Diversity and novel lineages of black yeasts in Chaetothyriales from freshwater sediments in Spain.

Black yeasts comprise a group of Ascomycota of the order Chaetothyriales with highly variable morphology, a great diversity of ecological niches and life cycles. Despite the ubiquity of these fungi, their diversity in freshwater sediments is still poorly understood. During a survey of culturable Ascomycota from river and stream sediments in various sampling sites in Spain, we obtained 47 isolates of black yeasts by using potato dextrose agar supplemented with cycloheximide. A preliminary morphological study and sequence analyses of the internal transcribed spacer region (ITS) and the large subunit (LSU) of the nuclear rDNA revealed that most of the isolates belonged to the family Herpotrichiellaceae. We have confidently identified 30 isolates representing the following species: Capronia pulcherrima, Cladophialophora emmonsii, Exophiala equina, Exophiala pisciphila, Exophiala radicis, and Phialophora americana. However, we encountered difficulty in assigning 17 cultures to any known species within Chaetothyriales. Combining phenotypic and multi-locus phylogenetic analyses based on the ITS, LSU, ß-tubulin (tub2) and translation elongation factor 1-α (tef1-α) gene markers, we propose the new genus Aciculomyces in the Herpotrichiellaceae to accommodate the novel species Aciculomyces restrictus. Other novel species in this family include Cladophialophora denticulata, Cladophialophora heterospora, Cladophialophora irregularis, Exophiala candelabrata, Exophiala dehoogii, Exophiala ramosa, Exophiala verticillata and Phialophora submersa. The new species Cyphellophora spiralis, closely related to Cyphellophora suttonii, is described, and the phylogeny of the genus Anthopsis in the family Cyphellophoraceae is discussed. By utilizing these four markers, we were able to strengthen the phylogenetic resolution and provide more robust taxonomic assessments within the studied group. Our findings indicate that freshwater sediments may serve as a reservoir for intriguing black yeasts, which warrant further investigation to address gaps in phylogenetic relationships, particularly within Herpotrichiellaceae. Citation: Torres-Garcia D, García D, Réblová M, et al. 2023. Diversity and novel lineages of black yeasts in Chaetothyriales from freshwater sediments in Spain. Persoonia 51: 194-228. doi: 10.3767/persoonia.2023.51.05.

Distribution of the bioavailable and total content of copper and lead, in river sediments of the Jamapa-Atoyac fluvial system, Mexico.

The Jamapa-Atoyac fluvial system (JAFS) is tropical river system, which flows from the Pico de Orizaba, the highest elevation in Mexico, to end in the city of Veracruz, in the southern Gulf of Mexico. The geology of the watershed is dominated by Tertiary igneous rocks and Cretaceous limestones in the upper basin, and Quaternary alluvial sediments in the lower basin. Seventy percent of the land in the watershed has been deforested, and there are various urban and industrial areas. The JAFS is been widely known as source of trace elements to the coastal zone, and considered as contaminated. So, the aim of this study was to assess the environmental quality of the JAFS, using the total (TC) and the bioavailable (BF) concentrations of Cu and Pb, in surface fluvial sediments samples, in the dry (DS) and rainy (RS) seasons of the 2016. Average concentrations and ranges for the JAFS were CuT 10.2 ± 5.2 µg/g (2.2-41.5 µg/g); CuB 1.1 ± 1.4 µg/g (0.04-10.7 µg/g); PbT 5.0 ± 1.2 µg/g (1.8-10.9 µg/g); and PbB 0.7 ± 0.4 µg/g (0.1-2.0 µg/g). The BF only accounts for the ~ 10% of the total concentration for both elements, and is highly correlated to the mud content. No differences in average concentrations were found between the upper and lower bassins, nor among areas with different lithology. Cu presented higher concentrations during the RS, which suggest an enrichment of fluvial sediments from soil erosion, contrary, to Pb with higher concentrations during the DS. Although, some sampling stations, those located immediately after the Cordoba and Miguel Aleman cities, presented higher than average Cu and Pb concentrations, they did not exceeded the limits established by national environmental regulations, sediment quality guidelines, geoaccumulation index, and potential ecological risk indexes. Hence, the JAFS may be considered as not contaminated by Cu and Pb.

