- IMARENABIO - La Serna 58 (24007 Leon, Spain)
- University of León - Universidad de León, Diatom Lab, Department Memberadd
- Diatom taxonomy, Freshwater Biology, Bioindicators, Algae, Geometric Morphometrics, Phycology, and 29 moreLimnology, Phycology diatoms algae, Diatom Taxonomy and Ecology, Freshwater Ecology, Fish Ecology, Diatoms, Hydrobiology, Food web ecology, Trophic Ecology, Eutrophication, Shallow lake ecology, Morphometrics, Didymosphenia geminata, Ecology, Biology, Climate Change, Biodiversity, Environmental Science, Environmental Sustainability, Taxonomy, Systematics, Freshwater Benthic algae, Diatoms as indicators, Stream Periphyton, Freshwater Biology and Limnology, Benthic Diatoms, Diatom, Bioassessment, and Bioindicationedit
- Main research interests: - Taxonomy and ecology of freshwater diatoms - Biogeography of continental microalgae -... moreMain research interests:
- Taxonomy and ecology of freshwater diatoms
- Biogeography of continental microalgae
- Limnology of shallow lakes
Principales líneas de trabajo: Taxonomía y ecología de diatomeas de agua dulce. Índices diatomológicos. Bioindicadores. Índices bióticos de la calidad del agua. Biomonitorización. Directiva Marco del Agua. Microalgas en biorreactores. Depuración de aguas residuales.edit
High-resolution images of phytoplankton cells such as diatoms or desmids, which are useful for monitoring water quality, can now be provided by digital microscopes, facilitating the automated analysis and identification of specimens.... more
High-resolution images of phytoplankton cells such as diatoms or desmids, which are useful for monitoring water quality, can now be provided by digital microscopes, facilitating the automated analysis and identification of specimens. Conventional approaches are based on optical microscopy; however, manual image analysis is impractical due to the huge diversity of this group of microalgae and its great morphological plasticity. As such, there is a need for automated recognition techniques for diagnostic tools (e.g. environmental monitoring networks, early warning systems) to improve the management of water resources and decision-making processes. Describing the entire workflow of a bioindicator system, from capture, analysis and identification to the determination of quality indices, this book provides insights into the current state-of-the-art in automatic identification systems in microscopy.
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Las diatomeas son un grupo de algas microsc{\'{o}}picas extremadamente diversificado que viven en los ecosistemas acu{\'{a}}ticos de todo el mundo, a pesar de lo cual los estudios sobre estos organismos en la regi{\'{o}}n del Estrecho son... more
Las diatomeas son un grupo de algas microsc{\'{o}}picas extremadamente diversificado que viven en los ecosistemas acu{\'{a}}ticos de todo el mundo, a pesar de lo cual los estudios sobre estos organismos en la regi{\'{o}}n del Estrecho son escasos. Esta monograf{\'{i}}a presenta el primer estudio sistem{\'{a}}tico sobre las diatomeas de Ceuta, describiendo m{\'{a}}s de 250 especies encontradas durante muestreos efectuados en ambientes tanto dulceacu{\'{i}}colas como costeros. Adem{\'{a}}s de su inter{\'{e}}s taxon{\'{o}}mico y biogeogr{\'{a}}fico, las diatomeas ceut{\'{i}}es se revelan como unos excelentes bioindicadores de la calidad del agua en los ecosistemas que habitan.
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This catalogue aims to compile the information available on continental (recent and fossil) diatoms in Portugal, including the Archipelagos of Madeira and Azores, since the early beginnings of the diatom studies in Portugal at the middle... more
This catalogue aims to compile the information available on continental
(recent and fossil) diatoms in Portugal, including the Archipelagos of
Madeira and Azores, since the early beginnings of the diatom studies in
Portugal at the middle of the XIXth century until 2010.
The diatom taxa are presented following an updated taxonomy;
nevertheless, in order to provide a historical overview, the nomenclatural
synonyms found in the literature from Portugal are also included. For the
1381 taxa the following information is presented: basionym, nomenclatural
synonyms, citations (with the precise indication of the sampling sites),
frequent taxonomical synonyms and a distribution map.
(recent and fossil) diatoms in Portugal, including the Archipelagos of
Madeira and Azores, since the early beginnings of the diatom studies in
Portugal at the middle of the XIXth century until 2010.
The diatom taxa are presented following an updated taxonomy;
nevertheless, in order to provide a historical overview, the nomenclatural
synonyms found in the literature from Portugal are also included. For the
1381 taxa the following information is presented: basionym, nomenclatural
synonyms, citations (with the precise indication of the sampling sites),
frequent taxonomical synonyms and a distribution map.
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The authors present a taxonomic study of benthic diatoms collected from coastal rocks in seven northern Mediterranean sites (Italy, Spain, Greece, Turkey) in spring of 2010. An iconographic catalogue of high-quality SEM and light... more
The authors present a taxonomic study of benthic diatoms collected from coastal rocks in seven northern Mediterranean sites (Italy, Spain, Greece, Turkey) in spring of 2010. An iconographic catalogue of high-quality SEM and light microscopic images, plus detailed taxonomic, nomenclatural and bibliographic information, are provided as a practical reference for further taxonomic and floristic studies on 91 plates. 120 representative diatom taxa, among them several poorly known species, selected from 23 samples, are described in terms of their abundance. The authors provide detailed information on the type material of each diatom species, a list of synonyms, a comparison of morphometric data provided in the literature (in tables) and a series of iconographic SEM-images which illustrate the taxon’s morphological variability, plus an exhaustive list of references. Nomenclature, taxonomy and systematic position of the described taxa are updated. Eight taxa are described as new to science and another seven are nomenclaturally recombined. Eight taxa are new records for the Mediterranean Sea and for five taxa Scanning Electron Microscope (SEM) images are presented for the first time.
An exhaustive reference list and indices of taxa conclude this volume and make it a valuable source of information for biologists working on benthic diatoms in general, not only of the Mediterranean region.
An exhaustive reference list and indices of taxa conclude this volume and make it a valuable source of information for biologists working on benthic diatoms in general, not only of the Mediterranean region.
