Species Of Aquatic Hyphomycetes Research Articles

Dual effects of drying and urban pollution on leaf litter decomposition and shredder consumption in permanent and intermittent streams

In the present study we investigated the combined effect of flow intermittence and wastewater treatment plant (WWTP) effluent on leaf litter decomposition in two Mediterranean streams with permanent and intermittent flow regimes. The litter decomposition experiment was performed using black poplar litter bags where we measured litter mass loss, fungal biomass, aquatic hyphomycete sporulation and species richness and C:N ratio. Afterwards, the remaining litter material from the different treatments was offered to the shredder Potamophylax latipennis in a microcosm laboratory experiment, and its growth and consumption rates were studied. We hypothesised that drying would decrease leaf litter decomposition in the permanent stream more than in the intermittent stream and that WWTP effluent would compensate for drying effects when both stressors interacted. The results indicated that drying has the greatest impact on the permanent stream, decreasing decomposition, aquatic hyphomycete species richness, and leaf litter quality. In the intermittent stream, WWTP effluent decreases aquatic hyphomycete species richness, but drying increases it, showing an opposing effect and a synergistic interaction. In the permanent stream drying provoked an increase in the shredder consumption rate. Thus, the expected more frequent intermittence in rivers under climate change may threaten the processing of organic matter.

ITS rDNA Barcodes Clarify Molecular Diversity of Aquatic Hyphomycetes.

Aquatic hyphomycetes are key microbial decomposers of allochthonous organic matter in freshwater ecosystems. Although their importance in carbon flow and food webs in streams is widely recognized, there are still gaps in our understanding of their molecular diversity and distribution patterns. Our study utilized the growing database of ITS rDNA barcodes of aquatic hyphomycetes (1252 sequences) and aimed to (i) produce new barcodes for some lesser-known taxa; (ii) clarify the taxonomic placement of some taxa at the class or order level, based on molecular data; and (iii) provide insights into the biogeographical origins of some taxa. This study increased the number of aquatic hyphomycete species with available ITS barcodes from 119 (out of ~300 species described) to 136. Phylogenetically, the 136 species were distributed between 2 phyla, 6 classes, and 10 orders of fungi. Future studies should strive to increase the database of ITS sequences, especially focusing on species with unclear phylogenetic relationships (incertae sedis) and with few sequences available. The geographical distribution of species with available ITS sequences included 50 countries from five continents, but 6 countries had more than 20 species associated, showing a bias toward the northern hemisphere, likely due to sampling bias.

Influence of environmental predictors on hyphomycete assemblages in subtropical streams

Hyphomycetes are important aquatic organisms for organic matter decomposition, releasing inorganic nutrients to the environment. Understanding distribution patterns of hyphomycetes among different types of habitats can reveal important environmental characteristics that affect their assemblages and, as a consequence, can change stream functioning. We evaluated the effects of environmental predictors over hyphomycete assemblages in a field experiment in 12 subtropical Atlantic Forest streams. We identified 21 species of aquatic hyphomycetes, where Lunulospora curvula, Flagellospora curvula and Aquanectria submersa are dominant species, occurring in 10 streams, while Anguillospora sp., Campylospora parvula and Mycocentrospora acerina were found in only one stream. The variables dissolved oxygen, electrical conductivity and pH-influenced hyphomycete assemblages. Electrical conductivity acts as filter for spore output, while dissolved oxygen, electrical conductivity and phosphate are environmental filters for species richness. Our findings highlight the importance of environmental predictors over aquatic hyphomycete assemblages. The influence of environmental predictors over spore output and species richness may change stream functioning, since these organisms play an important role in leaf breakdown.