Clay mineral nanostructures regulate sequestration of organic carbon in typical fluvial sediments.

The association between clay minerals and organic carbon is pivotal for understanding transport, burial, and preservation processes of sedimentary organic carbon. However, fine-scale microscopic studies are still limited in assessing the effect of diverse clay mineral structures and properties on organic carbon sequestration. In this study, we employed X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy coupled with energy dispersive spectroscopy and electron energy loss spectroscopy analyses to investigate the nanoscale interaction between clay minerals and organic carbon of two typical fluvial sediment samples with contrasting clay mineral compositions and organic carbon origins. Sample from Taiwan shows abundant illite and chlorite with petrogenic organic carbon, while sample from Luzon has significant smectite with pedogenic organic carbon. We observed that the nanostructure of the clay minerals controls the distribution of organic carbon. In the Luzon sample, the organic carbon is tightly associated with smectite, occupying expandable interlayer spaces. In the Taiwan sample, however, the organic carbon is primarily confined on the surface and edge of illite. These findings offer valuable insights into the selective association of organic carbon with clay minerals and underscore the role of clay mineral nanolayer structures in governing the occurrence and preservation of organic carbon in sediments. A comprehensive understanding of these interactions is crucial for accurate assessments of carbon cycling and sequestration in the natural environment.

Quantification of the provenance contribution and sedimentary mixing effect of sediments in the Yellow River Basin, China.

Quantifying the source contributions of sediments in large fluvial systems with active wind erosion problems has crucial implications for understanding morphological evolution and ecological progression in the Earth system. Much effort have been focused on characterizing sediments of the Yellow River, but quantitation of the sediment source proportions at the basin-wide scale is lacking. To this end, the research aims to quantitatively elucidate the potential source contributions of sediments in the Yellow River based on geochemical characteristics and sediment fingerprinting technique, in order to identify sedimentary mixing effect and propose sustainable development strategies. In total, samples of four source groups (n = 107) and target floodplain sediments (n = 61) were collected and tested for elemental composition, grain size, magnetic susceptibility, and quartz grain microtextures. The results indicated that the optimal tracer combination was determined as P, Zn, and Ca. The average contributions of the "Tibetan Plateau", "Sandy deserts-Loess Plateau", "Loess Plateau", and "Loess Plateau-Qinling Mountains" source groups to the target sediments were 23.0 %, 21.5 %, 31.6 %, and 23.9 %, respectively. The accuracy of source apportionments was supported by the goodness of fit (GOF) and virtual mixtures tests. Meanwhile, large amounts of debris from surrounding mountains was transported to the Loess Plateau through fluvial processes and ultimately mixed with aeolian deposits, leading to sedimentary mixing effect. To maintain water balance and minimize erosion risk, the drought-resistant perennial planting and moderate grazing were recommended. The findings are instrumental in promoting soil and water conservation and disclosing fluvial and aeolian interaction on a global scale.

Assessment of hydrological, geological, and biological parameters of a river basin impacted by old Hg mining in NW Spain.

Mercury (Hg) is a toxic metal that can cause adverse effects for the health of ecosystems. The Caudal River is one of the main rivers in the Asturias region (NW Spain), whose basin is highly anthropized, hosting several Hg mines, closed in the last century. Arsenic (As) is also found in the mineral paragenesis of the Hg deposits, posing a greater environmental risk. In the mining sites, remaining old facilities and tailings continue to release these elements into the environment. In this work, samples of fluvial sediments and water were taken, both in areas affected by anthropic activity and in pristine areas, in order to establish the background levels for the critical elements. The mineralogical study of the sediments, combined with EDS microanalysis, is useful to identify mineralogical traps such as Fe oxides or clays to retain the As. The As content in all sampled sediments is above the threshold effect levels (TEL), the possible effect range within which adverse effects occasionally occur, according to the Canadian Sediment Quality Guidelines for the Protection of Aquatic Life. This fact is related to a naturally high geochemical background in the basin, due to the existing mineral deposits. The PEL threshold (the probable effect range within which adverse effects frequently occur) is exceeded by more than an order of magnitude in the sediments downstream of the Hg mines. In these points, the As content in the water, exceeding 700 µg L-1 As, is also above the quality standard established in Spanish legislation. As a result, the Caudal River tributaries in the lower part of the basin do not reach a good ecological state, according to the Hydrological Planning Office, and in some cases their state is deficient, showing low richness and high dominance of macroinvertebrates. Although the concentrations decrease with distance from the source, these findings justify the low ecological quality of the affected watercourses.

