Phycology diatoms algae Research Papers (original) (raw)

From field-collected samples, two Icelandic diatom species were studied under light and electron microscopy, resulting in a newly described species and an emended description with a nomenclatural status change. A discussion on the morphological features of these taxa and their taxonomic affinities with related species is presented. Nitzschia imae is described from Blue Lagoon, south-west Iceland. The main diagnostic criteria include the presence of two differences morphotypes, one with obtusely rounded apices and the other with slightly asymmetrical valve outline and broadly rounded apices. Additionally, we propose an emended description for Hannaea arcus var. linearis since there is no concordance between morphometric features in the protologue and the type illustration.

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- Diatom taxonomy, Diatoms, Phycology diatoms algae, New Species

The Upper Paraná River floodplain is one of the few remaining non-dammed stretches in Brazil. It has a typical fluvial dynamics represented by the flood pulse and a highly complex habitat, which allows the existence and maintenance of a great biodiversity, including diatom species. As it happens in tropical lowland environments, also in this floodplain, the genus Eunotia is one of the most diverse and abundant diatom groups. Therefore, this study addresses morphologic and morphometric details of a new species and the most abundant Eunotia species in sediment cores from two wetland lakes. The morphological characteristics from each species were obtained through microscopy documentation of cell walls, and compared with other related species.

- by Saúl Blanco
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- Diatom taxonomy, Diatoms, Phycology diatoms algae, Diatom

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.

- by Saúl Blanco
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- Phycology, Bioindicators, Stream ecology, Taxonomy

The Island of Majorca (Spain) is characterized by a Mediterranean climate and a karstic geology that favors
the formation of numerous springs and spring–fed streams on the island’s Northwester zone. Water and epilithic diatom
samples were collected from two springs and four spring–fed streams, located at altitudes ranging from 0 to 756 m a.s.l.,
in different seasons between 2005 and 2008. Water chemistry in these systems is characterized by high concentrations of
dissolved calcium and pH values ranging from 6.6 to 8.4. A total of 111 diatom taxa belonging to 40 genera were found and
the most abundant taxa were illustrated with LM and SEM. The diatom communities of the studied sites were dominated by
species such as Achnanthidium minutissimum, A. pyrenaicum, Amphora pediculus, Cymbella vulgata, Diploneis separanda,
Encyonopsis minuta, Gomphonema lateripunctatum and Navicula cryptotenella, reflecting the calcareous geological nature
of Majorca Island. In the framework of the study 22 diatom taxa, which are new for Balearic Islands were recorded, such
as Achnanthidium straubianum, Amphora indistincta, Cymbella lange–bertalotii,Encyonopsis subminuta, Karayevia kolbei,
Navicula aff.margalithii, N. reichardtiana and N. subalpina. In addition, a new freshwater diatom species belonging to the
genus Cymbopleura,C. margalefii was found in the Torrente of Deià. Cymbopleura margalefiiis described as a new species
based on LM and SEM observations, and compared with similar taxa. A checklist of the 309 diatom taxa recorded so far from
the Balearic Islands is also presented.

- by Saúl Blanco and +1
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- Phycology, Stream ecology, Taxonomy, Algae

The diatom Didymosphenia geminata (Lyngbye) M.Schmidt has been commonly considered a taxon restricted to pristine habitats in mountainous areas of circumboreal regions. Recent studies show that it has a broader distribution and ecological amplitude. This shift seems to have occurred recently, as it now forms large growths in rivers within its native geographical area (North America, Europe) but also mass developments have recently appeared in New Zealand, where it is considered an aggressive invasive species with dramatic ecological and economic impacts. This nuisance organism grows attached in streambeds and may impact freshwater fish and aquatic plants and insects, causing severe disturbance in food webs. This paper investigates the historic and current biogeographic range of this invasive species (and varieties) based on 1000 citations collected mainly from the scientific literature. The locations where this diatom has appeared, including both fossil and recent records, are presented in world distribution maps. Our results confirm that the native range of D. geminata is almost restricted to the Holarctic region, though its distribution area is broader than usually reported in the literature. The ecological profile of this alga, along with its nuisance effects, is also discussed. Excessive growths do not only appear in areas where this species is presumably exotic. Contrarily to general statement, reports of mass developments of D. geminata date back to the 19th century. World references to D. geminata have increased exponentially during the last decades; however; with respect to the whole diatom literature during the XIX and XX centuries, the relative frequency of citations has decreased progressively.