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En esta obra se recogen los 200 taxones de diatomeas (pertenecientes a 60 géneros distintos) más importantes de las identificadas en más de 600 muestras de epiliton fluvial recogidas durante campañas de muestreo efectuadas entre 2003 y... more
En esta obra se recogen los 200 taxones de diatomeas (pertenecientes a 60 géneros distintos) más importantes de las identificadas en más de 600 muestras de epiliton fluvial recogidas durante campañas de muestreo efectuadas entre 2003 y 2007 en la parte española de la cuenca, dentro de los programas de seguimiento del estado de las masas de agua superficiales de la Confederación Hidrográfica del Duero. Esta selección atiende a un doble criterio, que valora la importancia de cada taxón dentro del inventario general de la cuenca, de forma que se han considerado las especies más abundantes y/o más ampliamente distribuidas en la zona de estudio; así como, por su interés florístico o biogeográfico, se incluyen algunos taxones adicionales (especies exóticas, poco conocidas o que representan novedades para la Península). Para cada especie se ofrece la siguiente información: una descripción morfológica y autoecológica (parte II), un mapa de distribución en la cuenca del Duero (parte III) y una serie de fotografías en microscopía óptica de campo claro donde se ilustra la variabilidad morfológica de cada taxón, reunidas en 36 láminas (parte II).
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This thesis is based on the following papers: • Blanco S, Bécares E, Fernández-Aláez M 2008. Efficiency of top-down control depends on nutrient concentration in a shallow lake: a mesocosm study. Mar Freshwat Res 59: 922-930. • Blanco S,... more
This thesis is based on the following papers: • Blanco S, Bécares E, Fernández-Aláez M 2008. Efficiency of top-down control depends on nutrient concentration in a shallow lake: a mesocosm study. Mar Freshwat Res 59: 922-930. • Blanco S, Romo S, Villena MJ, 2004. Experimental study on the diet of mosquitofish (Gambusia holbrooki) under different ecological conditions in a shallow lake. Int Rev Hydrobiol 89: 250-262. • Blanco S, Romo S, Villena MJ, Martínez S 2003. Fish communities and food web interactions in some shallow Mediterranean lakes. Hydrobiologia 506: 473-480 • Blanco S, Romo R 2006. Ictiofauna del Lago de la Albufera de Valencia: evolución histórica y situación actual. Bol R Soc Esp Hist Nat Secc Biol 101: 45-56 • Blanco S, Romo S, Fernández-Aláez M, Bécares E 2007. Response of epiphytic algae to nutrient loading and fish density in a shallow lake: a mesocosm experiment. Hydrobiologia 600: 65-76
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Para facilitar y homogeneizar el tratamiento y la interpretación de la información generada en las redes de control biológico se presenta una colección de fichas descriptivas de los organismos fitobentónicos que incluyen: nombre... more
Para facilitar y homogeneizar el tratamiento y la interpretación de la información generada en las redes de control biológico se presenta una colección de fichas descriptivas de los organismos fitobentónicos que incluyen: nombre científico, común, sinónimo, propiedades, descripción, ecología, ruta taxonómica e índices y métricas, foto o ilustración incluyendo la propiedad y el autor. Esta guía ha sido elaborada por la Dirección General del Agua y forma parte de una colección de cinco tomos.
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"The Duero River Basin, with an area of 97290 km2 and more than 40000 km of streams, is the largest one in the Iberian Peninsula, and lies mainly under Mediterranean continentalized bioclimate. Aquatic ecosystems are endorheic and main... more
"The Duero River Basin, with an area of 97290 km2 and more than 40000 km of streams, is the largest one in the Iberian Peninsula, and lies mainly under Mediterranean continentalized bioclimate. Aquatic ecosystems are endorheic and main watercourses are regulated and highly anthropized. As in every lotic environment, benthic algae play a key role in the structure and functioning of its ecosystems and, within this group, diatoms represent the most abundant and diversified component. Their biological features make them excellent water quality indicators, and this has promoted their study at international level. As a result of the implementation of the Water Framework Directive of the European Union, ecological status biomonitoring networks have been established in all Iberian basins, based on the use, among others, of diatom indices, which has led to the need of more detailed taxonomic and ecological studies on these organisms. Despite their relevancy, such works are still scarce in Spain. In the Duero Basin, up to date more than 500 diatom species have been recorded, a high floristic richness that contrasts with analogue regions, this being related to the large diversity of environmental conditions included within this zone.
The aim of the present work is to elaborate a practical identification guide in accordance with the needs of technicians and biologists evaluating water biological quality in the Duero Basin. This book gathers the 200 main diatom taxa in terms of abundance and occurrence, selected from more than 600 samples of river epilithon collected during annual surveys carried out between 2003 and 2007 in the Spanish part of the basin. Certain taxa that could not be identified to specific level are also presented. For every diatom species, the following information is provided: a mor-phometric and autoecological description, a selection of illustrated bibliographic references and an iconographic series illustrating the taxon’s morphological variability, with a total of 3110 photographs in light and scanning electron microscopy gathered into 109 plates. The nomenclature, taxonomy and systematic position of taxa follow the most recent phycological literature. 116 species new to the Duero Basin and 34 species new to the Iberian Peninsula are presented."
The aim of the present work is to elaborate a practical identification guide in accordance with the needs of technicians and biologists evaluating water biological quality in the Duero Basin. This book gathers the 200 main diatom taxa in terms of abundance and occurrence, selected from more than 600 samples of river epilithon collected during annual surveys carried out between 2003 and 2007 in the Spanish part of the basin. Certain taxa that could not be identified to specific level are also presented. For every diatom species, the following information is provided: a mor-phometric and autoecological description, a selection of illustrated bibliographic references and an iconographic series illustrating the taxon’s morphological variability, with a total of 3110 photographs in light and scanning electron microscopy gathered into 109 plates. The nomenclature, taxonomy and systematic position of taxa follow the most recent phycological literature. 116 species new to the Duero Basin and 34 species new to the Iberian Peninsula are presented."
