Fine-Scale Horizontal and Vertical Micro-distribution Patterns of Testate Amoebae Along a Narrow Fen/Bog Gradient

Abstract

The ecology of peatland testate amoebae is well studied along broad gradient from very wet (pool) to dry (hummock) micro-sites where testate amoebae are often found to respond primarily to the depth to water table (DWT). Much less is known on their responses to finerscale gradients, and nothing is known of their possible response to phenolic compounds, which play a key role in carbon storage in peatlands. We studied the vertical (0-3, 3-6, and 6-9 cm sampling depths) micro-distribution patterns of testate amoebae in the same microhabitat (Sphagnum fallax lawn) along a narrow ecological gradient between a poor fen with an almost flat and homogeneous Sphagnum carpet (fen) and a "young bog" (bog) with more marked micro-topography and mosaic of poor fen and bog vegetation. We analyzed the relationships between the testate amoeba data and three sets of variables (1) "chemical" (pH, Eh potential, and conductivity), (2) "physical" (water temperature, altitude, i.e., Sphagnum mat micro-topography, and DWT), and (3) phenolic compounds in/from Sphagnum (water-soluble and primarily bound phenolics) as well as the habitat (fen/bog) and the sampling depth. Testate amoeba Shannon H′ diversity, equitability J of communities, and total density peaked in lower parts of Sphagnum, but the patterns differed between the fen and bog micro-sites. Redundancy analyses revealed that testate amoeba communities differed significantly in relation to Eh, conductivity, water temperature, altitude, water-soluble phenolics, habitat, and sampling depth, but not to DWT, pH, or primarily bound phenolics. The sensitivity of testate amoebae to weak environmental gradients makes them particularly good integrators of micro-environmental variations and has implications for their use in paleoecology and environmental monitoring. The correlation between testate amoeba communities and the concentration of water-soluble phenolic suggests direct (e.g., physiological) and/or indirect (e.g., through impact on prey organisms) effects on testate amoebae, which requires further research.

Diurnal dynamics of the microbial loop in peatlands: structure, function and relationship to environmental parameters

“…It was observed in this study that among Utricularia and Calliergonella the concentrations of TOC and total phosphorus were several times higher, which could influence the abundance of food. The species communities for the peat bogs of Eastern Poland show a reasonable similarity with the results of other quantitative and qualitative studies of protists' ecology, in the peat bogs of other regions (Jassey et al, 2010, Lamentowicz et al, 2010. Protist communities demonstrated an evident correlation with the concentration of TOC and total phosphorus.…”

“…Such relations on other types of peatlands have not been studied so far. Until recently, only a few studies discussed the ecology of testate amoebae in fens (Payne & Mitchell, 2007;Jassey et al, 2010;Lamentowicz et al, 2010;Payne, 2011). The fact that peatland ecosystems are distinguished by a low concentration of nutrients and the highest concentrations of organic matter indicates the key role of the microbial loop in their functioning.…”

Re-assessing the vertical distribution of testate amoeba communities in surface peats: Implications for palaeohydrological studies

“…However, there is a limited understanding of the vertical distribution of encysted testate amoebae and the potential factors controlling this state, as encysted species have typically not been distinguished from live or dead individuals in most modern (i.e. surficial peat) and palaeoecological studies (Vincke et al 2004;Jassey et al 2011). Encystment is nevertheless considered to be a response to unfavourable environmental conditions such as desiccation (Lousier 1974;Woodland et al 1998;Booth and Zymunt 2005), frost (Mitchell et al 2000;Warner et al 2007) or decreases in food availability (Laminger 1984).…”

Environmental DNA COI barcoding for quantitative analysis of protists communities: A test using the Nebela collaris complex (Amoebozoa; Arcellinida; Hyalospheniidae)

“…To understand the ecological roles played by species quantitative estimates of their abundance and biomass are required. For soil protozoan groups such as ciliates and testate amoebae, this is currently done using highly time-consuming direct counting of known taxa (Foissner et al 2002;Jassey et al 2010;Payne and Mitchell 2009;Schwarz and Frenzel 2003) rather than environmental DNA approaches.…”