- by Saúl Blanco
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- Phycology, Stream ecology, Taxonomy, Invasive species ecology

El presente trabajo supone una contribución al conocimiento de las diatomeas dulceacuícolas españolas. Se describe la diatomea Eunotia emmae sp. nov. a partir de muestras de algas epífitas recogidas en una laguna somera oligo-mesotrófica de la provincia de León. La muestra fue tomada y procesada siguiendo los protocolos comunes para diatomeas lacustres. Las características morfológicas y ultraestructurales de este nuevo taxón se detallan e ilustran mediante imágenes de microscopía óptica y electrónica. La diagnosis diferencial con otras especies afines muestra que la combinación de caracteres de E. emmae (principalmente la forma biconvexa de la valva y un conspicuo sternum) es única. Abstract This work aims at contributing to the knowledge of Spanish freshwater diatoms. The diatom Eunotia emmae sp. nov. is described from samples of epiphytic algae collected in a shallow, oligo-mesotrophic lake from the province of Leon (Spain). The sample was taken and processed following the usual protocols for lacustrine diatoms. Morphological and ultrastructural features of this new taxon are detailed and illustrated by means of light and scanning electron microscopy images. Differential diagnosis against related species shows that the combination of features in E. emmae (mainly the presence of biconvex valves and a conspicuous sternum) is unique.

- by Saúl Blanco
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- Diatom taxonomy, Diatoms, Phycology diatoms algae, Diatom Ecology

A factorial experiment was carried out in order to assess the effects of four treatment steps in diatom processing techniques (the quantity of hydrogen peroxide added to the sample, the time allowed to the digestion reaction, the use of centrifugation and the method used to settle the frustules onto the coverslip) on different aspects of the quality of the resulting microscopic slide: the concentration of organic and inorganic matter, the density, randomness and homogeneity of the frustule distribution in the slide, and the abundance of broken frustules and girdle views. The results show no significant effects of any of the experimental treatments on the proportion of broken frustules in the samples. No significant effects were related to the duration of the oxidation reaction in any of the aspects evaluated in the quality of the slides. A sample:hydrogen peroxide ratio of 1:1 for a 6-h oxidizing reaction can be used to optimize the protocol. Despite being more time consuming, the use of successive decantations instead of centrifuging is more appropriate to achieve better results. Slide quality can also be improved by leaving the coverslips to dry at room temperature in order to improve the distribution of frustules.

- by Saúl Blanco
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- Phycology, Stream ecology, Taxonomy, Algae

The Water Framework Directive (WFD) requires that the European Union countries determine the biological state of their waters with respect to sites of high quality. Despite bioindicators have been widely applied in running waters and deep lakes throughout all Europe, little is known about their applicability in shallow lakes. In this context, the objective of this work is to check the effectiveness of epiphytic diatoms as indicators of the trophic state in six shallow lakes of León Province (NW Spain). Epiphyton was sampled from helophyte stems in six shallow lakes covering different ecological conditions. A significant correlation was found between the total nitrogen concentration and the diatom indices SPI (Specific Polluosensitivity Index) and BDI (Biological Diatom Index), this correlation being lower with respect to the total phosphorus concentration. The classification of the lakes according to the trophic and saprobic levels based on diatoms corresponds to that obtained from the analysis of the limnological and chemical parameters of the studied systems. Despite the use of these indices has been traditionally limited to rivers and channels, our results show the effectiveness of epiphytic diatoms as biological indicators of the quality of water in Mediterranean shallow lakes and the applicability of common diatom indices for biomonitoring purposes in these aquatic ecosystems.

- by Saúl Blanco
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- Phycology, Limnology, Bioindicators, Stream ecology

Doñana temporary ponds (southwest Spain) form a system of water bodies of remarkable ecological singularity with a high protection status. However, its species composition, diversity, and distribution of algal communities are largely unknown. During a biological survey carried out in shallow temporary ponds in 2010, several unknown diatom taxa were found in various population densities in the epiphyton of these systems. Detailed light and scanning electron microscopy observations allowed the description of five of them (Eunotia vozmedianoi, Planothidium lacustre, Halamphora tharsis, G. undulans and Pinnularia acidophila var. baetica) as taxa new to science. Differential diagnostic criteria with respect to similar taxa, together with ecological and biogeographical implications of these findings, are briefly discussed. Our results support recent studies indicating that endemism in diatoms might be a widespread pattern.