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An Encyonema population collected in the Zambeze River near the Victoria Falls, Namibia, is here described and illustrated in detail with the aid of LM and SEM microscopy. This taxon had already been presented in the literature under the... more
An Encyonema population collected in the Zambeze River near the Victoria Falls, Namibia, is here described and illustrated in detail with the aid of LM and SEM microscopy. This taxon had already been presented in the literature under the name E. volkii, the reasons leading to treat this species as a new, independent taxon are here discussed. Encyonema ratpanati sp. nov. can be easily distinguished from E. volkii by its more linear outline (length-to-width ratio up to 4.3 vs. up to 3.5 in E. volkii), its lower degree of dorsiventrality, lack of rostrate apices throughout the whole diminution series, wider axial area and denser areolation (>26 lineolae per 10 µm and not 20–22 as in E. volkii) Se describe una población de Encyonema recogida en el río Zambeze, cerca de las cataratas Victoria, Namibia, y se ilustra en detalle con la ayuda de microscopía óptica y electrónica. Este taxón ya había sido presentado en la literatura bajo el nombre de E. volkii, se discuten aquí las razones ...
Research Interests: Humanities and Taxon
The time required for diatom assemblages to integrate the abiotic variables of the aquatic environment has been subject of discussion for many years, with contrasting opinions as shown by field observations and experiments. Numerous... more
The time required for diatom assemblages to integrate the abiotic variables of the aquatic environment has been subject of discussion for many years, with contrasting opinions as shown by field observations and experiments. Numerous diatom-based water quality indices are being used in the bioassessment of freshwaters; one of the most widely used (Specific Polluosensitivity Index or SPI) is compared in this study with water quality status as measured by the Water Quality Index (WQI) obtained from limnological parameters measured at 37 fluvial stations belonging to the Duero Basin (NW Spain). The correlation existing between both metrics was determined using different time lags between water and diatom sample collection. Results show that the correlation coefficient increases as the time gap decreases, but is maximal when comparing WQI scores measured one month before diatom sampling. We thus confirm the initial hypothesis that diatom indices actually indicate past (1 month ago) and n...
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Gomphosphenia minima sp. nov. is a new freshwater diatom described from central Portugal, found in samples from a mountain stream. The species is described here based on light and scanning electron microscopy. This taxon is compared with... more
Gomphosphenia minima sp. nov. is a new freshwater diatom described from central Portugal, found in samples from a mountain stream. The species is described here based on light and scanning electron microscopy. This taxon is compared with other Gomphosphenia taxa such as G. fontinalis, G. lingulatiformis and G. tackei. Gomphosphenia minima sp. nov. is characterized by clavate to linear-lanceolate valves with rounded apices and a wide axial area not clearly separated from the central area. This taxon can be confused with G. fontinalis in terms of length and the shape of the central and axial area but they can be easily differentiated because the new species is narrower and the stria density is lower. The new species was found in low abundance in February 2012 and the stream had low electric conductivity levels, neutral pH values, low water temperature and low nutrient content.
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ABSTRACT Fragilaria construens var. subsalina is a common diatom found in a wide variety of aquatic systems worldwide. It was described by Hustedt (1925) from brackish waters in Oldesloe, Germany; a lectotype specimen was established by... more
ABSTRACT Fragilaria construens var. subsalina is a common diatom found in a wide variety of aquatic systems worldwide. It was described by Hustedt (1925) from brackish waters in Oldesloe, Germany; a lectotype specimen was established by Simonsen (1987). We analysed the ultrastructure of specimens from the lectotype material by means of light (LM) and scanning electron microscopy (SEM) and show that this taxon should be placed at the species level within the genus Pseudostaurosira (as Pseudostaurosira subsalina). A similar but distinct taxon from the United States, found in waters with low electrolyte content, is proposed as a new species of Pseudostaurosira, namely Pseudostaurosira americana sp. nov. We also describe a second new species from Spain (Pseudostaurosira alvareziae sp. nov.), found in waters with moderate conductivity, which was misidentified as P. subsalina in the past. A morphometric analysis of the valve shape supports the morphological separation between the three species. The present study clarifies the taxonomy, ecology and systematic position of these three taxa and provides a comparison with other, similar taxa.
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During the investigations of the diatom flora of Lake Qinghai, China (see Liu et al. 2020 for details), specimens of an undescribed species of Pinnularia Ehrenberg (1843: 45) were encountered, which are hereby illustrated and described.
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The Krka River is located at Balkan Peninsula in the Dinaric region of Croatia and it is a typical groundwater-fed karst river characterized by an unusual phenomenon-tufa. Tufa designates porous CaCO3 deposits forming under specific... more
The Krka River is located at Balkan Peninsula in the Dinaric region of Croatia and it is a typical groundwater-fed karst river characterized by an unusual phenomenon-tufa. Tufa designates porous CaCO3 deposits forming under specific physical and chemical conditions and hosting very diverse freshwater biota. Karst springs are considered one of the most diverse habitats for diatoms and are usually inhabited by specific diatom assemblages, which include the Krka spring zone. However, such habitats are particularly impacted by human activities, so previous studies have recently been conducted to raise awareness of the importance of karstic spring zones, especially because they are inhabited by specific and rare species. During the research at Krka River, samples were collected in the spring zone in May 2017, and the observations revealed the existence of a one Cymbopleura species characterized by slightly convex to almost linear valves, which are slightly protracted, broadly rounded and...
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Increased salt concentration is one of the most widespread problems affecting freshwater worldwide. Aquatic communities, and in particular periphytic diatoms, react to this alteration in water quality by modifying their structural... more
Increased salt concentration is one of the most widespread problems affecting freshwater worldwide. Aquatic communities, and in particular periphytic diatoms, react to this alteration in water quality by modifying their structural parameters and physiology at the individual level, which is commonly manifested by the appearance of teratological forms. The present work presents the results of an experimental laboratory study in which a biofilm grown on artificial substrates was subjected to a gradient of water conductivities for 4 weeks. The results show an increase in the number of deformed valves over time proportionally to the increase in conductivity for each experimental treatment. These effects are also verified by analyzing the concentration of chlorophyll-a in the experimental biofilms, which demonstrate a metabolic response to the induced osmotic stress. No changes were recorded; however, in species richness or diversity of taxa present in the treatments. Our results, therefore, confirm at the experimental level numerous previous field observations about the harmful effect of salinity on periphytic diatoms, and also their ability to reintegrate with the new stress conditions.
