Saúl Blanco | University of León - Universidad de León (original) (raw)
Books by Saúl Blanco
Diatoms are commonly used in environmental assessments to detect pollution and eutrophication. Th... more Diatoms are commonly used in environmental assessments to detect pollution and eutrophication. The specific pollution sensitivity index (SPI) is one of the most frequently used indices, which assigns scores to diatom taxa based on their sensitivity to pollution. The study analyzed diatom communities in the Duero River basin in Spain to examine the relationship between SPI scores and various limnological variables. A GLM model showed that phosphates, nitrites, and water temperature were the main factors explaining SPI variability. The study also reviews previous results using SPI for water quality monitoring in different world regions, highlighting the role of nutrients in general as major drivers of SPI values worldwide. Overall, the findings reinforce the reliability of SPI as a metric for biological monitoring in various watercourses.
Cuatro Cienegas is a natural geopark that exhibits a vast reservoir of geological, geochemical an... more Cuatro Cienegas is a natural geopark that exhibits a vast reservoir of geological, geochemical and geobiological diversity, including shallow-water microbial carbonates with clotted micrite textures known as thrombolites. Thrombolites mainly occur as domes and massive irregular carbonates along the margins of Rio Mezquites in Cuatro Cienegas, northern Mexico. Because their clotted textures result from diverse abiotic and biotic interactions at the microbial–mineral interface, the formation of clots in thrombolites continues to be a contentious issue. Through a petrographic, scanning electron microscopy and bulk biogeochemical analysis, this study investigated the role of endolithic cyanobacteria in the generation of thrombolitic clots. Their microclotted fabric is characterized by 50 to 200 μm peloidal clots, pores, fenestrae, crevices and cavities as main components. Thrombolites also contain microbial microstructures, some of them interpreted as the endolithic contribution to the genesis of clotted micrite. Thrombolites and associated fresh microbial mats are composed of cyanobacteria, green algae and diatoms. Petrography and cast-embedded scanning electron microscopy micrographs also show the presence of filamentous endolithic cyanobacteria inside the thrombolitic framestone. The geochemical bulk characterization for carbon and oxygen isotopes shows average values of −0.7‰ Vienna PeeDee Belemnite and −8.0‰ Vienna PeeDee Belemnite, respectively. The organic matter preserved in their mineral matrix and associated microbial mats indicated the putative presence of cyanobacterial hopanoids. The high diversity of peloids and the microboring evidence, together with observed microstructures, suggest that clots may also form by the concurrent precipitation and dissolution of the thrombolites. Among the known sources of peloidal clots, microbial boring may be an additional micrite source for clot formation. Microbial carbonate dissolution may also promote heterogenous lithification by hydration and dehydration cycles. Thrombolites reflect complex systems due to concurrent interactions among producers (phototrophs), consumers (small invertebrates), mineralization (carbonate precipitation induced by phototrophs) and endolithic dissolution. The microstructures inside thrombolites, in conjunction with biogeochemical attributes of bulk thrombolites, may provide unambiguous sedimentary biosignatures.
High-resolution images of phytoplankton cells such as diatoms or desmids, which are useful for mo... 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.
Las diatomeas son un grupo de algas microsc{\'{o}}picas extremadamente diversificado que viven en... 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.
This catalogue aims to compile the information available on continental (recent and fossil) diato... 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.
The authors present a taxonomic study of benthic diatoms collected from coastal rocks in seve... 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.
En esta obra se recogen los 200 taxones de diatomeas (pertenecientes a 60 géneros distintos) más ... 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).
This thesis is based on the following papers: • Blanco S, Bécares E, Fernández-Aláez M 2008. Effi... 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
Para facilitar y homogeneizar el tratamiento y la interpretación de la información generada en la... 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.
"The Duero River Basin, with an area of 97290 km2 and more than 40000 km of streams, is the large... 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."
Papers by Saúl Blanco
For the first time, we propose a diatom-based biomonitoring index (BDIAR) for Algerian Rivers. BD... more For the first time, we propose a diatom-based biomonitoring index (BDIAR) for Algerian Rivers. BDIAR is based on water conductivity and diatom autecological profiles. Our study was conducted along the Coastal Central Constantine watershed, from which 78 samples of diatoms and water were collected. Weighted averaging method was used to determine the diatom autecological parameters (optimum and tolerance), estimated for157 diatom species for the first time in our country. There was a significant positive correlation between measured and expected conductivity values of sampling sites based on their diatom composition (r2 = 0.64, P = 0.0001). Linear regression statistics revealed a strong correlation between BDIAR and conductivity (Pearson correlation P = 0.0001). Two similar methods (the Index for Soda Pans DISP and Carayon Index) albeit useful for inferring conductivity values were less accurate (P = 0.08 and 0.03 respectively). χ2 and κ statistics demonstrated that using our metric yields a correct site classification in water conductivity classes. The BDIAR is not limited to Algerian streams; it can be applied in biomonitoring programs for all freshwater systems with similar ecological conditions after the reference status determined. This adaptability enhances its potential for widespread use in monitoring and managing water quality across various regions.