- by Saúl Blanco and +1
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- Phycology, Stream ecology, Taxonomy, Algae

In 2000 the European Parliament and The European Union Council recommended that member countries assess water quality using diatoms, as part of the phytobenthos. In Italy this recommendation has given new impetus to the study of diatom communities and the application of biotic indices. During the summer of 2004, a total of 11 rivers of the Trentino province (Northern Italy) were sampled, revealing the presence in low abundances of the diatom Didymosphenia geminata (Lyngbye) M. Schmidt. The sites where this diatom occurred were characterised by a low pollution impact; they were also lake fed or had a regulated flow regime, although with different geologies. Morphological features of D. geminata frustules were analysed using LM and SEM and specimens could be referred to the morphotype "geminata". In many countries this species is expanding its distribution and in New Zealand it is considered an invasive alga. This work provides an initial report on the presence of D. geminata in the Trento province, and contributes to increasing the knowledge on its distribution in Italy and its ecology in the Alps.

- by Saúl Blanco
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- Phycology, Stream ecology, Taxonomy, Invasive species ecology

: A water quality index (WQI) developed by the Canadian council of ministers of the Environment
(CCME) was applied to chikkakere , a lake at Periyapatna, Mysore district , Karnataka state, India to study its impact
on the protection of aquatic life. The index in the lake is rated as poor. The water quality is almost endangered or
deteriorated and the conditions often deviate from natural levels, Microcystis aeruginosa blooms are dominant in the
lake. These permanent blooms often cause huge fish kills. Nitchzia species are also dominant among
Bacillariophyaceae indicating pollution. Overall the lake water is unable to protect aquatic life. The water quality failed
to satisfy the parameters and its use for purposes like Drinking, Aquatic, Recreation, irrigation and livestock.

"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."

- by Saúl Blanco and +1
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- Phycology, Bioindicators, Stream ecology, Taxonomy

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).

- by Saúl Blanco
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- Phycology, Bioindicators, Stream ecology, Taxonomy

A population of an unknown Psammothidium species (Bacillariophyta, Achnanthidiaceae) was found in core sediments collected from Cimera Lake, an oligotrophic, undisturbed mountain lake in Central Spain (Gredos mountain range). The morphology and ultrastructure of this taxon is hereby documented in detail by means of light (LM) and scanning electron (SEM) micrographs. Morphologically, the closest taxon is P. levanderi, and the type of this species is analyzed here to provide a differential diagnosis. A comparison with other similar small Psammothidium species with an elliptic outline show that the combination of features exhibited by this taxon is unique and it is thus described here as Psammothidium toroi sp. nov.

- by Saúl Blanco
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- Diatom taxonomy, Diatoms, Phycology diatoms algae, Benthic Diatoms

The terrestrial diatom Microcostatus schoemanii sp. nov. is described from dry soils of the Faan Meintjies Nature Reserve (North-West Province, South Africa). Microcostatus cholnokyi sp. nov. and Microcostatus angloensis sp. nov. are described from sandy soils at a colliery near the town of Kriel (Mpumalanga Province, South Africa). The morphology of these taxa is examined using both light (LM) and scanning electron microscopy (SEM) and new taxa are compared with similar species. In M. schoemanii the density of the striae combined with the valve outline and the distance between the central raphe endings are the main distinguishing morphological features. M. cholnokyi is differentiated by the presence of a conopeum and the distinct structure of the microcostae. M. angloensis is similar to M. schoemanii but differentiated by the shape of the cell and the apices, the angle of striation and the distance in between the proximal raphe endings.

- by Jonathan Taylor and +2
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- Phycology, Stream ecology, Taxonomy, Algae

Biotic indices based on macro-invertebrates and diatoms are frequently used to diagnose ecological quality in watercourses, but few published works have assessed their effectiveness as biomonitors of the concentration of micropollutants. A biological survey performed at 188 sites in the basin of the River Duero in north-western Spain. Nineteen diatom and six macro-invertebrate indices were calculated and compared with the concentrations of 37 different toxicants by means of a correlation analysis. Several chemical variables analysed correlated significantly with at least one biotic index. Sladecˇek’s diatom index and the number of macro-invertebrate families exhibited particularly high correlation coefficients. Methods based on macro-invertebrates performed better in detecting biocides, while diatom indices showed stronger correlations with potentially toxic elements such as heavy metals. All biotic indices, and particularly diatom indices, were especially sensitive to the concentration of fats and oils and trichloroethene.