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Research Interests: Diatom and Contamination
of diatom species. The TDIR index scores ranged from 1 (ultraoligotrophic) to 6 (hypereutrophic). The TDIR showed good performance for the trophic classification of reservoirs. In contrast, the borrowed diatom indices developed in... more
of diatom species. The TDIR index scores ranged from 1 (ultraoligotrophic) to 6 (hypereutrophic). The TDIR showed good performance for the trophic classification of reservoirs. In contrast, the borrowed diatom indices developed in subtropical rivers underestimated the water quality, whereas the diatom index developed for lakes in temperate regions overestimated the water quality of our reservoirs. Moreover, we calculated new records of indicative values, and some well-cited species had different optimum and tolerances values concerning other well-known studies. TDIR provides an applicable index and contributes as a reliable tool for assessing the water quality and ecological status of tropical reservoirs.
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Nowadays, piggery wastewater (PWW) management still represents an unsolved global environmental problem. Photosynthetic processes have emerged as an innovative biological platform capable of performing a costeffective treatment of... more
Nowadays, piggery wastewater (PWW) management still represents an unsolved global environmental problem. Photosynthetic processes have emerged as an innovative biological platform capable of performing a costeffective treatment of wastewater with a concomitant assimilation of nutrients into biomass. In this work, the performance of a purple phototrophic bacteria photobioreactor (PPB-PBR) coupled with a microalgae-bacteria photobioreactor (MB-PBR) was assessed during the treatment of PWW at an hydraulic retention time (HRT) of 12.2 (stage I) and 6.2 days (stages II-VI) and intensities of near-infrared radiation in the PPB-PBR of 30 W m − 2 (stages I-II) and 114 W m − 2 (stages III-IV). Maximum removal efficiencies of total dissolved organic carbon (TOC-RE) and total dissolved nitrogen (TN-RE) of 91% and 82%, respectively, were recorded at an HRT of 12.2 days. The decrease in HRT to 6.2 days reduced the TOC-RE and TN-RE in both photobioreactors, but the increase in near-infrared radiation enhanced TOC-RE in the PPB-PBR, contributing to a global carbon recovery of 67% via assimilation in the form of PPB biomass. PPB-PBR was highly efficient in carbon assimilation, while MB-PBR enhanced nitrogen and total suspended solids removals, with a contribution to TN-RE of 63% and a global decrease in TSS of 76%. The culture broth of PPB-PBR was dominated by Rhodopseudomonas sp. up to 54%, supported by the high HRT and the increase in near-infrared radiation, while the sequential MB-PBR favoured the dominance of Mychonastes homosphaera. This work demonstrated, for the first time, the high efficiency of sequentially coupling PPB and microalgae for the treatment of PWW.
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BACKGROUND AND OBJECTIVE Training a deep convolutional neural network (CNN) for automatic image classification requires a large database with images of labeled samples. However, in some applications such as biology and medicine only a few... more
BACKGROUND AND OBJECTIVE Training a deep convolutional neural network (CNN) for automatic image classification requires a large database with images of labeled samples. However, in some applications such as biology and medicine only a few experts can correctly categorize each sample. Experts are able to identify small changes in shape and texture which go unnoticed by untrained people, as well as distinguish between objects in the same class that present drastically different shapes and textures. This means that currently available databases are too small and not suitable to train deep learning models from scratch. To deal with this problem, data augmentation techniques are commonly used to increase the dataset size. However, typical data augmentation methods introduce artifacts or apply distortions to the original image, which instead of creating new realistic samples, obtain basic spatial variations of the original ones. METHODS We propose a novel data augmentation procedure which generates new realistic samples, by combining two samples that belong to the same class. Although the idea behind the method described in this paper is to mimic the variations that diatoms experience in different stages of their life cycle, it has also been demonstrated in glomeruli and pollen identification problems. This new data augmentation procedure is based on morphing and image registration methods that perform diffeomorphic transformations. RESULTS The proposed technique achieves an increase in accuracy over existing techniques of 0.47%, 1.47%, and 0.23% for diatom, glomeruli and pollen problems respectively. CONCLUSIONS For the Diatom dataset, the method is able to simulate the shape changes in different diatom life cycle stages, and thus, images generated resemble newly acquired samples with intermediate shapes. In fact, the other methods compared obtained worse results than those which were not using data augmentation. For the Glomeruli dataset, the method is able to add new samples with different shapes and degrees of sclerosis (through different textures). This is the case where our proposed DA method is more beneficial, when objects highly differ in both shape and texture. Finally, for the Pollen dataset, since there are only small variations between samples in a few classes and this dataset has other features such as noise which are likely to benefit other existing DA techniques, the method still shows an improvement of the results.
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Traditional microscope imaging techniques are unable to retrieve the complete dynamic range of a diatom species with complex silica-based cell walls and multi-scale patterns. In order to extract details from the diatom, multi-exposure... more
Traditional microscope imaging techniques are unable to retrieve the complete dynamic range of a diatom species with complex silica-based cell walls and multi-scale patterns. In order to extract details from the diatom, multi-exposure images are captured at variable exposure settings using microscopy techniques. A recent innovation shows that image fusion overcomes the limitations of standard digital cameras to capture details from high dynamic range scene or specimen photographed using microscopy imaging techniques. In this paper, we present a cell-region sensitive exposure fusion (CS-EF) approach to produce well-exposed fused images that can be presented directly on conventional display devices. The ambition is to preserve details in poorly and brightly illuminated regions of 3-D transparent diatom shells. The aforesaid objective is achieved by taking into account local information measures, which select well-exposed regions across input exposures. In addition, a modified histogram equalization is introduced to improve uniformity of input multi-exposure image prior to fusion. Quantitative and qualitative assessment of proposed fusion results reveal better performance than several state-of-the-art algorithms that substantiate the method's validity.
