Microscopy- or DNA-based analyses: Which methodology gives a truer picture of stream-dwelling decomposer fungal diversity?

Fernandes, Isabel Rodrigues; Pereira, Ana Sofia; Trabulo, José; Pascoal, Cláudia; Cássio, Fernanda; Duarte, Sofia Alexandra Ferreira

doi:10.1016/j.funeco.2015.08.005

Cited by 16 publications

(10 citation statements)

References 24 publications

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“…On the other hand, in Couros, fungal assemblages were dominated by D. foliicola that is reported to be abundant in nutrient-enriched (Gulis and Suberkropp 2003) and eutrophic streams (Pascoal et al 2005b;Duarte et al 2008Duarte et al , 2009. In this eutrophic stream, fungal diversity on leaves appeared to be higher when assessed by DNA-based techniques (data not shown), which is consistent with that found in other streams Fernandes et al 2015). Thus, DGGE was proven to be a useful technique to assess the diversity of fungi associated with leaves decomposing in hypertrophic streams, where sporulation was strongly inhibited.…”

Section: Discussionsupporting

confidence: 88%

Spring stimulates leaf decomposition in moderately eutrophic streams

et al. 2016

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In forested headwater streams, decomposition of allochthonous organic matter is a fundamental process driven by aquatic microbes and invertebrate shredders. We examined how season and eutrophication affect leaf decomposition and the associated decomposer communities by immersing leaves of a late deciduous species (Quercus robur) in five streams in Portugal along a gradient of eutrophication in autumn and spring. We found hump-shaped relationships between leaf decomposition and total nitrogen and phosphorus in stream water in both seasons. Leaf decomposition and shredder biomass were higher during spring in streams with moderate levels of eutrophication. Fungal sporulation and biomass were stimulated at moderate levels of eutrophication and inhibited at low or high levels of eutrophication. Fungal assemblage composition shifted between seasons and along the gradient of eutrophication. Tricladium chaetocladium increased its contribution to total conidial production in spring, while Dimorphospora foliicola was dominant in the most eutrophic streams where Articulospora tetracladia was almost absent. Invertebrate shredders were the primary decomposers of leaves in streams with moderate levels of eutrophication, particularly in the warmest season. Although the presence of late deciduous plant species, such as oak, in the riparian corridors may help to mitigate food depletion to freshwater decomposers in spring, our results suggest that moderate eutrophication can accelerate decomposition further reducing litter standing stocks in the warmer seasons.

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Section: Discussionsupporting

confidence: 88%

Spring stimulates leaf decomposition in moderately eutrophic streams

et al. 2016

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“…4, 5). Previous reports pointed to a strong influence of the trophic status in structuring microbial decomposer communities in streams (Pascoal et al, 2005a,b;Castela et al, 2008;Bärlocher et al, 2010;Geraldes, 2011;Fernandes et al, 2015;Pereira et al, 2016) or pH (Wood-Eggenschwiler & Bärlocher, 1983;Bärlocher, 1987;Baudoin et al, 2008), within the same climatic zone. But, at a larger extent, climate has been pointed as a primary predictive factor in structuring fungal decomposer communities in streams, evidenced by the higher similarity shared between distant tropical locations (e.g.…”

Section: Discussionmentioning

confidence: 95%

“…Jabiol et al, 2013), incorporating a larger number of streams in different latitudinal bands and along larger environmental gradients, to better assess the relative importance of environmental and geographical factors in structuring fungal communities in streams. Identical methods to assess diversity should be used, and although much of the current knowledge on aquatic hyphomycete distribution patterns have been acquired based on the identification of morphospecies, we suggest that high throughput sequencing techniques should be employed due to its higher sensitivity and degree of differentiation between communities (Heino et al, 2014;Fernandes et al, 2015).…”

Section: Discussionmentioning

confidence: 99%

Environmental drivers are more important for structuring fungal decomposer communities than the geographic distance between streams