- by Saúl Blanco
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- Phycology, Water quality, Bioindicators, Stream ecology

Several methods for water quality assessment have been proposed for European rivers. The EU Water Framework Directive requires the use of ecological indicators for stream monitoring networks and has encouraged research on biological indices. However, there is a lack of integrative studies comparing the efficiency of such methods in the determination of the ecological status in rivers. The present work, carried out in the Spanish side of the Duero Basin, the largest in the Iberian Peninsula, aimed at comparing different water quality indices. The survey was conducted during autumn 2003 and summer 2004 in 95 sites covering the entire basin. Epilithic diatoms and benthic macroinvertebrates were sampled and analysed following standard methods for the calculation of the macroinvertebrate index IBMWP and 18 different diatom indices. Additionally, water physical and chemical variables were measured and Habitat (IHF) and Riparian (RQI) indices were determined in situ. In general, both diatom and macroinvertebrate indices were strongly correlated with each other and with abiotic factors. The highest correlation coefficients between water physical and chemical data (especially with the concentrations of phosphates and N-derived compounds) were obtained for the diatom index SPI and the IBMWP, though no biotic method detected changes in the concentrations of toxicants (Zn2+, Cr III). The use of diversity metrics as monitoring indices is not recommended. The results indicated that several different biotic indices, based on a wide range of biotic communities, must be integrated in water quality surveillance protocols, in order to reflect complementary aspects of the ecological status in river ecosystems.

- by Saúl Blanco
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- Phycology, Water quality, Bioindicators, Stream ecology

En verano de 2005 se realizó un muestreo en 140 estaciones de la red ICA de la cuenca del Duero, a fin de determinar la calidad ecológica del agua en estos puntos utilizando diatomeas como bioindicadores. Los resultados muestran que el índice de diatomeas más apropiado para esta cuenca es el Índice de Poluosensibilidad Específica(IPS). Según este índice, el 61, 4% de los puntos alcanzan un estado ecológico de sus aguas "Bueno" o "Muy Bueno", cumpliendo con los objetivos determinados por la Directiva Marco del Agua. Sin embargo, el 38, 6% de los puntos no llegan a un nivel aceptable según dicho criterio.

- by Saúl Blanco
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- Phycology, Water quality, Bioindicators, Stream ecology

Se propone un método para la toma de muestras de diatomeas epífitas en lagos y lagunas con el fin de aplicar dichas comunidades algales en la determinación del estado ecológico de estos sistemas acuáticos de acuerdo con los requisitos de la Directiva Marco del Agua. La metodología se basa en el empleo de muestradores tipo Kornijów para la recolección del epifiton desarrollado sobre helófitos. Los resultados preliminares muestran la eficacia de este método en la evaluación de la calidad del agua. La aplicación de esta sencilla metodología permite el empleo de las diatomeas epífitas como indicadores biológicos de los medio lacustres, generando resultados reproducibles en el tiempo y basados en un protocolo común fácilmente aplicable.

- by Saúl Blanco
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- Phycology, Limnology, Bioindicators, Stream ecology

Metal pollution of aquatic habitats is a major and persistent environmental problem. Acid mine drainage (AMD) affects lotic systems in numerous and interactive ways. In the present work, a mining area (Roșia Montană) was chosen as study site, and we focused on two aims: (i) to find the set of environmental predictors leading to the appearance of the abnormal diatom individuals in the study area and (ii) to assess the relationship between the degree of valve outline deformation and AMD-derived pollution. In this context, morphological differences between populations of Achnanthidium minutissimum and A. macrocephalum, including normal and abnormal individuals, were evidenced by means of valve shape analysis. Geometric morphometry managed to capture and discriminate normal and abnormal individuals. Multivariate analyses (NMDS, PLS) separated the four populations of the two species mentioned and revealed the main physico-chemical parameters that influenced valve deformation in this context, namely conductivity, Zn, and Cu. ANOSIM test evidenced the presence of statistically significant differences between normal and abnormal individuals within both chosen Achnanthidium taxa. In order to determine the relative contribution of each of the measured physico-chemical parameters in the observed valve outline deformations, a PLS was conducted, confirming the results of the NMDS. The presence of deformed individuals in the study area can be attributed to the fact that the diatom communities were strongly affected by AMD released from old mining works and waste rock deposits.