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Background: Due to their isolation, islands offer excellent areas for the study of distribution of benthic diatoms. On the other hand, diatoms bearing canal raphe have received less attention compared to other groups of diatoms such as... more
Background: Due to their isolation, islands offer excellent areas for the study of distribution of benthic diatoms. On the other hand, diatoms bearing canal raphe have received less attention compared to other groups of diatoms such as Navicula, Pinnularia or Amphora . Questions: Is it possible that thermal springs on islands offer a refuge for infrequent diatom species? Studied species: Platichthys furnensis C. Delgado, V. Gonçalves & S.F.P. Almeida sp. nov. Study site and dates: The species here described was collected in the epilithon of a thermal spring in São Miguel Island (Azores Archipelago, Portugal) in September 2015. Methods: This new taxon was compared to other diatom species of the genera Nitzschia , Tryblionella , Entomoneis and Hantzschia and to the other species of the genus Platichthys . The morphology is documented by light and scanning electron images and discussed in detail. Results: Platichthys furnensis was found in a thermal pool, a similar habitat to the one w...
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The descriptions of the new species Cymbella balkii sp. nov. and C. yerlii sp. nov. were given in this study. The species were found in a karstic limnocrene spring which is one of the most important sources of Sakarya River. Cymbella... more
The descriptions of the new species Cymbella balkii sp. nov. and C. yerlii sp. nov. were given in this study. The species were found in a karstic limnocrene spring which is one of the most important sources of Sakarya River. Cymbella balkii sp. nov. is very similar to C. pervarians, C. simonsenii, C. percymbiformis, C. perparva, C. alpestris and C. vulgata. Among them, C. pervarians is the most similar taxon however, the former has higher stigmata number and larger valve than the latter. Cymbella yerlii sp. nov. is very similar to C. parva, C. perparva and C. parviformis are similar taxa. Among them, C. parva is the most similar taxon in all related ones with similar outline. However, length/width ratio is higher in C. yerlii than the other taxa.
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The diatoms have intricate silica‐based cell walls with multi‐scale patterns. High dynamic range (HDR) imaging is widely used to examine the three‐dimensional structure of diatoms for recovering the wide range of contrast and brightness.... more
The diatoms have intricate silica‐based cell walls with multi‐scale patterns. High dynamic range (HDR) imaging is widely used to examine the three‐dimensional structure of diatoms for recovering the wide range of contrast and brightness. In order to construct a HDR image of a diatom, multiple images of the specimen are taken at different exposure settings with bright or dark field microscopy. In the proposed method, multi‐scale decomposition based on nonsubsampled contourlet transform is adopted to separate the structured and detailed information of the HDR image. And then, by processing all layers independently, the tone‐mapped image is reconstructed to retain details present in the dark and light regions. Quantitative and qualitative analysis is performed in order to assess the performance of the proposed and seven existing tone‐mapping operators. In analysis, the study indicates that the proposed method enhances the diatom frustules to extract more details.
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The family of Bacillariaceae Ehrenberg is a group of well-known raphid diatoms, associated with water quality. Our current knowledge of the species diversity of this group in Turkey is still incomplete. There are three river basins in the... more
The family of Bacillariaceae Ehrenberg is a group of well-known raphid diatoms, associated with water quality. Our current knowledge of the species diversity of this group in Turkey is still incomplete. There are three river basins in the Kütahya region in Turkey, located in the eastern part of the country, including the Gediz, Sakarya and Susurluk basins, thus the region is rich in lotic waters. We present each taxon based on our observations of specimens collected in the Kütahya region. A total of 53 sites were surveyed in this study and a total of 65 taxa from Bacillariaceae were identified. Of these 65 taxa, 15 are recognized as the first records for Turkey. For each taxon, we indicate the reference(s) used for its identification. To facilitate the identification by others working on the Turkish freshwater diatom flora, we also present dimensions of the taxa identified, the distribution of each taxon in the Kütahya region, the distribution of each taxon in Turkey as well as one ...
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Disentangling the relative role of species sorting and dispersal limitation in biological communities has become one of the main issues for community ecologists and biogeographers. In this study, we analysed a data set of epiphytic... more
Disentangling the relative role of species sorting and dispersal limitation in biological communities has become one of the main issues for community ecologists and biogeographers. In this study, we analysed a data set of epiphytic diatoms comprising 34 lakes from six European countries. This data set covers a relatively large latitudinal gradient to elucidate which processes are affecting the distribution of diatom communities on a broad spatial extent. Our results show strong environmental effects on the composition of the diatom communities, while the spatial factor effects were weak, emphasising that compositional variation was mainly due to species turnover. Our data support information from the literature that local abiotic factors are the main predictors controlling the compositional variation of diatom assemblages in European shallow lakes. More specifically, changes in species composition were driven mainly by nutrient content in Northern Europe, whereas lakes located in Southern Europe were more affected by conductivity and lake depth. Our results solve pending questions in the spatial ecology of diatoms by proving that species turnover is stronger than nestedness at any spatial scale, and give support to the use of epiphytic diatoms as biological indicators for shallow lakes.
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Biblioteca de la Universidad Complutense de Madrid, Base de datos de artículos de revistas, ...
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Increased salt concentration is one of the most widespread problems affecting freshwater worldwide. Aquatic communities, and in particular periphytic diatoms, react to this alteration in water quality by modifying their structural... more
Increased salt concentration is one of the most widespread problems affecting freshwater worldwide. Aquatic communities, and in particular periphytic diatoms, react to this alteration in water quality by modifying their structural parameters and physiology at the individual level, which is commonly manifested by the appearance of teratological forms. The present work presents the results of an experimental laboratory study in which a biofilm grown on artificial substrates was subjected to a gradient of water conductivities for 4 weeks. The results show an increase in the number of deformed valves over time proportionally to the increase in conductivity for each experimental treatment. These effects are also verified by analyzing the concentration of chlorophyll-a in the experimental biofilms, which demonstrate a metabolic response to the induced osmotic stress. No changes were recorded; however, in species richness or diversity of taxa present in the treatments. Our results, therefore, confirm at the experimental level numerous previous field observations about the harmful effect of salinity on periphytic diatoms, and also their ability to reintegrate with the new stress conditions.
