Ecology of testate amoebae in a North Carolina pocosin and their potential use as environmental and paleoenvironmental indicators

Booth, Robert K.; Sullivan, Maura E.; Sousa, Valerie A.

doi:10.2980/15-2-3111

Cited by 43 publications

(32 citation statements)

References 37 publications

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“…Indeed in the "fen" habitat, A. flavum, H. sphagni, and H. papilio were found in greatest abundance and marked the ecological transition in Sphagnum upper segments. These species are typically found in habitats with high (>95%) soil water content [7,30,63]. Other species such as N. tincta and A. muscorum described as xerophilous [12,13] were more abundant in the "bog" habitat.…”

Section: Species-environment Correlationsmentioning

confidence: 99%

“…However other factors, including altitude, temperature, Eh, conductivity, and free phenolics did explain a high proportion of the species data and all of these were significantly different or nearly so between the two areas. Thus although DWT almost always emerges as the strongest variable explaining testate amoeba community structure in Sphagnum peatlands [3,7], other variables become more important when the DWT gradient is short. Direct gradient analysis (RDA) with single explanatory variables revealed the correlations of chemical factors (i.e., Eh and conductivity) with testate amoeba communities in upper and intermediate segments.…”

Section: Species-environment Correlationsmentioning

confidence: 99%

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

et al. 2010

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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.

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Section: Species-environment Correlationsmentioning

confidence: 99%

Section: Species-environment Correlationsmentioning

confidence: 99%

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

et al. 2010

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“…Data filtering (outlier sample removal), although criticised, is often used in paleoecology (Woodland et al, 1998;Wilmshurst et al, 2003;Edwards et al, 2004;Booth et al, 2008). The rationale for this is that some sampled locations may correspond to unusual situations (e.g., affected by a confounding factor such as faeces/urine), so that their removal results in improved model performance.…”

Section: Lamentowiczmentioning

confidence: 99%

The performance of single- and multi-proxy transfer functions (testate amoebae, bryophytes, vascular plants) for reconstructing mire surface wetness and pH

et al. 2013

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Peatlands are widely exploited archives of paleoenvironmental change. We developed and compared multiple transfer functions to infer peatland depth to the water table (DWT) and pH based on testate amoeba (percentages, or presence/absence), bryophyte presence/absence, and vascular plant presence/absence data from sub-alpine peatlands in the SE Swiss Alps in order to 1) compare the performance of single-proxy vs. multi-proxy models and 2) assess the performance of presence/absence models. Bootstrapping cross-validation showing the best performing single-proxy transfer functions for both DWT and pH were those based on bryophytes. The best performing transfer functions overall for DWT were those based on combined testate amoebae percentages, bryophytes and vascular plants; and, for pH, those based on testate amoebae and bryophytes. The comparison of DWT and pH inferred from testate amoeba percentages and presence/absence data showed similar general patterns but differences in the magnitude and timing of some shifts. These results show new directions for paleoenvironmental research, 1) suggesting that it is possible to build good-performing transfer functions using presence/absence data, although with some loss of accuracy, and 2) supporting the idea that multi-proxy inference models may improve paleoecological reconstruction. The performance of multi-proxy and single-proxy transfer functions should be further compared in paleoecological data.

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“…Species com-monly described as omnivores probably occupy a different trophic level in the microbial network than specific feeders such as bacterivores or predators. Furthermore, many pigmented (photosynthetic) microorganisms are known or suspected to be mixotrophic (i.e., organisms that combine autotrophy and heterotrophy using endosymbiotic zoochlorellae); these include several testate amoeba species such as Hyalosphenia papilio and Archerella flavum [31,32], species that are commonly foundinnorthern Sphagnum peatlands (e.g., [18,[33][34][35][36]). The mixotrophic life trait has significant functional and physi-ological implications [10,37,38] and should theoretically translate into distinct isotopic ratios.…”

Section: Introductionmentioning

confidence: 99%

To What Extent Do Food Preferences Explain the Trophic Position of Heterotrophic and Mixotrophic Microbial Consumers in a Sphagnum Peatland?

et al. 2013

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Although microorganisms are the primary drivers of biogeochemical cycles, the structure and functioning of microbial food webs are poorly studied. This is the case in Sphagnum peatlands, where microbial communities play a key role in the global carbon cycle. Here, we explored the structure of the microbial food web from a Sphagnum peatland by analyzing (1) the density and biomass of different microbial functional groups, (2) the natural stable isotope (δ 13 C and δ 15 N) signatures of key microbial consumers (testate amoebae), and (3) the digestive vacuole contents of Hyalosphenia papilio, the dominant testate amoeba species in our system. Our results showed that the feeding type of testate amoeba species (bacterivory, algivory, or both) translates into their trophic position as assessed by isotopic signatures. Our study further demonstrates, for H. papilio, the energetic benefits of mixotrophy when the density of its preferential prey is low. Overall, our results show that testate amoebae occupy different trophic levels within the microbial food web, depending on their feeding behavior, the density of their food resources, and their metabolism (i.e., mixotrophy vs. heterotrophy). Combined analyses of predation, community structure, and stable isotopes now allow the structure of microbial food webs to be more completely described, which should lead to improved models of microbial community function.

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Ecology of testate amoebae in a North Carolina pocosin and their potential use as environmental and paleoenvironmental indicators

Cited by 43 publications

References 37 publications

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

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

The performance of single- and multi-proxy transfer functions (testate amoebae, bryophytes, vascular plants) for reconstructing mire surface wetness and pH

To What Extent Do Food Preferences Explain the Trophic Position of Heterotrophic and Mixotrophic Microbial Consumers in a Sphagnum Peatland?

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