Duarte¹,

Cássio²,

Pascoal³

2017

Limnetica

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Environmental drivers are more important for structuring fungal decomposer communities than the geographic distance between streamsOne of the major challenges in microbial ecology is to unravel the mechanisms that operate at the spatial-temporal scales structuring microbial communities and how these communities respond to environmental change. It has been argued that the biogeography of microorganisms solely reflects the influence of contemporary environmental variation and "everything is everywhere". Since the discovery of the key role that decomposer fungi, in particular aquatic hyphomycetes, play in leaf-litter decomposition in streams, mycologists were interested in deciphering several ecological aspects, including the factors that shape the distribution of these communities in streams. At local and regional scales, community structure is affected by several abiotic factors such as pH, temperature, conductivity and nutrients in the stream water, but at a global scale, community similarity also decreases as a function of the geographic distance. However, very few attempts have been conducted to assess the relative influence of environmental versus geographic factors in structuring decomposer fungi in streams. In the current study, we attempted to fulfil this lacuna by quantifying the relative contributions of environmental factors versus spatial factors to community composition, by using data of species composition and environmental (temperature, pH, conductivity and nutrient concentrations) and spatial variables (latitude, longitude and altitude), collected during a recent extensive literature search. Alfa diversity was negatively affected by pH, conductivity, nitrates and phosphorus concentrations in the stream water. On the other hand, a unimodal type relationship was found between species richness and temperature, latitude or altitude. Beta-diversity was also strongly influenced by environmental factors, in particular conductivity, nitrates and phosphorus concentrations, and pH in stream water, but also by the geographic location (latitude and longitude) of the study sites. However, when the effects were disentangled a significant effect was found only for environmental variables. This suggests that streamdwelling decomposer fungi may exhibit biogeographic patterns, but as proposed by Baas-Becking "the environment selects" and is in part responsible for the spatial variation of stream-dwelling decomposer fungi. However, our conclusions should be taken cautiously because our data were extracted from the literature and reflect a geographical bias in the collection effort. Thus, future investigations should involve broad-scale coordinated surveys, incorporating a larger number of streams in different latitudinal bands and along large environmental gradients, to better assess the relative importance of environmental and geographical factors in structuring fungal communities in streams.

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“…ITS1-F primer has been reported to discriminate well fungal against plant DNA [ 39 ]. Although in previous studies we have targeted ITS2 region in NGS [ 31 , 40 ], we got some contamination with non-fungal DNA [ 31 ], and in this study we wanted to avoid that.…”

Section: Methodsmentioning

confidence: 99%

Taxa-area relationship of aquatic fungi on deciduous leaves

et al. 2017

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One of the fundamental patterns in macroecology is the increase in the number of observed taxa with size of sampled area. For microbes, the shape of this relationship remains less clear. The current study assessed the diversity of aquatic fungi, by the traditional approach based on conidial morphology (captures reproducing aquatic hyphomycetes) and next generation sequencing (NGS; captures other fungi as well), on graded sizes of alder leaves (0.6 to 13.6 cm2). Leaves were submerged in two streams in geographically distant locations: the Oliveira Stream in Portugal and the Boss Brook in Canada. Decay rates of alder leaves and fungal sporulation rates did not differ between streams. Fungal biomass was higher in Boss Brook than in Oliveira Stream, and in both streams almost 100% of the reads belonged to active fungal taxa. In general, larger leaf areas tended to harbour more fungi, but these findings were not consistent between techniques. Morphospecies-based diversity increased with leaf area in Boss Brook, but not in Oliveira Stream; metabarcoding data showed an opposite trend. The higher resolution of metabarcoding resulted in steeper taxa-accumulation curves than morphospecies-based assessments (fungal conidia morphology). Fungal communities assessed by metabarcoding were spatially structured by leaf area in both streams. Metabarcoding promises greater resolution to assess biodiversity patterns in aquatic fungi and may be more accurate for assessing taxa-area relationships and local to global diversity ratios.

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Microscopy- or DNA-based analyses: Which methodology gives a truer picture of stream-dwelling decomposer fungal diversity?

Cited by 16 publications

References 24 publications

Spring stimulates leaf decomposition in moderately eutrophic streams

Spring stimulates leaf decomposition in moderately eutrophic streams

Environmental drivers are more important for structuring fungal decomposer communities than the geographic distance between streams

Taxa-area relationship of aquatic fungi on deciduous leaves

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