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The time required for diatom assemblages to integrate the abiotic variables of the aquatic environment has been subject of discussion for many years, with contrasting opinions as shown by field observations and experiments. Numerous... more
The time required for diatom assemblages to integrate the abiotic variables of the aquatic environment has been subject of discussion for many years, with contrasting opinions as shown by field observations and experiments. Numerous diatom-based water quality indices are being used in the bioassessment of freshwaters; one of the most widely used (Specific Polluosensitivity Index or SPI) is compared in this study with water quality status as measured by the Water Quality Index (WQI) obtained from limnological parameters measured at 37 fluvial stations belonging to the Duero Basin (NW Spain). The correlation existing between both metrics was determined using different time lags between water and diatom sample collection. Results show that the correlation coefficient increases as the time gap decreases, but is maximal when comparing WQI scores measured one month before diatom sampling. We thus confirm the initial hypothesis that diatom indices actually indicate past (1 month ago) and not current water conditions in rivers. The practical consequences of this finding are briefly discussed.
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Over the past few years, the construction industry has sought to be more sustainable through use of more economically responsible materials and the use of environmentally friendly techniques such as bio-remediation. One promising area in... more
Over the past few years, the construction industry has sought to be more sustainable through use of more economically responsible materials and the use of environmentally friendly techniques such as bio-remediation. One promising area in this regard is that of surface treatments, particularly bio-repair techniques, to reduce the deterioration suffered by cement-based materials as a result of environmental conditions. This study presents original work on the use of silicaceous biodeposition by diatoms as a waterproofing surface treatment for recycled concrete. A recycled concrete mix containing a 50% substitution of recycled aggregates (RA) was used as a test substrate and the effectiveness of the bio-treatment was assessed using four different tests: capillary absorption, high-pressure water penetration, low-pressure water absorption and also characterised the biodeposited layer using SEM. Results demonstrate reductions of up to 33% in the capillary absorption test, while high-pressure water penetration decreased by 54.7%, compared to controls. In addition, Karsten tube tests showed low-pressure water absorption was delayed by up to 436 times relative to control samples. In combination these tests confirm the efficacy of diatom biodeposition as a protective surface treatment for cement-based construction materials.
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This work studies the behaviour of diatoms in artificial culture envi- ronments and analyses the biodeposition of diatom frustules in different sizes of mixed recycled aggregates. In order to be able to use this biodeposition as a sur-... more
This work studies the behaviour of diatoms in artificial culture envi- ronments and analyses the biodeposition of diatom frustules in different sizes of mixed recycled aggregates. In order to be able to use this biodeposition as a sur- face treatment and improve the properties of this material for its effective use in recycled concrete. Surface analyses show that the density of diatoms in biofilm formation depends on the aggregate size, being better in smaller aggregates of 4– 6.3 mm diameter. However, the diversity of diatoms is higher in aggregates with fractions of 8–12.5 mm. The combination of these tests demonstrates that diatom biodeposition is feasible in artificial environments for possible use as a protective surface treatment of cement-based building materials.
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Typology systems are frequently used in applied and fundamental ecology and are relevant for environmental monitoring and conservation. They aggregate ecosystems into discrete types based on biotic and abiotic variables, assuming that... more
Typology systems are frequently used in applied and fundamental ecology and are relevant for environmental monitoring and conservation. They aggregate ecosystems into discrete types based on biotic and abiotic variables, assuming that ecosystems of the same type are more alike than ecosystems of different types with regard to a specific property of interest. We evaluated whether this assumption is met by the Broad River Types (BRT), a recently proposed European river typology system, that classifies river segments based on abiotic variables, when it is used to group biological communities. We compiled data on the community composition of diatoms, fishes, and aquatic macrophytes throughout Europe and evaluated whether the composition is more similar in site groups with the same river type than in site groups of different river types using analysis of similarities, classification strength, typical species analysis, and the area under zeta diversity decline curves. We compared the performance of the BRT with those of four region-based typology systems, namely, Illies Freshwater Ecoregions, the Biogeographic Regions, the Freshwater Ecoregions of the World, and the Environmental Zones, as well as spatial autocorrelation (SA) classifications.
All typology systems received low scores from most evaluation methods, relative to predefined thresholds and the SA classifications. The BRT often scored lowest of all typology systems. Within each typology system, community composition overlapped considerably between site groups defined by the types of the systems. The overlap tended to be the lowest for fishes and between Illies Freshwater Ecoregions.
In conclusion, we found that existing broad-scale river typology systems fail to delineate site groups with distinct and compositionally homogeneous communities of diatoms, fishes, and macrophytes. A way to improve the fit between typology systems and biological communities might be to combine segment-based and region-based typology systems to simultaneously account for local environmental variation and historical distribution patterns, thus potentially improving the utility of broad-scale typology systems for freshwater biota.
All typology systems received low scores from most evaluation methods, relative to predefined thresholds and the SA classifications. The BRT often scored lowest of all typology systems. Within each typology system, community composition overlapped considerably between site groups defined by the types of the systems. The overlap tended to be the lowest for fishes and between Illies Freshwater Ecoregions.
In conclusion, we found that existing broad-scale river typology systems fail to delineate site groups with distinct and compositionally homogeneous communities of diatoms, fishes, and macrophytes. A way to improve the fit between typology systems and biological communities might be to combine segment-based and region-based typology systems to simultaneously account for local environmental variation and historical distribution patterns, thus potentially improving the utility of broad-scale typology systems for freshwater biota.
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Lake Salda has a unique environment due to the presence of hydromagnesite stromatolites. Samples collected from the stromatolites contained a new diatom species, Gomphonella saldanensis sp. nov., which is described based on light and... more
Lake Salda has a unique environment due to the presence of hydromagnesite stromatolites. Samples collected from the stromatolites contained a new diatom species, Gomphonella saldanensis sp. nov., which is described based on light and scanning electron microscopy. The main character of the taxon is its linear-lanceolate outline with a rostrate headpole and narrowly rounded footpole. The striae are strongly radiate mid-valve, becoming parallel to slightly radiate towards the poles. Elliptical Fourier and Linear Discriminant analyses indicate that there are different shape forms within the same taxon. Based on LM observations, G. saldanensis is similar to Gomphonema lagerheimii f. simplex, G. geisslerae, Gomphonella calcarea, G. olivacea, G. acsiae and G. coxiae. However, G. lagerheimii f. simplex differs with slightly radiate striae throughout the valve. Gomphonella geisslerae has a slightly undulate raphe and linear apices. Larger specimens of G. acsiae are lanceolate, clavate in smaller specimens. The remaining Gomphonella species, G. calcarea, G. coxiae and G. olivacea have broader outlines and lower stria densities.