This study evaluates the effectiveness of improving the durability of recycled aggregate concrete... more This study evaluates the effectiveness of improving the durability of recycled aggregate concrete (RAC) through the controlled deposition of biogenic silica (SiO2). This process is optimised by growing diatoms in two artificial environments as a mean to produce a protective coating. Concrete samples with protective bio-coatings grown in two different environments were tested for durability against uncoated control samples and results suggest that the biocoating provides significant benefits. Increases of 30–50% in ultrasonic pulse velocity were demonstrated for bio-coated concrete samples suggesting that the diatom treatment produces surface densification thus increasing the mechanical strength of bio-coated concrete. Tests of chloride ion diffusion and resistance to freeze-thaw cycles showed reductions in permeability due to the biocoating of 29–34% and 34–45%, for each test respectively. Improvements in corrosion resistance were also shown in resistivity tests. In addition, SEM and BSEM microscopy provides evidence to support the conclusions of physical tests: diatoms migrate to fill surface pores and micro-cracks reducing the porosity of the concrete’s surface matrix resulting in surface densification and decreased permeability.
The increasing generation of construction and demolition waste poses an environmental challenge. ... more The increasing generation of construction and demolition waste poses an environmental challenge. In this study, the use of recycled concretes is proposed as a possible solution, reducing the extraction of natural resources and minimising the accumulation of waste in landfills. To ensure the durability and strength of this type of recycled concrete, two diatom culture techniques were developed in controlled environments to promote the bio-deposition of biogenic silica on the surface concrete. Through the resulting protective biofilm, diatoms decreased the capillary absorption and improved the impermeability of concrete to water and gases, such as CO2. Furthermore, these contributed to an increased mechanical strength of the concrete and a positive morphological modification of its surface by densifying and sealing surface pores. These results support the potential of diatoms as an effective solution to improve the properties and durability of recycled concrete.
Increased water conductivity levels have been proposed as a key factor to explain the occurrence ... more Increased water conductivity levels have been proposed as a key factor to explain the occurrence of teratological forms in freshwater diatom assemblages. The current study aimed to carry out an experiment on a laboratory scale to assess the response of periphytic diatoms to artificially increased salinity levels. The obtained results show that: a) the proportion of aberrant cells increased in high conductivity treatments, b) developed teratologies were preserved in diatom populations even after being translocated to normal conditions, and c) the degree of valve outline deformation in the dominant species was proportional to the induced water conductivity. All these data support previous field observations that linked high electrolyte content and the abundance of aberrant cells among microalgal communities in continental aquatic ecosystems.
Nitrous oxide (N2O) emissions in High Rate Algal Ponds (HRAP) can negatively affect the sustainab... more Nitrous oxide (N2O) emissions in High Rate Algal Ponds (HRAP) can negatively affect the sustainability of algal-bacterial processes. N2O emissions from a pilot HRAP devoted to biogas upgrading and digestate treatment were herein monitored for 73 days. The influence of the pH (7.5, 8.5, and 9.5), nitrogen sources (100 mg L−1 of N–NO2-, N–NO3-, and N–NH4+) and illumination on N2O emissions from the algal-bacterial biomass of the HRAP was also assessed in batch tests. Significantly higher N2O gas concentrations of 311.8 ± 101.1 ppmv were recorded in the dark compared to the illuminated period (236.9 ± 82.6 ppmv) in the HRAP. The batch tests revealed that the highest N2O emission rates (49.4 mmol g−1 TSS·h−1) occurred at pH 8.5 in the presence of 100 mg N–NO2-/L under dark conditions. This study revealed significant N2O emissions in HRAPs during darkness.