- by Saúl Blanco and +1
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- Geometric Morphometrics, Acid Mine Drainage, Diatoms as indicators, Diatoms

As component of an exhaustive investigation on the ecological studies of diatom communities of River Dilimi in Jos, the spatio-temporal variation of four different diatom communities was investigated. As a derivative of these studies, a comprehensive compilation was made of the diatom flora of the upper mainstream channel of the river. Two hundred and nine (198 pennate and 11 centric) diatom species belonging to twenty five families and forty genera were recorded. The genera most represented belong to Pinnularia (26 taxa), Gomphonema (26 taxa), Cymbella (21 taxa), Navicula (19 taxa) and Eunotia (14 taxa). Gomphonema parvulum (Kutz.) Grunow, Nitzschia palea (Kütz.) Smith, Navicula arvensis and Cymbella minuta Bleisch ex Rabh Husted were the most noticeable diatoms with respect to both frequency of occurrence and relative abundance across samples.

A new benthic diatom species, Gomphonema vidalii sp. nov., is described with light (LM) and scanning electron microscopy (SEM) observations. It was found in three Mediterranean watercourses: Farfa stream (Central Italy), Bévéra and Paillon streams (South-Eastern France). Valves have a clavate shape and striae are slightly radial, the central ones being shorter than the others. One stigma and two to four stigmoid areolae are present in the central area. Only the central stigma is easily resolvable with LM. SEM analyses revealed that striae have double rows of bean-shaped areolae. The central stigma opens in the internal side of the valve as a slit in the central nodule, while the stigmoid areolae located around the central area are only externally visible. In connective view, an uninterrupted line of puncta is present on the valve mantle. G. vidalii belongs to the group of Gomphonema species with doubly-punctate striae, feature which was considered by some authors typical of the genus Gomphoneis. Peculiar of Gomphonema vidalii is also the presence of an isolated punctum in the central area, different in structure from stigmata and stigmoids which can be found in some Gomphonema and Gomphoneis species.

- by Saúl Blanco
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- Phycology, Stream ecology, Taxonomy, Algae

A new Planothidium species, Planothidium galaicum sp. nov. is described on the basis of light and electron microscopy
investigations of its frustule morphology. This diatom was found in the epiphyton of Himanthalia elongata at Muxía
coast (Galicia, northwest Spain). A discussion of the morphological features of this taxon and their taxonomic affinities
with related species, is presented

- by Saúl Blanco
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- Diatom taxonomy, Diatoms as indicators, Diatoms, Phycology diatoms algae

"This work aims to analyse the response of epilithic diatom communities to environmental gradients in subtropical temperate
southern Brazilian rivers to contribute to the development of a widely applicable methodology for water-quality monitoring.
Samples for physical, chemical and biological determination were collected monthly, from December 2001 to November
2002 and from March 2003 to February 2004, at 9 stations along the rivers Pardo and Pardinho in the hydrographical basin
of Rio Pardo, State of Rio Grande do Sul (RS), Brazil. Physical and chemical variables (water temperature, pH, dissolved
oxygen, biochemical oxygen demand, chemical oxygen demand, nitrates, nitrites, phosphates and total dissolved solids) and
biological variables (epilithic diatom communities) were used as parameters for water-quality assessment. The data matrix
was examined by means of a multivariate ordination using Detrended Correspondence Analysis (DCA). In total, 270 taxa
were identied to specic or infra-specic levels. The results showed that of all the physical and chemical variables used, the
main gradient along the DCA rst axis was eutrophication, which was indicated by its signicant correlation with phosphates
( p < 0.001). Hence, the species’ scores on the DCA axis were used as an operational criterion for indicating their tolerance to
eutrophication. From this analysis, the 10 taxa that were the most tolerant to eutrophication were: Cyclotella meneghiniana,
Fallacia monoculata, Nitzschia acicularis, N. clausii, N. nana, N. palea, Nitzschia sp., Pinnularia sp., Sellaphora pupula
sensu lato and Ulnaria acus. The present study showed that epilithic diatom assemblages reect anthropogenic changes in
hydrographic basins in subtropical temperate streams, especially pollution by organic enrichment and eutrophication."

