Recent testate amoeba assemblages from the Kamchatka Peninsula (Russia)
Testate amoebae are a polyphyletic group of protists characterised by a shell (‘test’). Testate amoebae have been identified in a wide range of terrestrial, freshwater and coastal habitats but are most frequently-recorded in moist, organic-rich soils. The ecology of testate amoebae has been widely-investigated in contemporary ecosystems in order to develop species-environment (‘transfer function’) models to quantify the palaeoecological record with such studies undertaken in locations from Patagonia to Alaska and Britain to China. However, knowledge of testate amoeba diversity and ecology remains geographically-biased and large areas of the global land surface have yet to receive any study at all. Beyond the potential for unrecorded taxa in these regions, such data gaps impair attempts to use testate amoebae to understand patterns of protist biogeography and to interpret past assemblages in the palaeoecological record. However, testate amoeba assemblages of the remote Kamchatka Peninsula remain uninvestigated so far. The Kamchatka Peninsula is located in the far northeast of Eurasia, between the Sea of Okhotsk to the west and the North Pacific Ocean to the east (51-60°N, ~160°E). The data set addresses the following research questions: What are the key components of the Kamchatka testate amoeba fauna? Are there local or regional endemics? What are the key environmental controls on testate amoeba assemblage structure? Can testate amoebae provide reliable palaeohydrological proxies in Kamchatka peatlands?
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Two campaigns of field sampling were conducted. In summer 2007, 18 sites were sampled from across Kamchatka. Samples were extracted (typically one per site) from a range of vegetation types including forests, meadows and wetlands from both peat and mineral soils. Mineral soil samples represented 1-2 cm of litter or grass tussocks and 1cm of humus horizon; peat soils represented upper 3-5 cm of Sphagnum stems. In summer 2016, 37 samples were extracted from 16 individual peatlands in the West Kamchatka Lowland and through the central depression. 1-4 samples were extracted per site, aiming to span the microtopographic gradient. In both these sampling campaigns site selection aimed to span the range of testate amoeba habitats, however, given the remoteness of the region, the selection was also necessarily opportunistic and constrained by logistical considerations. In summer 2016 an intensive sampling campaign was also undertaken at one blanket bog site in West Kamchatka: Kiumshichek. Twenty samples were extracted along N-S and E-W transects across the peatland and a 40 cm core was extracted from the centre of the site. In the laboratory, samples were prepared for analysis of testate amoebae using a method based on suspension in water, physical agitation and sedimentation (Mazei & Chernyshov 2011). Samples were mounted in glycerol and analysed at 400x magnification using a light microscope.