The objective of this study was to explore the environmental factors having the greatest influenc... more The objective of this study was to explore the environmental factors having the greatest influence on the distribution and abundance of epipelic diatom species in different wetlands in southern Spain. We previously defined four groups of conductivity categories: fresh (< 0.8 mS cm−1), oligosaline (< 8 mS cm−1), mesosaline (8–30 mS cm−1) and eusaline (> 30 mS cm−1). A dbRDA analysis performed on a subset of 36 of the 53 wetlands, using a total of 25 environmental variables, showed that five environmental variables (conductivity, pH, wetland area, silicates, and total suspended solids) were the best explanatory variables for the diatom assemblage, with conductivity being the main explanatory variable. Nonmetric multidimensional scaling (nMDS) analysis performed on the set of 53 wetlands revealed significant differences in diatom composition among the four conductivity groups. The key species in the eusaline group were Tryblionella pararostrata, Halamphora sp.1 and Cocconeis euglypta, whereas in the mesosaline and oligosaline group, these were Navicula veneta, Tryblionella hungarica and Nitzschia inconspicua. Finally, in the fresh group dominated Achnanthidium minutissimum, Navicula veneta and Gomphonema exilissimum. This study on epipelic diatoms can therefore contribute to the knowledge of these organisms in a European region with a high diversity of wetland typologies.
The initial valves of two Cymbella species are observed under a scanning electron microscope, and... more The initial valves of two Cymbella species are observed under a scanning electron microscope, and the perizonium ultrastructure of Cymbella is revealed for the first time. The perizonium is composed of alternate nodes and internodes and lacks transverse perizonium bands. Four new species, Cymbella apiculatophora sp. nov., C. hunanensis sp. nov., C. juglandis sp. nov. and C. menyuanensis sp. nov., are described using light and scanning electron microscopy based on epilithon samples collected from rivers in Hunan and Qinghai Provinces, China. Cymbella menyuanensis is a typical Cymbella species that closely resembles species in the group around C. cymbiformis Agardh, the type species of the genus. Cymbella apiculatophora is similar to C. sinensis Metzeltin & Krammer, while Cymbella hunanensis is closer to the C. hustedtii Krasske group. The last species, C. juglandis, has a cymbelloid valve outline, an obscured intermissio, internal occlusions of the areolae, dorsally deflected distal raphe fissures and a divided apical pore field at each apex, and it does not appear to belong to any group. In addition, new observations on C. cf. excisiformis Krammer and C. hustedtii are reported. The current concept of the genus Cymbella does not represent a monophyletic group as shown by molecular phylogenetic analyses. However, these analyses are still at the preliminary stage and are not yet sufficient to support a complete revision of the genus. Thus, although extremely diverse ultrastructural features are observed in the six Cymbella species investigated in this paper, we prefer to keep them within Cymbella at this moment for the sake of nomenclatural stability.
Aim Understanding the roles of deterministic and stochastic processes in community assembly is es... 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.
Interspecific abundance-occupancy relationships (AOR) have been addressed as one of the most impo... more Interspecific abundance-occupancy relationships (AOR) have been addressed as one of the most important questions regarding the spatial ecology of diatoms. Whereas positive interspecific AOR is a common feature of ecological communi- ties, little is known about its causes and consequences. Studies to date confirm that AOR depends mostly on the ecological features exhibited by the species pool ana- lyzed, particularly niche characteristics and habitat guilds. The present study aims to test the persistence of such patterns using pond diatoms at a mesoscale level. Epiphytic and planktonic diatoms were collected in 29 shallow ponds throughout the Northern Iberian Plateau. Analysis of covariance (ANCOVA) tests revealed contrasting patterns when both assemblages are compared; for a given abundance level, epiphytic species were present in twice as many locations as planktonic ones, with noticeable effects also attributable to cell biovolume and motile guild. Contrary to our expectations, niche characteristics, measured in terms of species sensitivity and indicator value with respect to abiotic variables, had a negligible effect on AOR models. The consequences of such results are briefly discussed at a theoretical level.