A comparison of decomposition rates and biological colonization of leaf litter from tropical and temperate origins

Litter decomposition is an ecosystem process that allows energy and nutrients transfer from dead plant matter into detrital food webs. Several studies revealed that leaf litter decomposition rates differ across biomes, but the reasons for these differences are not yet clear. Here, we test the role of several leaf litter physical and chemical characteristics as predictors of decomposition rates and whether life forms (evergreen vs. deciduous) differ in decomposition rates. Leaves from dominant riparian trees were collected in four ecoregions (temperate deciduous forest, subtropical seasonal semideciduous forest, tropical Cerrado and subtropical dense ombrophylous forest) and their physical and chemical characteristics were measured. We then determined leaf litter decomposition, colonization by aquatic hyphomycetes and macroinvertebrates in a same stream (i.e., under the same environmental conditions), and consumption rates by shredders under laboratory conditions. Deciduous and evergreen tree species did not differ in the measured litter characteristics, but deciduous leaves decompose faster than evergreens. Leaf litter from tree species from the four ecoregions differed in their physical and chemical characteristics. Litter from temperate deciduous species decomposed faster than litter from the other three ecoregions, generally supported higher aquatic hyphomycete species richness and sporulation rates and higher consumption rates by shredders. There were significant negative correlations between litter decomposition and associated biotic variables and litter initial lignin concentration and lignin:N ratio. We conclude that lignin concentration and lignin:N ratio are important predictors of litter decomposition, although other unmeasured parameters such as micronutrients may also play important roles in this key ecosystem process.

Aquatic Hyphomycetes from streams on Madeira Island (Portugal).

BackgroundAquatic hyphomycetes are a phylogenetically heterogeneous group of fungi living preferentially in fast flowing, well-aerated forest streams. These fungi have worldwide distribution, but with the exception of Articulospora tetracladia, no aquatic hyphomycete taxon was previously recorded on Madeira Island. Aquatic hyphomycetes were sampled from 40 sites, distributed by 27 permanent streams in 2015, to provide the distribution of aquatic hyphomycetes in Madeira Island streams.New informationIn this study, a total of 21 species of aquatic hyphomycetes were recorded belonging to three classes of Ascomycota. All taxa are new records for Madeira Archipelago, except Articulospora tetracladia and four are reported for the first time in Macaronesian biogeographic region.

Inter- and intraspecific functional variability of aquatic fungal decomposers and freshwater ecosystem processes

Although considerable intraspecific trait variation is common, research dedicated to ecosystem functioning has focused mainly on species diversity. Organic matter breakdown, a key ecosystem-level process in woodland streams is mainly driven by aquatic hyphomycetes. These aquatic fungal decomposers constitute a critical link between plant litter and invertebrate detritivores in detritus-based food webs in streams. In this study, we evaluated the functional variability across a set of ten isolates each belonging to five widespread aquatic hyphomycete species, namely Articulospora tetracladia, Anguillospora crassa, Lemonniera terrestris, Neonectria lugdunensis and Tetracladium marchalianum. All the isolates originated from undisturbed streams. We estimated inter- and intraspecific variability on growth rates, litter decomposition and sporulation rates of the isolates. In addition, we also assessed the invertebrate consumption rates on leaves colonized by different isolates. Significant differences were observed within the fungal species in growth rates (A. crassa, L. terrestris, N. lugdunensis and T. marchalianum), leaf litter decomposition (A. tetracladia, L. terrestris and N. lugdunensis) and sporulation rates (A. crassa, A. tetracladia, L. terrestris and N. lugdunensis). The relative consumption rates of the shredder Schizopelex festiva significantly differed when fed with leaves colonized by isolates of L. terrestris and N. lugdunensis, however differences were not seen when fed with leaves conditioned by different species. Overall, results indicate substantial intraspecific functional variability among the isolates of aquatic hyphomycetes. Besides, our study also provides a novel insight that intraspecific functional variability is a natural phenomenon exhibited by isolates not only from polluted but also from undisturbed streams. Here the isolates demonstrated marked inter- and intraspecific functional variability, calling for a greater understanding of the functional role of aquatic hyphomycetes and its ability to influence higher trophic levels.

Aquatic Hyphomycetes of Kumaun Himalaya: Tricladium

Aquatic hyphomycetes are ecologically important, polyphyletic group of aquatic fungi with distinctly shaped conidia. Various running fresh water bodies of Kumaun Himalaya were surveyed and different submerged leaf litter, foam as well as roots of riparian plants were collected. Collected samples were processed, incubated and examined for the presence of aquatic hyphomycetes. Overall, eight species of aquatic hyphomycetes belonging to the genus Tricladium (T. aciculum, T. angulatum, T. anomalum, T. indicum, T. marylandicum, T. chaetocladium, T. splendens and T. terrestre) were recorded from submerged leaf litter and live roots of various riparian plants. Of these, T. marylandicum was new addition to the Indian mycoflora while two species T. indicum and T. marylandicum were recovered as root endophyte for the first time. A detailed taxonomic description including occurrence and distribution of each Kumaun Himalayan species of Tricladium is described and discussed here under.

