Earth and Environmental Sciences, Lehigh University, 1 West Packer Avenue, Bethlehem, PA 18015-3001, USA.
Microb Ecol. 2011 Jul;62(1):80-93. doi: 10.1007/s00248-011-9875-y. Epub 2011 May 31.
Testate amoebae are a group of moisture-sensitive, shell-producing protozoa that have been widely used as indicators of changes in mean water-table depth within oligotrophic peatlands. However, short-term environmental variability (i.e., sub-annual) also probably influences community composition. The objective of this study was to assess the potential influence of short-term environmental variability on the composition of testate amoeba communities in Sphagnum-dominated peatlands. Testate amoebae and environmental conditions, including hourly measurements of relative humidity within the upper centimeter of the peatland surface, were examined throughout the 2008 growing season at 72 microsites within 11 peatlands of Pennsylvania and Wisconsin, USA. Relationships among testate amoeba communities, vegetation, depth to water table, pH, and an index of short-term environmental variability (EVI), were examined using nonmetric multidimensional scaling and correlation analysis. Results suggest that EVI influences testate amoeba communities, with some taxa more abundant under highly variable conditions (e.g., Arcella discoides, Difflugia pulex, and Hyalosphenia subflava) and others more abundant when environmental conditions at the peatland surface were relatively stable (e.g., Archerella flavum and Bullinularia indica). The magnitude of environmental variability experienced at the peatland surface appears to be primarily controlled by vegetation composition and density. In particular, sites with dense Sphagnum cover had lower EVI values than sites with loose-growing Sphagnum or vegetation dominated by vascular plants and/or non-Sphagnum bryophytes. Our results suggest that more environmental information may be inferred from testate amoebae than previously recognized. Knowledge of relationships between testate amoebae and short-term environmental variability should lead to more detailed and refined environmental inferences.
有壳的变形虫是一群对水分敏感、产壳的原生动物，已被广泛用作贫营养泥炭地中平均水位深度变化的指示物。然而，短期环境变化（即亚年度）也可能影响群落组成。本研究的目的是评估短期环境变化对主导泥炭地的有壳变形虫群落组成的潜在影响。在 2008 年生长季节，在美国宾夕法尼亚州和威斯康星州的 11 个泥炭地的 72 个微生境中，检查了有壳变形虫和环境条件，包括泥炭地表层 1 厘米内的相对湿度的每小时测量。使用非度量多维尺度分析和相关分析研究了有壳变形虫群落、植被、水位深度、pH 值和短期环境变异性指数 (EVI) 之间的关系。结果表明，EVI 影响有壳变形虫群落，一些分类群在高度可变的条件下更为丰富（例如，Arcella discoides、Difflugia pulex 和 Hyalosphenia subflava），而其他分类群在泥炭地表层环境相对稳定的条件下更为丰富（例如，Archerella flavum 和 Bullinularia indica）。泥炭地表层经历的环境变异性的幅度似乎主要受植被组成和密度控制。特别是，覆盖密集的泥炭藓的地点的 EVI 值低于生长松散的泥炭藓或由维管束植物和/或非泥炭藓苔藓植物主导的地点。我们的结果表明，有壳变形虫可能提供比以前认为的更多的环境信息。了解有壳变形虫与短期环境变化之间的关系应该会导致更详细和更精细的环境推断。