Aim To evaluate the patterns of stream diatom beta diversity in islands versus continents across ... more Aim To evaluate the patterns of stream diatom beta diversity in islands versus continents across scales, to relate community similarities with spatial and environmental distances and to investigate the role of island characteristics in shaping insular diatom beta diversity. Location Africa, America, Europe and the Pacific. Time Period Present. Major Taxa Studied Stream diatoms. Methods We compared diatom beta diversity between islands and continents at large scales (within biogeographic regions) in two study regions (America and Europe) and at small scales (within islands/equivalent areas in continents) in three regions (Africa, America and Europe) partitioning beta diversity into turnover and nestedness components. We used a partial Mantel test and distance–decay curves to assess how diatom beta diversity on islands and continents is affected by spatial and environmental distances. Finally, using island data from all four regions, we evaluated the relationship between island beta diversity and island latitude, area, age and isolation using linear models. Results At large scales, mean dissimilarities were higher on islands than in continents in Europe but lower in America. At smaller scales, the differences varied mostly depending on island isolation. Beta diversity was mainly caused by species turnover. Partial Mantel test and distance–decay curves revealed that spatial and environmental distances shaped diatom beta diversity at large, but not at small scales. Moreover, diatom beta diversity on islands was affected by island latitude, age and isolation, but not by island area. Main Conclusions Diatom beta diversity on islands versus continents and its responses to spatial and environmental factors are scale and region dependent. Incomplete colonisation, evolutionary processes and environmental filtering likely contribute to insular beta diversity, which further varies with island latitude, age and isolation. This study sheds new light on beta diversity of microorganisms on islands and suggests that beta diversity should be explicitly considered in island biogeographical research.
Diatoms are commonly used in environmental assessments to detect pollution and eutrophication. Th... more Diatoms are commonly used in environmental assessments to detect pollution and eutrophication. The specific pollution sensitivity index (SPI) is one of the most frequently used indices, which assigns scores to diatom taxa based on their sensitivity to pollution. The study analyzed diatom communities in the Duero River basin in Spain to examine the relationship between SPI scores and various limnological variables. A GLM model showed that phosphates, nitrites, and water temperature were the main factors explaining SPI variability. The study also reviews previous results using SPI for water quality monitoring in different world regions, highlighting the role of nutrients in general as major drivers of SPI values worldwide. Overall, the findings reinforce the reliability of SPI as a metric for biological monitoring in various watercourses.
Cuatro Cienegas is a natural geopark that exhibits a vast reservoir of geological, geochemical an... more Cuatro Cienegas is a natural geopark that exhibits a vast reservoir of geological, geochemical and geobiological diversity, including shallow-water microbial carbonates with clotted micrite textures known as thrombolites. Thrombolites mainly occur as domes and massive irregular carbonates along the margins of Rio Mezquites in Cuatro Cienegas, northern Mexico. Because their clotted textures result from diverse abiotic and biotic interactions at the microbial–mineral interface, the formation of clots in thrombolites continues to be a contentious issue. Through a petrographic, scanning electron microscopy and bulk biogeochemical analysis, this study investigated the role of endolithic cyanobacteria in the generation of thrombolitic clots. Their microclotted fabric is characterized by 50 to 200 μm peloidal clots, pores, fenestrae, crevices and cavities as main components. Thrombolites also contain microbial microstructures, some of them interpreted as the endolithic contribution to the genesis of clotted micrite. Thrombolites and associated fresh microbial mats are composed of cyanobacteria, green algae and diatoms. Petrography and cast-embedded scanning electron microscopy micrographs also show the presence of filamentous endolithic cyanobacteria inside the thrombolitic framestone. The geochemical bulk characterization for carbon and oxygen isotopes shows average values of −0.7‰ Vienna PeeDee Belemnite and −8.0‰ Vienna PeeDee Belemnite, respectively. The organic matter preserved in their mineral matrix and associated microbial mats indicated the putative presence of cyanobacterial hopanoids. The high diversity of peloids and the microboring evidence, together with observed microstructures, suggest that clots may also form by the concurrent precipitation and dissolution of the thrombolites. Among the known sources of peloidal clots, microbial boring may be an additional micrite source for clot formation. Microbial carbonate dissolution may also promote heterogenous lithification by hydration and dehydration cycles. Thrombolites reflect complex systems due to concurrent interactions among producers (phototrophs), consumers (small invertebrates), mineralization (carbonate precipitation induced by phototrophs) and endolithic dissolution. The microstructures inside thrombolites, in conjunction with biogeochemical attributes of bulk thrombolites, may provide unambiguous sedimentary biosignatures.
High-resolution images of phytoplankton cells such as diatoms or desmids, which are useful for mo... 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.
Las diatomeas son un grupo de algas microsc{\'{o}}picas extremadamente diversificado que viven en... 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.
This catalogue aims to compile the information available on continental (recent and fossil) diato... 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.
The authors present a taxonomic study of benthic diatoms collected from coastal rocks in seve... 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.
En esta obra se recogen los 200 taxones de diatomeas (pertenecientes a 60 géneros distintos) más ... 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).
This thesis is based on the following papers: • Blanco S, Bécares E, Fernández-Aláez M 2008. Effi... 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
Para facilitar y homogeneizar el tratamiento y la interpretación de la información generada en la... 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.