- by K. Katoh and +1
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- Phycology, Bioindicators, Stream ecology, Taxonomy

During a biological survey carried out in 2009, epiphytic and phytoplanktonic diatom assemblages of three shallow saline lakes in the South of the Bolivian Altiplano (Lipez Area) (>4100 m asl), were studied. Within the identified taxa, Navicula pseudogracilis, Staurophora vilamae, Halamphora atacamana, Halamphora carvajaliana, Halamphora atacamae, Denticula valida f. major and Surirella chilensis were studied in detail. For each of these, a brief morphologic and morphometric description, a collection of bibliographic references where the taxon is cited or illustrated in the scientific literature, and light and scanning electronic microscopy images are presented. S. vilamae and D. valida f. major are cited for the first time out of their type localities, this last taxa observed for the first time in the world since 1894. Besides, N. pseudogracilis is cited as a new species for Bolivia and the ultrastructure of this taxon and D. valida f. major were illustrated for the first time.

- by Saúl Blanco and +1
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- Phycology, Stream ecology, Taxonomy, Bolivia

Diatom indices developed in certain geographic regions are frequently used elsewhere, despite the strong evidence that such metrics are less useful when applied in regions other than that where species–environment relationships were originally assessed, showing that species have particular autoecological requirements in different geographic areas. The goal of this study was to develop a new metric, the Duero Diatom Index (DDI), aimed at monitoring water quality in Duero basin watercourses (NW Spain). In summer 2008 and 2009, a total of 355 epilithic diatom samples were collected following standard protocols. The 2008 samples were used to develop the DDI, whereas the samples collected during 2009 were used in the index testing. Weighted averages method was used to derive the autoecological profiles of diatoms with respect to pH, conductivity, biological oxygen demand, ammonia, nitrates, and phosphates. The optimum and tolerance values for the measured environmental variables were determined for 137 taxa with abundances and frequencies of occurrence above 1 %, and subsequent trophic indicator and sensitivity values were defined for the DDI. The correlation between the observed and the diatom-inferred nutrient concentrations was highest for phosphates (ρ S = 0.72). Significant statistical relationship were observed between DDI values and the chemistry-based General Quality Index values (p = 0.006) and the specific pollution index (SPI) diatom metric (p = 0.04). DDI has demonstrated a better correlation with water chemistry than SPI diatom metric.

- by Saúl Blanco
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- Phycology, Stream ecology, Taxonomy, Algae

The present paper deals with the eco-taxonomic observations on Epithemia adnata (Kützing) Brébisson collected from Murguma reservoir of Purulia district in West Bengal, India. For this purpose Differential interference contrast (DIC) and phase contrast images were taken covering whole size range of the valves and FE SEM also done. Ecological parameters were also considered. Authors tried to compare these taxa with the other six taxa of “adnata” group available from scientific literature.

- by Jai Prakash Keshri and +1
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- Phycology diatoms algae

Flux of siliceous plankton and taxonomic composition of diatom and silicoflagellate assemblages were determined from sediment trap samples collected in coastal upwelling-influenced waters off northern Chile (30°S, CH site) under ‘‘normal’’ or non-El Nino (1993–94) and El Nino conditions (1997–98). In addition, concentration of biogenic opal and siliceous plankton, and diatom and silicoflagellate assemblages preserved in surface sediments are provided for a wide area between 27° and 43°S off Chile. Regardless of the year, winter upwelling determines the maximum production pattern of siliceous microorganisms, with diatoms numerically dominating the biogenic opal flux. During the El Nino year the export is markedly lower: on an annual basis, total mass flux diminished by 60%, and diatom and silicoflagellate export by 75%. Major components of the diatom flora maintain much of their regular seasonal cycle of flux maxima and minima during both sampling periods. Neritic resting spores (RS) of Chaetoceros dominate the diatom flux, mirroring the influence of coastal-upwelled waters at the CH trap site. Occurrence of pelagic diatoms species Fragilariopsis doliolus, members of the Rhizosoleniaceae, Azpeitia spp. and Nitzschia interruptestriata, secondary components of the assemblage, reflects the intermingling of warmer waters of the Subtropical Gyre. Dictyocha messanensis dominates the silicoflagellate association almost year-around, but Distephanus pulchra delivers ca. 60% of its annual production in less than three weeks during the winter peak. The siliceous thanatocoenosis is largely dominated by diatoms, whose assemblage shows significant qualitative and quantitative variations from north to south. Between 27° and 35°S, the dominance of RS Chaetoceros, Thalassionema nitzschioides var. nitzschioides and Skeletonema costatum reflects strong export production associated with occurrence of coastal upwelling. Both highest biogenic opal content and diatom concentration at 351 and 411–431S coincide with highest pigment concentrations along the Chilean coast. Predominance of the diatom species Thalassiosira pacifica and T. poro-irregulata, and higher relative contribution of the silicoflagellate Distephanus speculum at 41°–43°S suggest the influence of more nutrient-rich waters and low sea surface temperatures, probably associated with the Antarctic Circumpolar Water.