Does nanosized plastic affect aquatic fungal litter decomposition?

Abstract Nanosized plastics are an emerging concern in freshwater ecosystems, raising the question whether they put freshwater ecological processes at risk. Litter decomposition is a major ecological function in forested streams which is mainly driven by aquatic hyphomycetes. Here we investigated whether increasing concentrations (up to 102.4 mg/L) of nanosized polystyrene plastics (NPPs; 100nm) affect litter decomposition by five widely distributed species of aquatic hyphomycetes. Results showed that average litter decomposition decreased by 8% relative to the control when exposed to 102.4 mg/L NPPs. Aquatic hyphomycete species differed in their sensitivity to NPPs. The greatest inhibition of litter decomposition was found with Tetracladium marchalianum, where it dropped from 37 (control) to 16% (102.4 mg/L of NPP). Overall our study highlights the emerging risks and potential dangers of NPPs to freshwater ecosystem functioning. It also indicates that the impact of NPPs may be species specific.

Rapid characterization of aquatic hyphomycetes by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

ABSTRACTProtein fingerprinting using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-­TOF MS) is a rapid, reliable, and economical method to characterize isolates of terrestrial fungi and other microorganisms. The objective of our study was to evaluate the suitability of MALDI-TOF MS for the identification of aquatic hyphomycetes, a polyphyletic group of fungi that play crucial roles in stream ecosystems. To this end, we used 34 isolates of 21 aquatic hyphomycete species whose identity was confirmed by spore morphology and internal transcribed spacer (ITS1-5.8S-ITS2 = ITS) nuc rDNA sequencing. We tested the efficiency of three protein extraction methods, including chemical and mechanical treatments using 13 different protocols, with the objective of producing high-quality MALDI-TOF mass spectra. In addition to extraction protocols, mycelium age was identified as a key parameter affecting protein extraction efficiency. The dendrogram based on mass-spectrum similarity indicated good and relevant taxonomic discrimination; the tree structure was comparable to that of the phylogram based on ITS sequences. Consequently, MALDI-TOF MS could reliably identify the isolates studied and provided greater taxonomic accuracy than classical morphological methods. MALDI-TOF MS seems suited for rapid characterization and identification of aquatic hyphomycete species.

Fungal systematics and evolution : FUSE 4

Eight new species presented are Calostoma areolatum collected in Wuyishan National Park (China), Crinipellis bidens from Hubei Province (China), Lactifluus sainii from Himalayan India, Inocybe elata from Yunnan (China), Inocybe himalayensis from Pakistan. Specimens previously identified as Massalongia carnosa represent a new species, namely M. patagonica restricted to southern South America. Saprolegnia maragheica is a new oomycete species of fresh water in Maraghe (Iran). Uncispora wuzhishanensis is a new aquatic hyphomycete species. A type specimen of Raddetes turkestanicus was studied and based on this the new combination Conocybe turkestanica, is proposed. Argyranthemum frutescens is a new host for Alternaria alternata and Syzygium cumini for Phyllosticta capitalensis in India. Crepidotus ehrendorferi is confirmed for Hungary and Pluteus leucoborealis for Central Europe, and for the phytogeographical region of Carpaticum. Pseudopithomyces palmicola is shown to occur on grapevine and it is validated by adding a unique identifier. Terfezia fanfani is reported first from Algeria.

Classiculasinensis, a new species of basidiomycetous aquatic hyphomycetes from southwest China.

