Testate amoebae as predators of nematodes

Yeates, G. W.; Foissner, Wilhelm

doi:10.1007/bf00307834

Cited by 63 publications

(32 citation statements)

References 13 publications

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“…This apparent negative effect of dry conditions on bacteria density and production parallels the pattern of testate amoeba density where low numbers were found in the more advanced, drier secondary sites and in the unexploited site. Testate amoebae feed on a broad range of micro‐organisms, thus the lower density of testate amoebae in the drier sites matches the density patterns of at least some of their prey (the bacteria) and microbial secondary production (Yeates & Foissner 1995; Gilbert et al . 2000).…”

Section: Discussionmentioning

confidence: 92%

Cut‐over peatland regeneration assessment using organic matter and microbial indicators (bacteria and testate amoebae)

Laggoun‐Défarge

Mitchell²,

Gilbert

et al. 2007

Journal of Applied Ecology

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Summary 1.Cut-over peatlands cover large surfaces of high potential value for enhancing biodiversity and carbon sequestration if successfully restored. Unfortunately, evaluation of restoration success is not straightforward. We assessed the bioindicator value of organic matter (OM), testate amoebae (protozoa) and bacteria in peat from two regeneration stages and a reference site of a cut-over bog. 2. Contrasting biochemical signatures of peat OM were observed along the regenerating profiles, allowing clear differentiation between the newly regenerated peat and the old peat. Where peat macrofossils were absent sugar biomarkers were used to infer peat botanical origin and OM alteration. 3. Over the succession, the OM composition of the new peat differed. Peat from the more recent stage was dominated by Sphagnum -derived tissues and characterized by lower carbohydrate preservation and higher bacterial biomass than the advanced regeneration stage. 4. Surface testate amoeba communities also changed from the recent to the advanced stages of regeneration, indicating a shift from wet and moderately acidic conditions to drier and more acidic conditions. Over this regeneration sequence (i) the biomass and average size of species declined but were higher at the unexploited site and (ii) species richness and diversity increased but density declined. Synthesis and applications.Although secondary succession in the cut-over bog led to an ecosystem similar to that of the reference site in terms of surface vegetation, OM and testate amoebae continued to reflect disturbances associated with peat harvesting. Nevertheless, the described dynamics of both microbial and biochemical variables over the succession showed similarities between the advanced stage and the reference site: a higher testate amoeba diversity was associated with better carbohydrate preservation and a more heterogeneous botanical composition of the peat. The inferred water table depth and pH based on testate amoebae indicators proved to be an alternative approach for assessing restoration processes, in contrast to labour-intensive repeated measurements in the field. The botanical and biochemical composition of peat OM provided additional information on past anthropogenic perturbations of the bog and could be used for restoration monitoring. The combination of several indicators therefore provides a more complete assessment of ecological conditions that could be valuable for the management of cut-over peatlands.

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Section: Discussionmentioning

confidence: 92%

Cut‐over peatland regeneration assessment using organic matter and microbial indicators (bacteria and testate amoebae)

Laggoun‐Défarge

Mitchell²,

Gilbert

et al. 2007

Journal of Applied Ecology

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“…3C, F). Testate amoebae prey on a large spectrum of organisms (bacteria cyanobacteria, algae, protozoa, rotifers, and nematodes) [47], and Pb contamination decreased the density of several of these. This effect could have restricted the choice of prey for testate amoebae, and decreased their density.…”

Section: Potential Trophic Effectsmentioning

confidence: 99%

Effects of Experimental Lead Pollution on the Microbial Communities Associated with Sphagnum fallax (Bryophyta)

et al. 2007

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Ecotoxicological studies usually focus on single microbial species under controlled conditions. As a result, little is known about the responses of different microbial functional groups or individual species to stresses. In an aim to assess the response of complex microbial communities to pollution in their natural habitat, we studied the effect of a simulated lead pollution on the microbial community (bacteria, cyanobacteria, protists, fungi, and micrometazoa) living on Sphagnum fallax. Mosses were grown in the laboratory with 0 (control), 625, and 2,500 mg L _ 1 of Pb 2+ diluted in a standard nutrient solution and were sampled after 0, 6, 12, and 20 weeks. The biomasses of bacteria, microalgae, testate amoebae, and ciliates were dramatically and significantly decreased in both Pb addition treatments after 6, 12, and 20 weeks in comparison with the control. The biomass of cyanobacteria declined after 6 and 12 weeks in the highest Pb treatment. The biomasses of fungi, rotifers, and nematodes decreased along the duration of the experiment but were not significantly affected by lead addition. Consequently, the total microbial biomass was lower for both Pb addition treatments after 12 and 20 weeks than in the controls. The community structure was strongly modified due to changes in the densities of testate amoebae and ciliates, whereas the relative contribution of bacteria to the microbial biomass was stable. Differences in responses among the microbial groups suggest changes in the trophic links among them. The correlation between the biomass of bacteria and that of ciliates or testate amoebae increased with increasing Pb loading. We interpret this result as an effect on the grazing pathways of these predators and by the Pb effect on other potential prey (i.e., smaller protists). The community approach used here complements classical ecotoxicological studies by providing clues to the complex effect of pollutant-affecting organisms both directly and indirectly through trophic effects and could potentially find applications for pollution monitoring.

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“…Gilbert et al () suggest that testate amoebae may be of high significance in controlling the number of bacteria in the environment of Sphagnum mosses on ombrotrophic peatlands. Yeates and Foissner () suggested that some testate amoebae could even feed on large predatory nematodes. Until recently, only a few studies discussed the trophic position of testate amoebae in peatbogs, even for dominant species (Jassey et al, , ).…”

Section: Introductionmentioning

confidence: 99%

Stable isotope analyses revealed high seasonal dynamics in the food web structure of a peatbog

Mieczan

Niedźwiecki

Adamczuk

et al. 2015

Internat. Rev. Hydrobiol.

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Stable isotope analysis has become a powerful tool for the study of food web structures in aquatic communities. However, there has been little recognition of the spatial and temporal variabilities of isotopes in food webs in peatbogs. Here, we investigated the structure of food web in peatbog dominated by Sphagnum mosses by analyzing: (i) density and biomass of different components of food webs; (ii) the digestive vacuole contents of Hyalosphenia papilio—the most abundant species of amoebae occurring in peatbog; (iii) the seasonal changes in the carbon and nitrogen stable isotope signatures of particular components of food web. The study was performed in the Moszne peatbog located in the western part of Polesie Lubelskie (eastern Poland). Fieldwork was done on a monthly basis from April to November 2013. The largest total biomass of microorganisms in all of the seasons was noted in testate amoebae. Algae and cyanobacteria were the second largest group of microorganisms. The feeding behaviour of H. papilio varied throughout season. Among the identified prey, the highest frequency was noted in algae, cyanobacteria and ciliates. In spring and summer, prey was dominated by phycoflora, while during the autumn period the main prey consisted of cyanobacteria and ciliates. The results of the study indicate significant seasonal variation in the level of stable isotopes in individual components (bacteria, fungi, protozoa and metazoa) of the food web of peatbog, and thus also considerable dynamics of changes between trophic levels.

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Testate amoebae as predators of nematodes

Cited by 63 publications

References 13 publications

Cut‐over peatland regeneration assessment using organic matter and microbial indicators (bacteria and testate amoebae)

Cut‐over peatland regeneration assessment using organic matter and microbial indicators (bacteria and testate amoebae)

Effects of Experimental Lead Pollution on the Microbial Communities Associated with Sphagnum fallax (Bryophyta)

Stable isotope analyses revealed high seasonal dynamics in the food web structure of a peatbog

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