Insights into Some Onygenalean Fungi from Freshwater Sediments in Spain and Description of Novel Taxa.

During the course of a project investigating culturable Ascomycota diversity from freshwater sediments in Spain, we isolated 63 strains of cycloheximide-resistant fungi belonging to the order Onygenales. These well-known ascomycetes, able to infect both humans and animals, are commonly found in terrestrial habitats, colonizing keratin-rich soils or dung. Little is known about their diversity in aquatic environments. Combining morphological features and sequence analyses of the ITS and LSU regions of the nrDNA, we identified 14 species distributed in the genera Aphanoascus, Arachniotus, Arthroderma, Arthropsis, Emmonsiellopsis, Gymnoascoideus, Leucothecium, Malbranchea, and Myriodontium. Furthermore, three novel species for the genus Malbranchea are proposed as M. echinulata sp. nov., M. irregularis sp. nov., and M. sinuata sp. nov. The new genera Albidomyces and Neoarthropsis are introduced based on Arachniotus albicans and Arthropsis hispanica, respectively. Neoarthropsis sexualis sp. nov. is characterized and differentiated morphologically from its counterpart by the production of a sexual morph. The novel family Neoarthropsidaceae is proposed for the genera Albidomyes, Apinisia, Arachnotheca, Myriodontium, and Neoarthropsis, based on their phylogenetic relationships and phenotypic and ecological traits. Pseudoamaurascopsis gen. nov. is introduced to accommodate P. spiralis sp. nov., a fungus with unclear taxonomy related to Amaurascopsis and Polytolypa. We traced the ecology and global distribution of the novel fungi through ITS environmental sequences deposited in the GlobalFungi database. Studying the fungal diversity from freshwater sediments not only contributes to filling gaps in the relationships and taxonomy of the Ascomycota but also gives us insights into the fungal community that might represent a putative risk to the health of animals and humans inhabiting or transient in aquatic environments.

Dam construction reshapes sedimentary pollutant distribution along the Yangtze river by regulating sediment composition.

Dam construction has far-reaching impacts on pollutant accumulation and the pollutant-induced quality of aquatic environments. Nonetheless, its large-scale effects on pollutant distribution in sediments, which greatly contribute to the environmental impacts of coexisting pollutants, remain poorly understood. We collected sediments from the Yangtze River during the dry and normal seasons (with 'normal' defined in terms of precipitation level), and examined how dam construction alters the spatial trajectories of both inorganic and organic pollutants in the sediments. Sediment composition exhibited linear variation from the upper to the lower reaches, with clay and silt particles dominating the sediment in the Three Gorges Reservoir and sand particles dominating in the middle-lower reaches. Accordingly, upstream of the Three Gorges Dam (TGD), sedimentary carbon, nitrogen, phosphorus, heavy metal, polycyclic aromatic hydrocarbons (PAHs), and oxygenated PAHs (OPAHs) contents increased toward the TGD owing to its regulation of the spatial variation in sediment particle size. The TGD caused upstream sedimentary accumulation of pollutants to be higher nearer to the TGD than in the upper reaches by 17%-129% for carbon, nitrogen, and phosphorus, 7%-51% for heavy metals, 30% for PAHs, and 140% for OPAHs. Pollutant content was sharply lower below the TGD, by 0.58-11.15 times for carbon, nitrogen, and phosphorus, 0.1-2.6 times for heavy metals, 1.7 times for PAHs, and 5.6 times for OPAHs. Upstream of the TGD, levels of NH4+-N, the main form of N in the interstitial water of the Yangtze River, increased lineary toward the TGD, whereas those of NO3--N and NO2--N decreased. Sedimentary organic matter source contributions were consistent along the Yangtze River, being on an average 46% for C3 plants and 28% for soil organic substances, further confirming the dam's regulatory effect on pollutants. These findings provide a foundation for future assessments of the environmental impact of dam-induced river fragmentation and hydrological alterations, and for developing advanced watershed pollutant management strategies.