Classiculasinensis, isolated from decaying leaves from Mozigou, Chongqing Municipality, China, is described as a new species. The new species is a member of basidiomycetous aquatic hyphomycetes which represent a small proportion of all aquatic hyphomycetes. This species falls within the genus Classicula (Classiculaceae, Pucciniomycotina) and is closely related to C.fluitans, based on multiple gene sequence analyses. Morphologically, it is characterised by the apical, hyaline, obclavate or navicular conidia with several hair-like lateral appendages and by its holoblastic and monoblastic conidiogenesis, with a flat un-thickened conidiogenous locus. Clamp connections and haustorial branches were often observed in culture.

Allelopathic inhibition of primary producer growth and photosynthesis by aquatic fungi

Autochthonous primary production is generally much reduced in forested headwater streams. Several hypotheses have been proposed for explaining this observation, among them, the low light intensity, or the strong constraints exerted by stream current. Allelopathic inhibition of competitors is a common ecological process in aquatic environments. Aquatic hyphomycetes are known to chemically inhibit bacteria and other fungi (including other aquatic hyphomycetes) but a possible allelopathic effect of aquatic hyphomycetes on primary producers has never been tested. The inhibitory effect of twelve aquatic hyphomycete species was tested on three diatom species. Nine aquatic hyphomycete species exhibited anti-diatom activity. Up to 100% diatom growth inhibition was observed. Our study reveals that such allelopathic interactions might be common in streams and probably involve an array of fungal compounds. We propose that the generally reduced primary production observed in forested headwater streams is, among other factors, due to the inhibition of primary producers by allelopathic compounds released by aquatic hyphomycetes.

Stream salinization and fungal-mediated leaf decomposition: A microcosm study

Salinization is of major global concern due to its effect on stream biota, and ecosystem functions and services. In small streams, litter decomposition is a key ecosystem-level process driven by decomposers, mainly fungi (aquatic hyphomycetes), which link litter and invertebrates. Here we assessed the effects of an environmentally relevant range of salt additions (0, 2, 4, 8, 16gL−1 NaCl) on (1) fungal growth and species-specific reproductive output and (2) fungal mediated-decomposition of Quercus robur leaves. Growth rates of eight out of nine species of aquatic hyphomycetes were negatively affected by salinity at concentrations ≥4gL−1. EC50s were species-specific and ≥7.80gL−1. Distinct thresholds were observed for reproduction: only five species sporulated at 2gL−1, and a single one (Flagellospora curta) sporulated at 4 and 8gL−1 NaCl. Based on these results, we evaluated if tolerant fungal assemblages, with increasingly fewer species (9, 5, 1), were able to maintain similar functional functions and processes at the different salt levels. No significant differences were found in oak mass loss or sporulation rates at 0 or 2gL−1 NaCl; a clear inhibition of both parameters was observed at the highest concentrations (i.e., 4 and 8gL−1 NaCl). Different dominance patterns in multi-species fungal assemblages may determine bottom-up impacts on the stream food webs through effects on detritivore feeding preferences. Specific growth rate, characterized by RNA concentration, was higher in the single species, at the highest salt-concentration, and lower in the 9-species assemblage. Respiration was almost 2-times higher in mixed assemblages without added salt. Under salt-contamination, trade-offs between growth and sporulation seem to guarantee high levels of fungal growth and decomposition, particularly in multi-species assemblages. In the presence of salt contamination, aquatic hyphomycetes, even at reduced diversity, remain important drivers of leaf decomposition and ensure organic matter recycling.

Quantitative real-time PCR as a promising tool for the detection and quantification of leaf-associated fungal species - A proof-of-concept using Alatospora pulchella.

Traditional methods to identify aquatic hyphomycetes rely on the morphology of released conidia, which can lead to misidentifications or underestimates of species richness due to convergent morphological evolution and the presence of non-sporulating mycelia. Molecular methods allow fungal identification irrespective of the presence of conidia or their morphology. As a proof-of-concept, we established a quantitative real-time polymerase chain reaction (qPCR) assay to accurately quantify the amount of DNA as a proxy for the biomass of an aquatic hyphomycete species (Alatospora pulchella). Our study showed discrimination even among genetically closely-related species, with a high sensitivity and a reliable quantification down to 9.9 fg DNA (3 PCR forming units; LoD) and 155.0 fg DNA (47 PCR forming units; LoQ), respectively. The assay’s specificity was validated for environmental samples that harboured diverse microbial communities and likely contained PCR-inhibiting substances. This makes qPCR a promising tool to gain deeper insights into the ecological roles of aquatic hyphomycetes and other microorganisms.