"The Duero River Basin, with an area of 97290 km2 and more than 40000 km of streams, is the large... 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."
For the first time, we propose a diatom-based biomonitoring index (BDIAR) for Algerian Rivers. BD... more For the first time, we propose a diatom-based biomonitoring index (BDIAR) for Algerian Rivers. BDIAR is based on water conductivity and diatom autecological profiles. Our study was conducted along the Coastal Central Constantine watershed, from which 78 samples of diatoms and water were collected. Weighted averaging method was used to determine the diatom autecological parameters (optimum and tolerance), estimated for157 diatom species for the first time in our country. There was a significant positive correlation between measured and expected conductivity values of sampling sites based on their diatom composition (r2 = 0.64, P = 0.0001). Linear regression statistics revealed a strong correlation between BDIAR and conductivity (Pearson correlation P = 0.0001). Two similar methods (the Index for Soda Pans DISP and Carayon Index) albeit useful for inferring conductivity values were less accurate (P = 0.08 and 0.03 respectively). χ2 and κ statistics demonstrated that using our metric yields a correct site classification in water conductivity classes. The BDIAR is not limited to Algerian streams; it can be applied in biomonitoring programs for all freshwater systems with similar ecological conditions after the reference status determined. This adaptability enhances its potential for widespread use in monitoring and managing water quality across various regions.
This study evaluates the effectiveness of improving the durability of recycled aggregate concrete... more This study evaluates the effectiveness of improving the durability of recycled aggregate concrete (RAC) through the controlled deposition of biogenic silica (SiO2). This process is optimised by growing diatoms in two artificial environments as a mean to produce a protective coating. Concrete samples with protective bio-coatings grown in two different environments were tested for durability against uncoated control samples and results suggest that the biocoating provides significant benefits. Increases of 30–50% in ultrasonic pulse velocity were demonstrated for bio-coated concrete samples suggesting that the diatom treatment produces surface densification thus increasing the mechanical strength of bio-coated concrete. Tests of chloride ion diffusion and resistance to freeze-thaw cycles showed reductions in permeability due to the biocoating of 29–34% and 34–45%, for each test respectively. Improvements in corrosion resistance were also shown in resistivity tests. In addition, SEM and BSEM microscopy provides evidence to support the conclusions of physical tests: diatoms migrate to fill surface pores and micro-cracks reducing the porosity of the concrete’s surface matrix resulting in surface densification and decreased permeability.
The increasing generation of construction and demolition waste poses an environmental challenge. ... more The increasing generation of construction and demolition waste poses an environmental challenge. In this study, the use of recycled concretes is proposed as a possible solution, reducing the extraction of natural resources and minimising the accumulation of waste in landfills. To ensure the durability and strength of this type of recycled concrete, two diatom culture techniques were developed in controlled environments to promote the bio-deposition of biogenic silica on the surface concrete. Through the resulting protective biofilm, diatoms decreased the capillary absorption and improved the impermeability of concrete to water and gases, such as CO2. Furthermore, these contributed to an increased mechanical strength of the concrete and a positive morphological modification of its surface by densifying and sealing surface pores. These results support the potential of diatoms as an effective solution to improve the properties and durability of recycled concrete.
Increased water conductivity levels have been proposed as a key factor to explain the occurrence ... more Increased water conductivity levels have been proposed as a key factor to explain the occurrence of teratological forms in freshwater diatom assemblages. The current study aimed to carry out an experiment on a laboratory scale to assess the response of periphytic diatoms to artificially increased salinity levels. The obtained results show that: a) the proportion of aberrant cells increased in high conductivity treatments, b) developed teratologies were preserved in diatom populations even after being translocated to normal conditions, and c) the degree of valve outline deformation in the dominant species was proportional to the induced water conductivity. All these data support previous field observations that linked high electrolyte content and the abundance of aberrant cells among microalgal communities in continental aquatic ecosystems.