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Diatoms are microalgae, known to present several characteristics that make them excellent bioindicators. In this study, we analyzed the epiphytic diatom communities of ponds, with the aim of exploring the genetic variability explained by... more
Diatoms are microalgae, known to present several characteristics that make them excellent bioindicators. In this study, we analyzed the epiphytic diatom communities of ponds, with the aim of exploring the genetic variability explained by physical, chemical or geographical variables. We selected 77 lakes within the Spanish part of the Duero River Basin characterized by wide chemical variability. In each lake, physical parameters were measured in situ and water samples were taken to determine nutrient levels in the laboratory. Diatom communities were collected and identified by DNA-metabarcoding, amplifying a genetic barcode of rbcL gene. We analyzed the phylogenetic signal for several environmental parameters at the genus level for the three most representative genera of these lakes. Our results indicate significant phylogenetic signals that differ from a genus to another. Processes related to spatial scales appear to be the main predictors controlling the genetic diversity of diatom communities in these ponds, with genetic variants differing among geographical areas for a given species. These molecular studies confirm the enormous diversity present in the diatom communities that inhabit these ecosystems, but further research is needed to apply diatom-based techniques in ponds monitoring or conservation programs. Our results reinforce the view that considering not only morphological but also molecular and ecological characters are necessary to describe new living diatom species, whenever possible, especially given the high number of species described each year.
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This study addresses the challenges of sustainability and the implementation of a circular economy in the construction and maintenance of concrete structures used in clean-water applications. Specifically, it examines the use of an... more
This study addresses the challenges of sustainability and the implementation of a circular economy in the construction and maintenance of concrete structures used in clean-water applications. Specifically, it examines the use of an innovative surface treatment based on a biofilm comprising diatom biosilica deposition as a waterproofing agent and surface pore sealant to improve the longevity of recycled concrete. To this end biofilmtreated and untreated (control) samples of a concrete mix containing 50% recycled aggregates were subject to four performance tests directed at assessing the durability of concrete structures under environmental conditions: resistance to carbonation, freeze-thaw durability, resistance to water penetration, and electrical resistivity as an indicator of the corrosion resistance of concrete. In addition, the protective biofilm was characterised using SEM. Results suggest that the biogenic silica surface treatment significantly improves the durability of recycled concrete, in particular, for treated compared to untreated samples there was a 56 % reduction of the carbonation front, 26% lower mass loss in freeze-thaw cycles, 57% reduction in the water penetration front under pressure, and 44% higher electrical resistivity. Together these findings confirm that the biofilm used in this study constitutes an effective treatment to improve the properties of recycled concrete and ensure its durability, particularly when used in the construction of structures in contact with constant water fluctuations.
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Kaçkar Mountains is located in the Eastern Black Sea Region in Türkiye. The mountainous area includes granite and volcanic rocks influencing water conditions. Moçar Lake is located at 40°42'35'' N and 40°54'51'' E in the Verçenik Valley... more
Kaçkar Mountains is located in the Eastern Black Sea Region in Türkiye. The mountainous area includes granite and volcanic rocks influencing water conditions. Moçar Lake is located at 40°42'35'' N and 40°54'51'' E in the Verçenik Valley with an altitude of 3.060 m. a.s.l. The samples were collected in July 2015 from epilithic and epipelic substrata. Epilithic samples were collected using a toothbrush and epipelic samples collected using a pipette. The description of the new species Sellaphora lucectoriana sp. nov. were given in this study. Valve apices and striae density are diagnostic characters for S. lucectoriana. Sellaphora hentiensis (Kulikovskiy, Lange-Bertalot, A
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Aim Understanding the roles of deterministic and stochastic processes in community assembly is essential for gaining insights into the biogeographical patterns of biodiversity. However, the way community assembly processes operate is... more
Aim
Understanding the roles of deterministic and stochastic processes in community assembly is essential for gaining insights into the biogeographical patterns of biodiversity. However, the way community assembly processes operate is still not fully understood, especially in oceanic islands. In this study, we examine the importance of assembly processes in shaping diatom communities in islands and continents, while also investigating the influence of climate and local water chemistry variables on species distributions.
Location
Global.
Taxon
Stream benthic diatoms.
Methods
We used diatom datasets from five continents and 19 islands and applied beta diversity analyses with a null model approach and hierarchical joint species distribution modelling. To facilitate comparisons with continents, we used continental area equivalents (CAEs), which represent continental subsets with comparable areas and the same number of study sites as their corresponding islands counterparts.
Results
We found that homogeneous selection (i.e., communities being more similar than the random expectation) was the dominant assembly process within islands whereas stochastic processes tended to be more important within continents. In addition, assembly processes were influenced by study scale and island isolation. Climatic variables showed a greater influence on species distribution than local factors. However, in islands, local environmental variables had a greater impact on the distributions of unique taxa as opposed to non-unique taxa.
Main Conclusions
We observed that the assembly processes of diatom communities were complex and influenced by a combination of deterministic and stochastic forces, which varied across spatial scales. In islands, there was no universal pattern of assembly processes, given that their influence depends on abiotic conditions such as area, isolation, and environmental heterogeneity. In addition, the sensitivity of species occurring uniquely in islands to local environmental variables suggests that they are perhaps less vulnerable to climatic changes but may be more influenced by changes in local physicochemistry.
Understanding the roles of deterministic and stochastic processes in community assembly is essential for gaining insights into the biogeographical patterns of biodiversity. However, the way community assembly processes operate is still not fully understood, especially in oceanic islands. In this study, we examine the importance of assembly processes in shaping diatom communities in islands and continents, while also investigating the influence of climate and local water chemistry variables on species distributions.
Location
Global.
Taxon
Stream benthic diatoms.
Methods
We used diatom datasets from five continents and 19 islands and applied beta diversity analyses with a null model approach and hierarchical joint species distribution modelling. To facilitate comparisons with continents, we used continental area equivalents (CAEs), which represent continental subsets with comparable areas and the same number of study sites as their corresponding islands counterparts.
