The testate amoebae in Sphagnum peatlands in Changbai Mountains

Testate amoebae are a group of unicellular protozoa living in moist soil, freshwater habitats such as lake, river and petland. They are especially diverse and abundant in Sphagnum peadands. Because of their decay -resistant shells and clear responses to the main environmental gradients in peadands, such as wetness and pH, they have a great potential to be a proxy in paleoenvironment reconstruction. Although many studies on modem ecology and paleoecology of testate amoeba have been conducted in different regions of the world, particularly in Europe and North America, there are few researches on testate amoebae done in China. And we have even less knowledge about testate amoebae in peadands in China. During July and August, 2008, 75 samples were collected along the hydrological gradient from 4 peadands namely Hani(42° 12′50″N, 126°31′05″E), Jinchuan(42°20′ 47″N, 126°21′35″E), Chichi(42°03′16″N, 128°03′22″ E) and Yuanchi(42°01′55″N, 128°25′58″E), in Changbai Mountains, northeast China. All sampling spots were dominated by Sphagnum and covered different habitats including the hollow, the top, middle and low part of hummock. Depth to water table ( DWT) , moisture of peat, pH and conductivity were measured on spot. Latitude, longitude and altitude were recorded with GPS. After identified with the light microscope under 100 × and 400 × magnification, a total of 33 testate amoebae taxa and 12 984 tests were recorded in 75 samples. All of these 33 taxa were often founded in studies in other regions of the world. The dominant taxa are Assulina muscorum, Cyclopyxis arcelloides type, Croythion - Trinema type, Hyalosphenia eleglans, Euglypha tuberculata type, Centropyxis cassis type, Nebela tincta, Heleopera sphagni. Especially Assulina muscorum, it occurred in all samples and accounted for 26.26% of tests counted. While Lesquereusia spiralis occurred only in three samples and accounted for 0.08% of tests. The presences of Nebela lageniformis and Quadrulella symmetrica in four peadands show diat these peadands are influenced by minerotrophic water supply and Uiey are still in minerotropic stage or in the transitional stage from minerotrophic to ombrotrophic condition. In this study Hyalosphenia papilio was first recorded in China. It is a very typical species in Sphagnum peadand and frequently reported in other researches. Usually it presents in the relatively wetter habitats. However, another typical species in Sphagnum peadands, Amphitrema flavum, didn't occur in any samples. The species richness and Shannon - Weiner index varied gready among 75 samples. The maximum of species richness is 22, while the minimum is 3 and the average is 12.65. For Shannon -Weiner index, the maximum is 2.78, the minimum 0.72 and the average 1.93. The total of 33 taxa in 75 samples is less in comparison with other studies. This is probably because a relatively conservative identification guide was adopted in which some taxa were grouped as ' type ' in order that a more consistent and comparable result could be achieved among different observers.