New and interesting species of Penicillium (Eurotiomycetes, Aspergillaceae) in freshwater sediments from Spain.

Penicillium species are common fungi found worldwide from diverse substrates, including soil, plant debris, food products and air. Their diversity in aquatic environments is still underexplored. With the aim to explore the fungal diversity in Spanish freshwater sediments, numerous Penicillium strains were isolated using various culture-dependent techniques. A preliminary sequence analysis of the ß-tubulin (tub2) gene marker allowed us to identify several interesting species of Penicillium, which were later characterized phylogenetically with the barcodes recommended for species delimitation in the genus. Based on the multi-locus phylogeny of the internal transcribed spacer region (ITS) of the ribosomal DNA, and partial fragments of tub2, calmodulin (cmdA), and the RNA polymerase II largest subunit (rpb2) genes, in combination with phenotypic analyses, five novel species are described. These are P.ausonanum in sectionLanata-Divaricata, P.guarroi in sect.Gracilenta, P.irregulare in sect.Canescentia, P.sicoris in sect.Paradoxa and P.submersum in sect.Robsamsonia. The study of several isolates from samples collected in different locations resulted in the reinstatement of P.vaccaeorum into sectionCitrina. Finally, P.heteromorphum (sect.Exilicaulis) and P.tardochrysogenum (sect.Chrysogena) are reported, previously only known from Antarctica and China, respectively.

Dam construction attenuates trace metal contamination in water through increased sedimentation in the Three Gorges Reservoir.

Dam construction has a far-reaching impact on trace metal accumulation and the metal-induced quality of the aquatic environment. However, the long-term impacts of dam construction and impoundments on the spatial distribution of trace metals and water quality remain poorly understood. Here, we found that the concentrations of trace metals in the mainstream water of the world's largest reservoir, Three Gorges Reservoir (TGR), decreased after impoundment, while their concentrations and contamination in the sediments of the water-level fluctuation zone increased significantly, especially for anthropogenic sources of metals such as cadmium, lead, and zinc. The spatial and temporal variations of anthropogenic metals in the sediments revealed increased anthropogenic dominance in their distribution under current hydrological management, especially for the urban area of the upper TGR. Sediment fluxes, particle composition, and extreme climate modulated the distribution of trace metals in the sediments. The results demonstrate that human activities have increasingly determined the distribution and contamination state of trace metals in the mainstream TGR. However, in contrast to our previously thought, the anthropogenic discharge of trace metals did not adversely affect water quality. Our results indicate that dam construction in riverine systems attenuates trace metal contamination in water through sediment sorting and deposition.

Late Miocene sedimentary environments in south-western Amazonia (Solimões Formation; Brazil).

In Miocene times a vast wetland existed in Western Amazonia. Whereas the general development of this amazing ecosystem is well established, many questions remain open on sedimentary environments, stratigraphical correlations as well as its palaeogeographical configuration. Several outcrops located in a barely studied region around Eirunepé (SW Amazonas state, Brazil) were investigated to obtain basic sedimentological data. The observed deposits belong to the upper part of the Solimões Formation and are biostratigraphically dated to the Late Miocene. Vertically as well as laterally highly variable fine-grained clastic successions were recorded. Based on the lithofacies assemblages, these sediments represent fluvial deposits, possibly of an anastomosing river system. Sand bodies formed within active channels and dominant overbank fines are described (levees, crevasse splays/channels/deltas, abandoned channels, backswamps, floodplain paleosols). Lacustrine environments are restricted to local floodplain ponds/lakes. The mollusc and ostracod content as well as very light δ18O and δ13C values, measured on ostracod valves, refer to exclusively freshwater conditions. Based on palaeontological and geological results the existence of a long-lived lake ("Lake Pebas") or any influx of marine waters can be excluded for that region during the Late Miocene.