Nutrient enrichment and flow regulation impair structure and function of a large river as revealed by aquatic hyphomycete species richness, biomass, and decomposition rates

AbstractDiversity, sporulation rates, and biomass of aquatic hyphomycetes (Kingdom Fungi) on leaf litter were examined to assess the effects of nutrient enrichment and flow regulation on the ecological integrity of the Saint John River, New Brunswick, Canada. Leaf decomposition rate was used as an indicator of ecological function, whereas fungal abundance and diversity were chosen as structural indicators. Leaf-litter bags of yellow birch (Betula alleghaniensis) were deployed at 8 sites, periodically retrieved, and analyzed during 2 consecutive years in unregulated and regulated reaches. The interaction between nutrient enrichment and flow regulation regime significantly affected leaf decomposition rate and fungal sporulation during summer and autumn and fungal diversity during autumn. Flow regulation regime was the primary driver for fungal diversity during summer. In contrast, nutrient enrichment significantly affected fungal biomass. In general, this large 7th-order river responded to flow regulation a...

Aquatic hyphomycetes, benthic macroinvertebrates and leaf litter decomposition in streams naturally differing in riparian vegetation

Small forest streams and their riparian vegetation are closely linked ecosystems. Stream consumers obtain most of their energy from leaf litter provided by the terrestrial vegetation. Thus, understanding the relationship between riparian vegetation, aquatic communities and litter decomposition may help explaining the variability in aquatic communities and processes among non-impacted streams, and anticipate their responses to anthropogenic-induced changes in the riparian vegetation. We surveyed 10 small non-impacted forest streams in central Portugal for riparian vegetation (species richness), benthic litter (species richness and biomass), aquatic hyphomycete conidia in transport (species richness and conidia concentration) and macroinvertebrates associated with benthic litter (taxon richness, density and biomass), during the litter fall peak. We found significant correlations between (a) aquatic communities and riparian vegetation species richness, (b) aquatic communities and benthic litter species richness and biomass and (c) within aquatic communities. Oak litter decomposition rates (from a previous experiment on the same streams) were also correlated with riparian tree species richness. This survey showed that spatial variability in riparian vegetation, benthic litter, aquatic communities and litter decomposition can be high even within a relatively small area, and allowed the identification of complex interactions between these components of the aquatic detrital food web. The positive correlation between aquatic hyphomycete species richness, macroinvertebrate taxon richness, litter decomposition and riparian tree species richness suggests that anthropogenic-induced decreases in riparian species richness may affect aquatic communities and processes. Surveys over streams naturally differing in environmental conditions may allow forecasting the response of aquatic communities and processes to anthropogenic activities.

Endophytic aquatic hyphomycetes in roots of riparian tree species of two Western Ghat streams

Bubble chamber incubation of surface sterilized segments of root bark and xylem of 10 riparian tree species of the Sampaje (475–500 m asl) and VʼBadaga (765–800 m asl) stream reaches of the Western Ghats yielded 20 species of endophytic aquatic hyphomycetes. Anguillospora crassa, A. longissima and Cylindrocarpon sp. were among the top five species in streams. A two-way ANOVA showed significantly higher species richness and counts of conidium in the tree species of Sampaje compared to VʼBadaga (p < 0.001), while two variables were not significantly different between bark and xylem. The total number of species recovered was slightly higher in bark than in xylem (14–19 vs. 13–17 spp.) and the average species richness between tissues did not differ significantly except for one tree species (Madhuca neriifolia: p < 0.05). The release of conidia from bark of only three tree species was significantly higher than from xylem (M. neriifolia and Canarium strictum: p < 0.05; Vateria indica: p < 0.01). Sorensen’s similarity index for bark as well as xylem between tree species was higher in Sampaje stream than in VʼBadaga stream (0.45–0.78 vs. 0.25–0.61). The diversity of aquatic hyphomycetes in bark and xylem was higher in the trees of Sampaje than VʼBadaga (3.1–3.3 vs. 2.7). A cluster analysis of aquatic hyphomycetes in bark and xylem resulted in two groups coinciding with the two streams. The results of this study revealed that assemblage and diversity of endophytic aquatic hyphomycetes in riparian tree roots are high in the mid-altitude Sampaje stream as previously documented for saprotrophic aquatic hyphomycetes.

