A new local testate amoebae transfer function from northwest Siberian permafrost peatlands

Testate amoebae (TA) transfer functions have been used in palaeoecological studies for more than 30 years. Several widely used transfer functions are available; however, studies have shown that the performance of the transfer function declines if it is applied outside the area of its development. This observation and the increasing use of TA in research conducted on a wide range of peatlands in Asia have resulted in a recently constructed Asian data set. However, this continental-scale training set does not include data from newly collected Sphagnum-dominated northwest (NW) Siberian peatlands. Because of the presence of permafrost and ongoing thawing processes, this specific mosaic ecosystem creates unique living conditions for microorganisms (e.g., TA). Therefore, to decode the history of this area more accurately the local transfer function is needed. Our aim was to make a new local transfer function based on surface samples from peatland collected in the irregular permafrost area - Khanymey region (NW Siberia, Russia). A total of 76 surface samples were collected from location along microtopographic gradient of peatlands, including hummocks, hollows, lawns and pools. For TA analysis, the upper 5 cm of growth of Sphagnum spp., brown mosses, and Cladonia sp. were collected. During the sampling the DWT or permafrost (when water table was not present) was measured. The collected samples represented the moisture gradient from +38 cm (terrestrial habitat) to -20 cm (inundated surface) including the permafrost area. In each sample, 150 shells were counted. TA was identified using a consensus taxonomic framework, which led to the creation of a list of TA from NW Siberian permafrost peatlands. We also developed new local TA-based hydrological transfer functions using software C2. We noted that the occurrence and properties of the active layer creates significantly different moisture conditions for TA, leading to changes in TA composition. Contrastingly, some inundated habitats (including associated TA communities) might occur due to permafrost thawing as an effect of the global warming. We plan to use the new transfer function in the analysis of a core collected from the same area. The study was supported by the National Science Center (Grant no. 2019/35/O/ST10/0290) and INTERACT No. 730938 - PeatHOT project.