Effect of Using Different Chemical Dispersing Agents in Grain Size Analyses of Fluvial Sediments via Laser Diffraction Spectrometry.

Laser diffraction spectrometry allows for efficiently obtaining high-resolution grain size data. However, pretreatment and dispersion of aggregates in sediment samples are essential pre-requisites for acquiring accurate results using this method. This study evaluates the effectiveness of five dispersing agents in deflocculating the investigated fluvial sediments and the resulting grain size distribution obtained by laser diffraction spectrometry. We also examine the ability of the different dispersing agents to deflocculate sediment samples treated by thermal combustion. Distilled water presented a low efficiency in deflocculating the samples and yielded a near-zero clay content for samples with an expected clay content. The other chemical dispersants were effective in dispersing aggregates and yielding clay, albeit with different efficiencies. Calgon had the highest dispersing ability, followed closely by sodium tripolyphosphate. The performance of chemical treatment with sodium oxalate approaches that of sodium tripolyphosphate. However, it leads to the formation of precipitates in the samples, obscuring the actual grain size data. Sodium pyrophosphate derived the least amount of deflocculation among the four chemical dispersants. Furthermore, all the chemical dispersants were found to be ineffective in dispersing aggregates in samples treated by thermal combustion.

Tracking the sources of allochthonous organic matter along a subtropical fluvial-estuarine gradient using molecular proxies in view of land uses.

Sedimentary sterols and linear alkylbenzenes associated with allochthonous organic matter (AOM) inputs were studied in surface sediments along the Tubarão riverbed, South Brazil. These markers were analysed in terms of concentrations, diagnostic ratios and by using multivariate analyses to identify the main organic matter sources. It was necessary to integrate all these factors to distinguish the sources and determine sewage contamination. Phytosterols predominated over faecal sterols, but the contributions of livestock waste along the river (determined in 50% of the sites) were confirmed by the fingerprint analysis. Raw sewage contamination was verified at one site, according to the increased levels of sewage molecular markers and confirmed by the multivariate analyses and diagnostic ratios calibrated to this region. A possible synergistic effect between inorganic nanoparticles from coal mine waste and organic contaminants related to AOM input was suggested and should not be ignored since both activities severely contribute to the environmental changes in much of this fluvial-estuarine gradient from the South Atlantic.

Assessing aquitard integrity in a complex aquifer - aquitard system contaminated by chlorinated hydrocarbons.

This study investigates for the first time the integrity of multiple stacked aquitards with different degrees of contaminant degradation. Aquitard integrity was assessed in a contaminated, multi-layered, alluvial aquifer-aquitard system (Ferrara, northern Italy). The system was contaminated by mixed organic contaminants of industrial origin (mostly chlorinated ethenes) that were illegally disposed in an urban dump four to five decades ago. High spatial resolution profiles of hydraulic head, geochemistry and chlorinated hydrocarbon concentrations were determined through the multi-layered system via discrete interval sampling of continuous cores and multilevel groundwater sampling, at three locations aligned along a transect adjacent to the buried waste to a maximum depth of 53 m below the water table. The profiles revealed that the two shallow aquitards had low integrity with respect to impeding downward migration of dense non-aqueous phase liquid (DNAPL), and provided little protection to the underlying aquifers against DNAPL contamination due to preferential pathways through imperceptible fractures and/or permeable micro-beds. However, both aquitards inhibited downward DNAPL migration to some extent due to DNAPL retention along its flow paths and accumulation at lower permeability interfaces, with decreasing peak concentrations at the top of successively deeper aquitard units. Moreover, both aquitards enhanced contaminant biodegradation due to the occurrence of organic rich sub-layers, influencing the contaminant plume composition, mobility and fate in the underlying and overlying aquifers. The deepest aquitard showed evidence of DNAPL accumulation at the top and slow diffusion-dominated transport consistent with 40 years of transport, suggesting higher integrity compared to the two shallower aquitards. However, the occurrence of micro-fractures and/or discontinuities in the aquitard upgradient under the dump (source) is the most likely explanation for contamination of the deepest aquifer. Analytical 1-D simulations of the diffusion profiles in the deepest aquitard revealed that DNAPL contamination down to the top of this aquitard occurred with minimal delay after DNAPL waste disposal began. The results highlight the necessity of high-resolution vertical profiling for assessing the presence of imperceptible features relevant to DNAPL migration and integrity of individual aquitards affecting organic contaminant source zone mass and phase distributions over decades.