Nitrous oxide (N2O) emissions in High Rate Algal Ponds (HRAP) can negatively affect the sustainab... more Nitrous oxide (N2O) emissions in High Rate Algal Ponds (HRAP) can negatively affect the sustainability of algal-bacterial processes. N2O emissions from a pilot HRAP devoted to biogas upgrading and digestate treatment were herein monitored for 73 days. The influence of the pH (7.5, 8.5, and 9.5), nitrogen sources (100 mg L−1 of N–NO2-, N–NO3-, and N–NH4+) and illumination on N2O emissions from the algal-bacterial biomass of the HRAP was also assessed in batch tests. Significantly higher N2O gas concentrations of 311.8 ± 101.1 ppmv were recorded in the dark compared to the illuminated period (236.9 ± 82.6 ppmv) in the HRAP. The batch tests revealed that the highest N2O emission rates (49.4 mmol g−1 TSS·h−1) occurred at pH 8.5 in the presence of 100 mg N–NO2-/L under dark conditions. This study revealed significant N2O emissions in HRAPs during darkness.
The objective of this study was to explore the environmental factors having the greatest influenc... more The objective of this study was to explore the environmental factors having the greatest influence on the distribution and abundance of epipelic diatom species in different wetlands in southern Spain. We previously defined four groups of conductivity categories: fresh (< 0.8 mS cm−1), oligosaline (< 8 mS cm−1), mesosaline (8–30 mS cm−1) and eusaline (> 30 mS cm−1). A dbRDA analysis performed on a subset of 36 of the 53 wetlands, using a total of 25 environmental variables, showed that five environmental variables (conductivity, pH, wetland area, silicates, and total suspended solids) were the best explanatory variables for the diatom assemblage, with conductivity being the main explanatory variable. Nonmetric multidimensional scaling (nMDS) analysis performed on the set of 53 wetlands revealed significant differences in diatom composition among the four conductivity groups. The key species in the eusaline group were Tryblionella pararostrata, Halamphora sp.1 and Cocconeis euglypta, whereas in the mesosaline and oligosaline group, these were Navicula veneta, Tryblionella hungarica and Nitzschia inconspicua. Finally, in the fresh group dominated Achnanthidium minutissimum, Navicula veneta and Gomphonema exilissimum. This study on epipelic diatoms can therefore contribute to the knowledge of these organisms in a European region with a high diversity of wetland typologies.
The initial valves of two Cymbella species are observed under a scanning electron microscope, and... more The initial valves of two Cymbella species are observed under a scanning electron microscope, and the perizonium ultrastructure of Cymbella is revealed for the first time. The perizonium is composed of alternate nodes and internodes and lacks transverse perizonium bands. Four new species, Cymbella apiculatophora sp. nov., C. hunanensis sp. nov., C. juglandis sp. nov. and C. menyuanensis sp. nov., are described using light and scanning electron microscopy based on epilithon samples collected from rivers in Hunan and Qinghai Provinces, China. Cymbella menyuanensis is a typical Cymbella species that closely resembles species in the group around C. cymbiformis Agardh, the type species of the genus. Cymbella apiculatophora is similar to C. sinensis Metzeltin & Krammer, while Cymbella hunanensis is closer to the C. hustedtii Krasske group. The last species, C. juglandis, has a cymbelloid valve outline, an obscured intermissio, internal occlusions of the areolae, dorsally deflected distal raphe fissures and a divided apical pore field at each apex, and it does not appear to belong to any group. In addition, new observations on C. cf. excisiformis Krammer and C. hustedtii are reported. The current concept of the genus Cymbella does not represent a monophyletic group as shown by molecular phylogenetic analyses. However, these analyses are still at the preliminary stage and are not yet sufficient to support a complete revision of the genus. Thus, although extremely diverse ultrastructural features are observed in the six Cymbella species investigated in this paper, we prefer to keep them within Cymbella at this moment for the sake of nomenclatural stability.
Aim Understanding the roles of deterministic and stochastic processes in community assembly is es... 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.
Interspecific abundance-occupancy relationships (AOR) have been addressed as one of the most impo... more Interspecific abundance-occupancy relationships (AOR) have been addressed as one of the most important questions regarding the spatial ecology of diatoms. Whereas positive interspecific AOR is a common feature of ecological communi- ties, little is known about its causes and consequences. Studies to date confirm that AOR depends mostly on the ecological features exhibited by the species pool ana- lyzed, particularly niche characteristics and habitat guilds. The present study aims to test the persistence of such patterns using pond diatoms at a mesoscale level. Epiphytic and planktonic diatoms were collected in 29 shallow ponds throughout the Northern Iberian Plateau. Analysis of covariance (ANCOVA) tests revealed contrasting patterns when both assemblages are compared; for a given abundance level, epiphytic species were present in twice as many locations as planktonic ones, with noticeable effects also attributable to cell biovolume and motile guild. Contrary to our expectations, niche characteristics, measured in terms of species sensitivity and indicator value with respect to abiotic variables, had a negligible effect on AOR models. The consequences of such results are briefly discussed at a theoretical level.