Ethanol and phenanthrene increase the biomass of fungal assemblages and decrease plant litter decomposition in streams

Fungi, particularly aquatic hyphomycetes, have been recognized as playing a dominant role in microbial decomposition of plant litter in streams. In this study, we used a microcosm experiment with different levels of fungal diversity (species number and identity) using monocultures and combinations with up to five aquatic hyphomycete species (Articulospora tetracladia, Tricladium splendens, Heliscus submersus, Tetrachaetum elegans and Flagellospora curta) to assess the effects of ethanol and phenanthrene on three functional measures: plant litter decomposition, fungal biomass accrual and reproduction. Alder leaves were conditioned by fungi for 7days and then were exposed to phenanthrene (1mgL−1) dissolved in ethanol (0.1% final concentration) or ethanol (at the concentration used to solubilise phenanthrene) for further 24days. Exposure to ethanol alone or in combination with phenanthrene decreased leaf decomposition and fungal reproduction, but increased fungal biomass produced. All aspects of fungal activity varied with species number. Fungal activity in polycultures was generally higher than that expected from the sum of the weighted performances of participating species in monoculture, suggesting complementarity between species. However, the activity of fungi in polycultures did not exceed the activity of the most productive species either in the absence or presence of ethanol alone or with phenanthrene.

Copper and zinc affect the activity of plasma membrane H+-ATPase and thiol content in aquatic fungi.

Aquatic hyphomycetes are the major microbial decomposers of plant litter in streams. We selected three aquatic hyphomycete species with different abilities to tolerate, adsorb and accumulate copper and zinc, and we investigated the effects of these metals on H+-ATPase activity as well as on the levels of thiol (SH)-containing compounds. Before metal exposure, the species isolated from a metal-polluted stream (Heliscus submersus and Flagellospora curta) had higher levels of thiol compounds than the species isolated from a clean stream (Varicosporium elodeae). However, V. elodeae rapidly increased the levels of thiols after metal exposure, emphasizing the importance of these compounds in fungal survival under metal stress. The highest amounts of metals adsorbed to fungal mycelia were found in the most tolerant species to each metal, i.e. in H. submersus exposed to copper and in V. elodeae exposed to zinc. Short-term (10 min) exposure to copper completely inhibited the activity of H+-ATPase of H. submersus and V. elodeae, whilst zinc only led to a similar effect on H. submersus. However, at longer exposure times (8 days) the most metal-tolerant species exhibited increased H+-ATPase activities, suggesting that the plasma membrane proton pump may be involved in the acclimation of aquatic hyphomycetes to metals.

Fungal species diversity affects leaf decomposition after drought

The number of studies on the importance of biodiversity in stream ecosystem processes increased in the last years; however, little is still known on its role in scenarios of flow intermittency. In this study, we conducted a microcosm experiment to test the diversity‐insurance hypothesis on microbial decomposing oak leaves exposed to a drought event. Three microbial diversity levels were tested, single species and mixture assemblages of three or eight species of aquatic hyphomycetes. We also evaluated changes in leaf litter quality promoted by leaves desiccation to the shredder Schizopelex festiva. Fungal mixed assemblages resulted in higher decomposition and fungal sporulation rates than single species. This pattern was maintained after drought and decomposition was rapidly reassumed with rehydration. Fungal‐mediated decomposition seems to be more stimulated in the presence of rich (vs. single) fungal assemblages even after desiccation, particularly when species addition occurs at lower levels of richness. Shredder consumption was not affected by leaf desiccation, although feeding rates were consistently higher on leaves conditioned with eight fungal species and likely affected by the identity of the dominant taxa. Bottom‐up effects are expected on the food webs of detritus‐based streams affected by droughts; the intensity of these effects seems to be dependent on the level of decline promoted on decomposers richness by the environmental perturbation.