The spatial and vertical distribution of heavy metal contamination in sediments of the Three Gorges Reservoir determined by anti-seasonal flow regulation.

The contamination of heavy metals in sediments of the Three Gorges Reservoir (TGR) is increasingly concerned as a major issue for water quality since the full impoundment. In this study, the sediment profiles in the riparian and submerged areas from Fuling to Zigui in the middle-low TGR mainstream were collected to investigate the stratified distribution of heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) and assess their contamination and potential eco-risk. The results showed that the concentrations of these metals in the riparian sediments did not present a marked spatial trend except the concentrations of Cd that increased towards the dam. However, the metal concentrations (except Cd) in the submerged sediments were generally higher near the dam. The concentrations of heavy metals in the riparian sediments did not show marked vertical variation, while in the submerged sediments they fluctuated dramatically with depth, indicating the metal accumulation processes in last few years. Sediment grain sizes as an indicator of hydrodynamic regimes dominated the vertical distribution of heavy metals over organic matters and Fe/Mn oxide/hydroxides. The sediments from both riparian and submerged areas of the TGR were contaminated by anthropogenic metals of Cd, Cu and Pb that were mainly from the ore mining, fossil fuel combustion, agricultural pollution and atmospheric deposition. Cadmium was a major metal pollutant in the sediments with a high contamination and potential eco-risk level. The results of this study indicate that the sorting of sediments with the anti-seasonal flow regulation determines the spatial and temporal distribution of heavy metal contamination in the sediments, and the impoundment stages of the TGR in history regulate the accumulation processes of the metals.

Spatial variation of heavy metal contamination in the riparian sediments after two-year flow regulation in the Three Gorges Reservoir, China.

Regular impoundment of the Three Gorges Reservoir (TGR) with intensified human activities in the watershed imparts a significant effect on the environmental changes in the riparian zone. In this study, six heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) in the riparian sediments of the entire TGR mainstream were investigated in 2014 and 2016 to identify their contamination and risk characteristics and decipher the main factors for the variation of the metal contamination. The results showed that the concentrations of the heavy metals in the sediments did not vary significantly between 2014 and 2016, and their contamination degrees decreased in the order of Cd> > Cu ≈ Zn > Pb > Cr ≈ Ni in 2014 and Cd> > Zn > Cu ≈ Pb > Cr ≈ Ni in 2016. The potential eco-risk of Cd was extremely high in the two years, while the eco-risk of other metals was very low. The sediments showed a moderate to high contamination level, a high potential eco-risk but a low toxic risk to aquatic biota in the two years. Spatially, the contamination and risk levels of heavy metals were relatively higher in the downstream TGR region in 2014 except for the sites close to the urban areas but in the upper-middle TGR region in 2016. Increasing anthropogenic influence contributed to the high contamination and risk levels of Cd, Cu, Pb and Zn in the upper-middle region in 2016. The results indicated that the Cd contamination in the riparian sediments of the TGR was still a vital environmental issue, and the decreased sediment inputs from the upstream major tributaries, the periodic and anti-seasonal flow regulation, local geomorphological characteristics and anthropogenic activities determined the contamination distribution of heavy metals in the riparian sediments.