Aim To evaluate the patterns of stream diatom beta diversity in islands versus continents across ... more Aim To evaluate the patterns of stream diatom beta diversity in islands versus continents across scales, to relate community similarities with spatial and environmental distances and to investigate the role of island characteristics in shaping insular diatom beta diversity. Location Africa, America, Europe and the Pacific. Time Period Present. Major Taxa Studied Stream diatoms. Methods We compared diatom beta diversity between islands and continents at large scales (within biogeographic regions) in two study regions (America and Europe) and at small scales (within islands/equivalent areas in continents) in three regions (Africa, America and Europe) partitioning beta diversity into turnover and nestedness components. We used a partial Mantel test and distance–decay curves to assess how diatom beta diversity on islands and continents is affected by spatial and environmental distances. Finally, using island data from all four regions, we evaluated the relationship between island beta diversity and island latitude, area, age and isolation using linear models. Results At large scales, mean dissimilarities were higher on islands than in continents in Europe but lower in America. At smaller scales, the differences varied mostly depending on island isolation. Beta diversity was mainly caused by species turnover. Partial Mantel test and distance–decay curves revealed that spatial and environmental distances shaped diatom beta diversity at large, but not at small scales. Moreover, diatom beta diversity on islands was affected by island latitude, age and isolation, but not by island area. Main Conclusions Diatom beta diversity on islands versus continents and its responses to spatial and environmental factors are scale and region dependent. Incomplete colonisation, evolutionary processes and environmental filtering likely contribute to insular beta diversity, which further varies with island latitude, age and isolation. This study sheds new light on beta diversity of microorganisms on islands and suggests that beta diversity should be explicitly considered in island biogeographical research.
This research presents a significant contribution to the methodologies and protocols for studying... more This research presents a significant contribution to the methodologies and protocols for studying diatom communities in cryoconite holes on glaciers. Cryoconite holes are unique microenvironments found on glacial surfaces that support intricate microbial ecosystems, with diatoms playing a pivotal role in these communities. The refined methodologies developed in this study include optimizing sampling techniques to ensure that collections are both representative and diverse, which is crucial for accurate ecological assessments. Additionally, advanced digestion processes have been implemented to effectively isolate and purify diatom samples while minimizing contaminants, thereby improving sample integrity. Improved microscopic mounting techniques enhance visual clarity, facilitating more precise identifications of diatoms under the microscope. Furthermore, integrating DNA-based taxonomy broadens the taxonomic scope, providing valuable molecular insights into the diversity and evolutionary relationships of diatoms. Collectively, these protocols aim to enhance the reliability, depth, and multidimensional understanding of diatom ecology in cryoconite holes and broader glacial ecosystems, ultimately contributing to the field of glaciology and microbial ecology.
The use of diatoms as ecological indicators of water quality is well established globally, with n... more The use of diatoms as ecological indicators of water quality is well established globally, with numerous studies supporting the effectiveness of diatom-based biotic indices for monitoring the ecological status of freshwaters. These metrics typically rely on the relative abundance of “indicator taxa,” their overall sensitivity to impairment, and their environmental optimum along a pollution gradient. In South America, microalgal assemblages have only recently been used to monitor and evaluate the water quality in continental waters. This study aims to design and validate a new diatom metric, the Ecuador Diatom Index (EDI), to enhance water quality assessment in Ecuadorian river basins. The EDI reflects the overall limnological condition of a river, measured through various abiotic parameters integrated into the water quality index. Biological sampling was conducted at 111 stations across the Ecuadorian river basins. Notable differences were observed in floristics and autoecological parameters compared to other diatom-based methods. Statistical analyses revealed that beyond optimum and tolerance, incorporating specific frequency of occurrence and goodness-of-fit to a Gaussian response curve improves the reliability of this metric, surpassing the results of the commonly used specific pollution sensitivity index.