Results
We found that homogeneous selection (i.e., communities being more similar than the random expectation) was the dominant assembly process within islands whereas stochastic processes tended to be more important within continents. In addition, assembly processes were influenced by study scale and island isolation. Climatic variables showed a greater influence on species distribution than local factors. However, in islands, local environmental variables had a greater impact on the distributions of unique taxa as opposed to non-unique taxa.
Main Conclusions
We observed that the assembly processes of diatom communities were complex and influenced by a combination of deterministic and stochastic forces, which varied across spatial scales. In islands, there was no universal pattern of assembly processes, given that their influence depends on abiotic conditions such as area, isolation, and environmental heterogeneity. In addition, the sensitivity of species occurring uniquely in islands to local environmental variables suggests that they are perhaps less vulnerable to climatic changes but may be more influenced by changes in local physicochemistry.
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Research Interests: Environmental Science, Carbon, Bioremediation, Environmental Chemistry, Medicine, and 15 moreMultidisciplinary, Animal Husbandry, Nitrification, Animals, Bacteria, Nitrogen, Biomass production, Environmental Conditions, Empirical evidence, Dissolved Oxygen, Long Term, Environment, High rate algal pond, Bioresource technology, and Climatic condition
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Cyanobacteria, an abundant source of natural products as biomedical compounds have emerged as a novel resource for the progression of synthetic analogs. Due to the rise of antibiotic resistance, there is a need for new medications and... more
Cyanobacteria, an abundant source of natural products as biomedical compounds have emerged as a novel resource for the progression of synthetic analogs. Due to the rise of antibiotic resistance, there is a need for new medications and cyanobacteria-derived compounds with promising antimicrobial, immunosuppressant, anti-carcinoma, antiviral and protease inhibition activity are a potent option for new therapeutics. Current research is focused on the exploitation of cyanobacteria for the production of bioactive metabolites. Screening of cyanobacteria for pharmaceutically active compounds has received increasing attention; overall, there is a promising outlook that cyanobacterial secondary metabolites will become alternatives for the development of new and more effective medications.
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Today, agro-industry is a key economic sector worldwide with a large associated generation of wastewaters. These wastewaters entail a hazard to the environment and a waste of valuable organic matter and nutrients. The use of microalgae to... more
Today, agro-industry is a key economic sector worldwide with a large associated generation of wastewaters. These wastewaters entail a hazard to the environment and a waste of valuable organic matter and nutrients. The use of microalgae to support an efficient and low cost treatment of agro-industrial wastewaters along with a sustainable resource recovery has attracted an increasing attention over the past decades. This book chapter will critically discuss the fundamentals of algal-bacterial symbiosis and photobioreactor design in the context of wastewater treatment. The current challenges in microalgae harvesting and biomass valorization in the form of feedstock for the production of biofertilizers, fish feed, and biogas will be also presented along with a critical evaluation of the sustainability of the process. Finally, the future trends in the field of photosynthetic treatment of agro-industrial wastewater will be outlined.
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Correct identification of diatom taxa is indispensable for diatom-based water quality studies, as well as for biotechnological applications. Biological applications of taxonomy include the identification of taxa from particular specimens.... more
Correct identification of diatom taxa is indispensable for diatom-based water quality studies, as well as for biotechnological applications. Biological applications of taxonomy include the identification of taxa from particular specimens. In this regard, identification keys, that use a predetermined set of characters to identify a given individual, are not commonly employed by diatom specialists due to the extreme biological diversity found in this group of microalgae. This chapter reviews previous attempts of using taxonomic keys for diatom identification, highlighting the pros and cons of the use of this and similar methods. The main morphological features found in common freshwater diatom genera are briefly presented, together with an account of the historical development of technologies used for species description.
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This chapter introduces the antecedents, motivation, and necessity of the use of automatic identification methods in diatom taxonomy. Expert biologists have a repetitive and laborious identification mission. The principal taxonomic... more
This chapter introduces the antecedents, motivation, and necessity of the use of automatic identification methods in diatom taxonomy. Expert biologists have a repetitive and laborious identification mission. The principal taxonomic features used to describe and classify diatoms relate to the morphology and texture of frustule. Classical taxonomic diagnosis is carried out by means of identification keys or by visual comparison with respect to standard preparations or reference iconographies. Automatic diatom identification remains an open challenge because, for instance, many diatoms that have been known by the same species for decades have subsequently been split into different species, while on the other hand the emergence of new species is continuous. The very promising results of the new deep learning techniques together with the development of new optical devices in microscopy allow to predict a significant advance in the field.
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Diatom identification must consider the large variability in both morphological and morphometric features, characteristic of this group of microorganisms. This chapter describes variations in shape/size observed in diatom populations... more
Diatom identification must consider the large variability in both morphological and morphometric features, characteristic of this group of microorganisms. This chapter describes variations in shape/size observed in diatom populations either as a consequence of their particular asexual reproductive cycle or induced by environmental conditions. Concerning this latter, teratological diatoms are commonly associated with a variety of environmental stressors, particularly the presence of micropollutants in the aquatic ecosystem, such as heavy metals. We evidence an overestimation of water quality conditions caused by overriding deformed individuals in diatom-based biomonitoring studies. It can be shown that normal and aberrant forms of the same taxon differ in autecological preferences. Finally, we advise on a critical issue in the description of diatom specimens, that is, the sample size on which morphometric ranges should be provided. The section concludes with some recommendations in this regard.
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Diatom metrics methods are becoming important tools for the assessment of environmental conditions in aquatic systems. Diatoms have several advantages as bioindicators: their ubiquitous distribution across world aquatic environments,... more
Diatom metrics methods are becoming important tools for the assessment of environmental conditions in aquatic systems. Diatoms have several advantages as bioindicators: their ubiquitous distribution across world aquatic environments, their ability to integrate multiple water quality features, and the relatively simple and standardized sampling and preparation methods. To date, several diatom indices have been developed, most of which are general pollution indices, especially indicative of eutrophication and organic pollution. This chapter reviews the literature concerning diatom-based analyses for biomonitoring purposes, with a first overview on available methods (microscopy-based, automatic identification, and DNA barcoding), and an account on bioassessment tools using phytobenthos in EU countries, with a special focus on the Spanish experience.