Elemental Composition of the Shell of the Testate Amoeba Difflugia tuberspinifera (Sarcodina:Rhizopoda)

X-ray microanalysis was used to study the elemental composition of the shell of the freshwater testate amoeba Difflugia tuberspinifera Hu et al.,1997 collected from Mulan Lake,Hubei province,China in July 2003.The results show that the shell is composed of ten elements:Si in greater quantity;then Ca and Al;and traces of K,Na,Cl,Fe,Mg,S and P.The analysis of results suggests that D.tuberspinifera in elemental composition appears to occupy a middle position between marine and soil testate amoebae.

Ecology of testate amoebae in Dajiuhu peatland of Shennongjia Mountains, China, in relation to hydrology

This study investigates the testate amoeba communities of a large peatland in Central China. The ecology and seasonal variability of testate amoeba communities were studied during 2009-2010. Investiga- tion of environmental controls using ordination showed that the relationship between testate amoeba communities and depth to water table （DWT） and pH are extremely weak. The small proportion of variance explained by water table depth here （only 1.9% in the full data） shows that the hydrological control is weaker than we expected in this peatland, and weaker than any study we are aware of using a similar methodology. Attempts to develop species- environment （transfer function） models or identify indi- cator species for future palaeoecological studies were unsuccessful. Previous large-scale studies of peatland testate amoeba ecology have been largely restricted to Europe and North America and results have been relatively consistent among studies. Our results contrast with this consensus and suggest that at least in minerotrophic peatlands in China testate amoeba communities may be primarily controlled by different environmental variables. In China, testate amoebae have been relatively little studied but may prove to be valuable for a variety of applications in palaeoecology and biomonitoring and much further work is required.

Testate amoebae communities from some freshwater and soil habitats in China （Hubei and Shandong Provinces）

Seventy-eight species and forms of testate amoebae were identified from 29 freshwater and soil habitats in three territories of China （Shandong and Hubei Provinces）. Most abundant species from the genera Plagiopyxis, Centropyxis and Trinema represent the globally-distributed and eurybiont group of testate amoe- bae. The species richness was observed to be the lowest （7-12 species per biotope） in sandy sediments of the Yangtze River, but considerably higher （20-30 taxa） in soil environment. In the range of terrestrial habitats, the most remote communities from Laoshan Mountain in Shandong Province, China manifested the highest difference from others. On the other hand, communities originated in the most distant from industrial center places （Guifeng Mountain in Hubei Province, China） possess the most peculiar species composition including specific Gondwa- nian taxa （e.g. Nebela bigibbosa）. In sum, the results obtained provide the evidence that the community complexity and specificity reduce in the places located within areas that are highly populated and intensively visited by humans.

Ecology of testate amoebae and their potential use as palaeohydrologic indicators from peatland in Sanjiang Plain, Northeast China

Testate amoebae are sensitive indicators of substrate moisture in peaflands. Over the last decades, they have been studied to reconstruct hydrological changes since the Holocene. However, these studies have been geographically restricted to North America and Europe. We conducted the first investigation of testate amoebae on the largest continental fresh water wetland in the Sanjiang Plain, China. The objectives of this study were to provide baseline data on the ecology of testate amoebae in the peatlands of Northeast China and to assess the potential of using them as environmental indicators in this ecosystem. We examined modem testate amoeba assemblages and species-environmental relationships at 46 microsites within 5 waterlogged depressions. The environmental parameters measured included： depth to water table, pH, and loss on ignition. The results showed that the dominant species were Trinema complanatum type, Euglypha rotunda type, Euglypha strigosa type, and Centropyxis cassis type. Redundancy analysis demonstrates that water table depth has the most important effect on testate amoeba assemblages, explaining 16.7% （p=0.002） of the total variance, pH was not a statistically significant factor for testate amoeba assemblages. Weighted averaging and weighted averaging partial least squares models were used to build transfer functions for depth to water table. The best performing transfer function was generated by the weighted averaging partial least squares model with an r^2LOSO of 0.62 and RMSEPLoso of 6.96 era. Results indicate that testate amoebae in waterlogged depression peatland have the potential to be used as indicators for hydrological changes and for palaeohydrologic reconstructions in the Sanjiang Plain.

Relationships between testate amoeba communities and water quality in Lake Donghu, a large alkaline lake in Wuhan, China

The middle Yangtze Reach is one of the most developed regions of China. As a result, most lakes in this area have suffered from eutrophication and serious environmental pollution during recent decades. The aquatic biodiversity in the lakes of the area is thus currently under significant threat from continuous human activities. Testate amoebae （TA） are benthic （rarely planktonic） microorganisms characterized by an agglutinated or autogenous shell. Owing to their high abundance, preservation potential in lacustrine sediments, and distinct response to environmental stress, they are increasingly used as indicators for monitoring water quality and reconstructing palaeoenvironmental changes. However this approach has not yet been developed in China. This study presents an initial assessment of benthic TA assemblages in eight lakes of Lake Donghu in the region of Wuhan, China. Testate amoeba community structure was most strongly correlated to water pH. In more alkaline conditions, communities were dominated by Centropyxis aculeata, Difflugia oblonga, Pontigulasia compressa, Pon. elisa and Lesquereusia modesta. These results are consistent with previous studies and show that TA could be useful for reconstructing past water pH fluctuations in China. To achieve this, the next step will be to expand the database and build transfer function models.

应用rioja软件包建立有壳变形虫-环境因子转换函数

应用R语言rioja软件包的加权平均(Weighted Averaging,WA)和加权平均偏最小二乘(Weighted AveragingPartial Least Squares,WA-PLS)模型建立了长白山区泥炭藓泥炭地有壳变形虫与水位埋深(depth to water table,DWT)、pH和泥炭湿度的转换函数,为古环境定量重建奠定了基础,也提供了rioja软件包应用的实例和参考。结果表明水位埋深以WA-PLS模型最佳(预测均方根误差RMSEP为7.39 cm,R2=0.74);对于pH和泥炭湿度,WA-PLS第一分量和WA.inv都产生了最小的RMSEP和较高的R2值。pH的RMSEP为0.18,R2为0.72。泥炭湿度的RMSEP为1.95%,R2为0.62。如果泥炭剖面的有壳变形虫种类组成与本研究的训练样本集相同,水位埋深、pH和泥炭湿度可以分别以±7.39 cm、±0.18和±1.95%的平均误差进行重建。