Cuatro Cienegas is a natural geopark that exhibits a vast reservoir of geological, geochemical an... more Cuatro Cienegas is a natural geopark that exhibits a vast reservoir of geological, geochemical and geobiological diversity, including shallow-water microbial carbonates with clotted micrite textures known as thrombolites. Thrombolites mainly occur as domes and massive irregular carbonates along the margins of Rio Mezquites in Cuatro Cienegas, northern Mexico. Because their clotted textures result from diverse abiotic and biotic interactions at the microbial–mineral interface, the formation of clots in thrombolites continues to be a contentious issue. Through a petrographic, scanning electron microscopy and bulk biogeochemical analysis, this study investigated the role of endolithic cyanobacteria in the generation of thrombolitic clots. Their microclotted fabric is characterized by 50 to 200 μm peloidal clots, pores, fenestrae, crevices and cavities as main components. Thrombolites also contain microbial microstructures, some of them interpreted as the endolithic contribution to the genesis of clotted micrite. Thrombolites and associated fresh microbial mats are composed of cyanobacteria, green algae and diatoms. Petrography and cast-embedded scanning electron microscopy micrographs also show the presence of filamentous endolithic cyanobacteria inside the thrombolitic framestone. The geochemical bulk characterization for carbon and oxygen isotopes shows average values of −0.7‰ Vienna PeeDee Belemnite and −8.0‰ Vienna PeeDee Belemnite, respectively. The organic matter preserved in their mineral matrix and associated microbial mats indicated the putative presence of cyanobacterial hopanoids. The high diversity of peloids and the microboring evidence, together with observed microstructures, suggest that clots may also form by the concurrent precipitation and dissolution of the thrombolites. Among the known sources of peloidal clots, microbial boring may be an additional micrite source for clot formation. Microbial carbonate dissolution may also promote heterogenous lithification by hydration and dehydration cycles. Thrombolites reflect complex systems due to concurrent interactions among producers (phototrophs), consumers (small invertebrates), mineralization (carbonate precipitation induced by phototrophs) and endolithic dissolution. The microstructures inside thrombolites, in conjunction with biogeochemical attributes of bulk thrombolites, may provide unambiguous sedimentary biosignatures.
Anales Del Jardin Botanico De Madrid, 2019
Resumen. Se describe la diatomea Encyonema nevadense S.Blanco & al. sp. nov. como especie nueva, ... more Resumen. Se describe la diatomea Encyonema nevadense S.Blanco & al. sp. nov. como especie nueva, a partir de muestras de epiliton recogidas en una laguna de alta montaña del Parque Nacional de Sierra Nevada. Este taxon se caracteriza por la presencia de valvas lanceoladas estrechas con una moderada dorsiventralidad, y la presencia de areolas con aperturas externas irregulares. Se compara la población tipo con la de Encyonema perpusillum (A.Cleve) D.G.Mann y sus variedades, la especie morfológicamente más cercana dentro del género. Se discuten brevemente las impliaciones ecológicas y biogeográficas del descubrimiento.
Construction and Building Materials
Nova Hedwigia, Jan 3, 2018
As an effective way of poverty alleviation, the poverty alleviation through industry plays an imp... more As an effective way of poverty alleviation, the poverty alleviation through industry plays an important role in China's poverty alleviation and development career. After years of poverty alleviation and development, the industry poverty alleviation in Wuling Mountains has obtained certain achievements, but it still has some problems, such as unreasonable industrial structure, the limit of poverty alleviation's leading ability and so on. Based on the case study of the Wuling Mountains, this paper analyzes present situation and reasons of the industry poverty alleviation of the region, and puts forward some suggestions for poverty alleviation, such as strengthening regional government coordination, making the special advantage industries bigger and stronger, establishing demonstration zone of industry poverty alleviation, fostering leading enterprises vigorously and so on, which can provide decision support for the government at all levels to innovate the model of poverty alleviation and win the battle for the poverty alleviation in the new period.
Background and objective: Training a deep convolutional neural network (CNN) for automatic image ... 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.
Guía de las especies Exóticas e Invasoras de los Ríos, Lagos y Estuarios de la Península Ibérica., 2020
Handbook of Algal Science, Technology and Medicine, 2020
Cyanobacteria, an abundant source of natural products as biomedical compounds have emerged as a n... 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.
Handbook of Algal Science, Technology and Medicine, 2020
Today, agro-industry is a key economic sector worldwide with a large associated generation of was... 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.
Modern Trends in Diatom Identification: Fundamentals and Applications, 2020
Correct identification of diatom taxa is indispensable for diatom-based water quality studies, as... 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.
Modern Trends in Diatom Identification: Fundamentals and Applications, 2020
This chapter introduces the antecedents, motivation, and necessity of the use of automatic identi... 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.
Modern Trends in Diatom Identification: Fundamentals and Applications, 2020
Diatom identification must consider the large variability in both morphological and morphometric ... 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.
Modern Trends in Diatom Identification: Fundamentals and Applications, 2020
Diatom metrics methods are becoming important tools for the assessment of environmental condition... 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.