deserve further study and may have useful applications in palaeoecological reconstruction and as bioindicators of the impacts of oil and gas extraction.

Testate Amoeba Diversity of a Poor Fen on Mineral Soil in the Hilly Area of Central Honshu, Japan

We present a short note on the species composition of testate amoebae in a poor fen on mineral soil near the Pacific Coast in the hilly area of Central Honshu, Japan. In total 45 species and subspecific taxa belonged to 21 genera and 14 families of testate amoebae were recorded. Eight species and nine subspecies are newly recorded from Japan. However, most species from the list can be considered as distributed worldwide and associated mostly to oligotrophic/acid Sphagnum conditions.

Temporal dynamics and environmental predictors on the structure of planktonic testate amoebae community in four Neotropical floodplains

ABSTRACTUnderstanding the environmental factors that control community structure has become a major focus of ecological research in recent decades. Here, we aimed to analyze the structure of planktonic testate amoebae community and the impact of environmental variables on the diversity of planktonic species in four floodplains of Brazil (Amazonian, Araguaia, Paraná, and Pantanal) over two hydrological periods (2011 and 2012). We hypothesized that biological diversity (richness, abundance, and diversity) of the testate amoebae community is higher during drought periods. Samples were collected from the subsurface of the limnetic region of 72 lakes in the four floodplains during both drought and flood periods in both years. We identified 109 species, belonging to 11 families. Difflugiidae and Arcellidae exhibited higher species composition and abundance. ANOVA results showed noticeable temporal variation in testate amoebae community structure. We confirmed that the highest richness, abundance, and diversity were primarily recorded during drought periods, with significant differences being documented among floodplains and across the two hydrological periods. Multiple regression analysis also indicated that testate amoebae diversity is related to the productivity of the environments in the Amazonian, Araguaia, and Paraná floodplains. Depth of lakes and phosphorus appeared to be limiting factors in the Paraná and Araguaia floodplains, while dissolved oxygen limited species diversity in the Pantanal floodplain. Our results highlight that testate amoebae community exhibit the greatest biological diversity during drought periods, while species diversity is influenced by the environmental conditions (primarily productivity) of each floodplain.

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%, >80μm) 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.

Testate Amoebae Like It Hot: Species Richness Decreases Along a Subalpine-Alpine Altitudinal Gradient in Both Natural Calluna vulgaris Litter and Transplanted Minuartia sedoides Cushions.

Most groups of higher organisms show a decrease in species richness toward high altitude, but the existence of such a pattern is debated for micro-eukaryotes. Existing data are scarce and mostly confounded with the diversity of habitats that also decreases with elevation. In order to disentangle these two factors, one approach is to consider only similar types of habitats occurring across an elevational gradient. We assessed the diversity and community structure of testate amoebae in two specific habitats: (1) natural Calluna vulgaris litter and (2) Minuartia sedoides cushions 7 years after their transplantation along a vertical transect from 1770 to 2430 m in the subalpine and alpine zones of the Swiss Alps. Analyses of co-variance and variance showed that testate amoeba species richness, equitability, and diversity declined with elevation and were significantly correlated to habitat type. In a redundancy analysis, the variation in the relative abundance of the testate amoeba taxa in Calluna vulgaris litter was equally explained by elevation and litter pH. This is the first study documenting a monotonic decrease of protist diversity in similar habitats across an elevational gradient.

Use of functional diversity to assess determinant assembly processes of testate amoebae community

