The Microbial Loop at the Surface of a Peatland:Structure, Function, and Impact of Nutrient Input

Gilbert, Daniel; Amblard, Christian; Bourdier, Gilles; Francez, André-Jean

doi:10.1007/s002489900062

Cited by 200 publications

(197 citation statements)

References 25 publications

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“…The bacteria were counted in 250 randomly chosen fields of view. Biovolumes of the microbial community were estimated assuming geometric shapes and converting to carbon using the following conversion factor (Gilbert et al, 1998). Each sample of HNF was fixed in situ with formalin (a final concentration of 2%).…”

Section: Methodsmentioning

confidence: 99%

Indirect effect of environmental factors on interactions between microbial and classical food webs in freshwater ecosystems

Adamczuk

Mieczan

Nawrot

et al. 2015

Ann. Limnol. - Int. J. Lim.

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-The role of environmental factors in aquatic ecosystems results from basic lake characteristics, human disturbances ('cultural eutrophication') and climate-related trends in the physical and chemical components of lakes. Although the influence of environmental factors on the abundance of aquatic animals is fairly well documented, less has been done to research their influence on food web interactions. The aim of the study was to evaluate microbial and classical food webs in lakes, with special emphasis placed on the role of environmental factors as influencing strengths. Variation partitioning, based on redundancy analysis, revealed that environmental factors played the most important role in structuring aquatic communities by accounting for 87.5% of their variation. Among all the factors measured, total solids (TS), transparency (Secchi disc) and temperature were most closely related to the variation in trophic communities. The analyses of food web interactions under low and high levels of those factors revealed that they differently influenced strengths among food web components. The strongest relations among distinct trophic levels were found under conditions of low TS, the lowest number of relations was found under conditions of low temperature. Only in low TS did bacteria correlate significantly with biogenes. Under high TS, bacteria positively influenced plenty of higher trophic levels. Top-down control was observed under conditions of high temperature. Conditions of low and high transparency did not diversify food web interactions. The obtained results can broaden our knowledge of the response of food webs to environmental factors in advanced stages of global eutrophication of water bodies and in the early stage of projected trends of global climate change.

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Section: Methodsmentioning

confidence: 99%

Indirect effect of environmental factors on interactions between microbial and classical food webs in freshwater ecosystems

Adamczuk

Mieczan

Nawrot

et al. 2015

Ann. Limnol. - Int. J. Lim.

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“…Arcellinid testate amoebae are common and diverse in peatlands, where they constitute a large part (typically 10-30%) of microbial biomass (Gilbert, 1998;Gilbert et al, 1998;Mitchell et al, 2003). Their sensitivity to environmental changes and the good preservation of their shells in peat has led to their use as indicators of past environmental * Corresponding author.…”

Section: Introductionmentioning

confidence: 99%

Eight species in the Nebela collaris complex: Nebela gimlii (Arcellinida, Hyalospheniidae), a new species described from a Swiss raised bog

Kosakyan

Pillonel

Mitchell

et al. 2015

European Journal of Protistology

609

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We describe here a new species of sphagnicolous testate amoeba found abundantly in the forested part of the Le Cachot peatland (Jura Mountains, Neuchâtel, Switzerland) based on microscopical observations (LM, SEM). The new species, called Nebela gimlii was placed in a phylogenetic tree based on mitochondrial cytochrome oxidase sequences (COI), and branched robustly within the N. collaris complex next to the morphologically similar N. guttata and N. tincta. It is however genetically clearly distinct from these two species, and differs morphologically from them by its smaller size and stouter shape of the shell. This new species completes the phylogeny of the Nebela collaris species complex, with now eight species described, mostly from peatlands and acidic forest litter, and further demonstrates the existence of an unknown diversity within testate amoebae. Improving the taxonomy of testate amoebae in peatlands and clarifying the ecology of newly discovered species should make these organisms even more valuable as bioindicators and for palaeoecological reconstruction.

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“…Testate amoebae are an important component in the soil microbial food web. Together with other protozoans, testate amoebae are believed to regulate bacterial populations [31] and to play a role in nutrient mineralization and plant growth [29]. Some species are mixotrophic and contain endosymbiotic algae [63].…”

Section: Introductionmentioning

confidence: 99%

The Ecology of Testate Amoebae (Protists) in Sphagnum in North-western Poland in Relation to Peatland Ecology

2005

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We studied the relationship between testate amoebae (Protozoa) communities and the depth to the water table (DWT), pH, conductivity, and microhabitat type in Sphagnum dominated peatlands of north-western Poland and built predictive (transfer function) models for inferring DWT and pH based on the testate amoebae community structure. Such models can be used for peatland monitoring and paleoecology. A total of 52 testate amoebae taxa were recorded. In a redundancy analysis, DWT and pH explained 20.1% of the variation in the species data and allowed us to identify three groups of taxa: species that are associated with (1) high DWT and low pH, (2) low DWT and low pH, and (3) high pH and mid-range DWT. Our transfer function models allow DWT and pH to be estimated with mean errors of 9.89 cm and 0.71 pH units. The prediction error of the DWT model and the tolerance of the species both increase with increasing dryness. This pattern mirrors the ecology of Sphagnum mosses: Species growing in wet habitats are more sensitive to change in water table depth than the species growing in drier microhabitats. Our results are consistent with studies of testate amoeba ecology in other regions, and they provide additional support for the use of these organisms in paleoecological and biomonitoring contexts. IntroductionTestate amoebae are unicellular organisms living in a variety of habitats including lakes and mires [3,32,65]. Sphagnum peatlands are characterized by a high diversity of microhabitats in which many testate amoebae species occur. Testate amoebae produce shells (tests) that can be proteinaceous, pseudochitinous, or agglutinated with one or two pseudostome(s) and are diagnostic for identification [70,77]. Testate amoebae are an important component in the soil microbial food web. Together with other protozoans, testate amoebae are believed to regulate bacterial populations [31] and to play a role in nutrient mineralization and plant growth [29]. Some species are mixotrophic and contain endosymbiotic algae [63].Many species have well-defined ecological preferences, and this stenotopy makes them very useful bioindicators [30,47]. Previous studies have shown that the abundance of each taxon and hence the structure of communities are controlled by a set of environmental variables. Water availability (moisture or water table depth) was often identified as being the single most important factor controlling testate amoebae community composition on peatlands, the second most important variable usually being pH [4-6, 10-12, 15, 21, 45, 46, 48, 49, 71, 76]. The correlation between testate amoebae communities and moisture conditions is increasingly used to infer palaeohydrological changes in peatlands and, in the case of ombrotrophic peatlands, these data are ultimately used to infer past climate changes [13, 16-19, 35, 44, 79]. In addition to paleoecology, testate amoebae research can be applied to environmental monitoring of natural ecosystems and those affected by human activities. Examples include the monitoring of lak...

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The Microbial Loop at the Surface of a Peatland:Structure, Function, and Impact of Nutrient Input

Cited by 200 publications

References 25 publications

Indirect effect of environmental factors on interactions between microbial and classical food webs in freshwater ecosystems

Indirect effect of environmental factors on interactions between microbial and classical food webs in freshwater ecosystems

Eight species in the Nebela collaris complex: Nebela gimlii (Arcellinida, Hyalospheniidae), a new species described from a Swiss raised bog

The Ecology of Testate Amoebae (Protists) in Sphagnum in North-western Poland in Relation to Peatland Ecology

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