Functional diversity is among the main components of biodiversity, by quantifying the characteristics of organisms and by investigating which assembly processes prevail in the organisation of communities. The objective of this study was to assess the functional diversity of testate amoebae in floodplains, verifying whether the determinant assembly process of the community is related to environmental filters or the limiting similarity. We tested the hypothesis that the functional diversity of the testate amoebae would be lower than randomly expected in the hydrological periods, influenced by environmental filters. In addition, the functional diversity of the testate amoebae was expected to be strongly influenced by variables related to the productivity of the environments, since the food resources are the most important environmental factors in the assembly of testate amoeba communities. Sampling was carried out quarterly between 2002 and 2011 on the surface of the pelagic zone in six floodplain environments. Results showed that the values were lower than randomly expected according to the functional diversity indices. In addition, the functional diversity was predicted by the environmental variables related to the productivity of the environments according to multiple regression analyses. Our results highlight that functional diversity was mainly influenced by the environmental filters. The limiting similarity and neutral processes could not be totally discarded, and the three mechanisms of community assembly can occur. The environmental filters were linked to productivity and consequently to food resources, which are determinant in the assembly of the testate amoebae community, corroborating our predicted hypothesis.

Testate Amoebae Diversity, from the Atlantic Forest Aquatic and Edaphic Environments, Collected Within the Rio de Janeiro State, Brazil

Testate Amoebae Diversity, from the Atlantic Forest Aquatic and Edaphic Environments, Collected Within the Rio de Janeiro State, Brazil

Checklist, diversity and distribution of testate amoebae in Chile

Bringing together more than 170 years of data, this study represents the first attempt to construct a species checklist and analyze the diversity and distribution of testate amoebae in Chile, a country that encompasses the southwestern region of South America, countless islands and part of the Antarctic. In Chile, known diversity includes 416 testate amoeba taxa (64 genera, 352 infrageneric taxa), 24 of which are here reported for the first time. Species−accumulation plots show that in Chile, the number of testate amoeba species reported has been continually increasing since the mid-19th century without leveling off. Testate amoebae have been recorded in 37 different habitats, though they are more diverse in peatlands and rainforest soils. Only 11% of species are widespread in continental Chile, while the remaining 89% of the species exhibit medium or short latitudinal distribution ranges. Also, species composition of insular Chile and the Chilean Antarctic territory is a depauperated subset of that found in continental Chile. Nearly, the 10% of the species reported here are endemic to Chile and many of them are distributed only within the so-called Chilean biodiversity hotspot (ca. 25° S-47° S). These findings are here thoroughly discussed in a biogeographical and evolutionary context.

Diversity and community ecology of forest epiphyte testate amoebae from European Russia

Testate amoebae are an abundant group of microorganisms which make a significant contribution to the diversity of protist life. Most of the world's potential habitats for testate amoebae have been barely studied and when such places are investigated they frequently reveal novel communities and species. Here we consider the testate amoeba communities associated with boreal forest epiphytes (mosses and lichens); an environment which we argue has been under-researched. We present a dataset of 165 samples from four regions of western Russia and analyse these data in relation to micro-habitat position and selected environmental data. The testate amoebae of epiphytes are abundant but dominated by ubiquitous species. We show that there are trends toward a lower species richness and test concentration with greater elevation on the trunk and in lichens compared to mosses. There are considerable differences in community composition between sampling regions. Of all measured environmental variables only moisture content showed a significant relationship with testate amoeba community structure. Our data highlight how little is known about testate amoeba communities of this habitat and call for greater research efforts, particularly in less-studied regions and biomes.

Arcella peruviana sp. nov. (Amoebozoa: Arcellinida, Arcellidae), a new species from a tropical peatland in Amazonia

There has only been one study on the ecology of testate amoebae from Amazonian peatlands, despite Amazonia being a biodiversity hotspot of global importance. During analysis of litter samples from Aucayacu peatland, western (Peruvian) Amazonia, we discovered a testate amoeba with a distinct morphology unlike any other species reported previously. We describe a new species, Arcella peruviana, based on its distinct morphology, compare it to morphologically similar species and provide information about its ecology. This new species is characterised by a distinct cruciform aperture (diameter ranges between 12 and 17μm) which is slightly invaginated. The test is small (height 43–57μm) and polygonal in cross-section. Our discovery suggests the existence of an unknown diversity of testate amoebae in Amazonia. The absence of the new Arcella species in more intensively-sampled regions supports the view that protists have restricted distributions.