- by Oscar E Romero
- •
- Environmental Science, Environmental Studies, Palaeoecology, Diatoms

In order to determine water quality status in the Duero basin (NW Spain), epilithic diatom samples were collected and analyzed in 137 stations in August 2004 following normalized standard protocols. The floristic particularities of the diatom assemblages in the basin are discussed. A total of 429 diatom taxa were identified in the basin and 90 taxa (21%) were new for the Iberian Peninsula. Especially noticeable was the presence of Achnanthidium rivulare, only known until now from North America. Ordination revealed the existence of five species assemblages related to the following environmental factors: 5-Day Biochemical Oxygen Demand (BOD5), [PO43-], and conductivity. Light and scanning electron microscopy micrographs are provided for some common, infrequent or exotic diatom species present in the Duero basin. Three diatom indices (Specific Pollution Index SPI, European Index CEC and Biological Diatom Index BDI) were applied. All of them correlated significantly with water physical and chemical variables, but SPI achieved the best correlations, and is therefore recommended as the reference diatom index for this Mediterranean basin.

- by Saúl Blanco
- •
- Phycology, Bioindicators, Stream ecology, Taxonomy

"En este trabajo se ha realizado una aplicación que extrae automáticamente las principales características geométricas de las algas diatomeas. Estas algas resultan de gran utilidad en la monitorización de la calidad de las aguas, de ahí la importancia que la automatización de los procesos de análisis conlleva. La aplicación extrae 15 descriptores geométricos de
cada diatomea almacenando su valor tanto en píxeles como en micrómetros. Se obtiene también la presencia o no del estigma al ser éste un valor determinante en la clasificación. Para llegar a este resultado es necesario realizar con anterioridad una segmentación autónoma de las imágenes digitales obtenidas mediante fotografía digital. Dicha
segmentación autónoma requirió del desarrollo de un método específico basado en la combinación de dos técnicas: binarización por umbralización y detección de bordes utilizando el filtro de Canny. La separación de objetos solapados se resolvió mediante un método que combina binarizaciones, filtrados, adelgazamientos, operaciones morfológicas y el detector de bordes de Canny. Los valores
geométricos calculados se compararon con los resultados proporcionados por un experto, tras realizar las mediciones de forma manual. Los resultados son muy similares por lo que se considera correcto el desarrollo realizado."

- by Saúl Blanco and +1
- •
- Phycology, Geometric Morphometrics, Stream ecology, Taxonomy

In 2009, seventeen analysts participated in a pan-European diatom ring-test (intercalibration), analyzing nine samples from seven countries following the European standard EN 14407. The objective of this exercise was to agree on practical conventions on diatom identification to facilitate future intercalibration work and to assess the extent to which national differences in sample analysis (counting protocol and identification conventions) contribute to variability in EU-level comparisons of diatom-based methods. Differences in the reported taxa lists were large, but not a major source of variation in values of a common metric (the phytobenthos Intercalibration Common Metric, ICM). Therefore, every country can apply its own identification conventions for national assessments, and still be fairly confident that the ICM reflects the national classification of its streams. Part of the index variation was due to differences in counting protocols and care should be taken when handling broken valves, girdle views and small taxa. More work at both national and European level is needed to provide a harmonized way of using diatoms for ecological status assessments in the future.

- by Luc Denys and +1
- •
- Phycology, Stream ecology, Taxonomy, Algae

Two Mastogloia Thwaites ex W.Sm. taxa were found during a survey of the diatom flora of Lac de Guiers, Senegal. Based on all currently available literature, one taxon could be identified as M. belaensis M.Voigt, a species formerly described from Pakistan. The second species showed some resemblance to M. braunii Grunow. Analysis of the type of M. braunii revealed, however, important morphologic differences, leading to the description of a new species from the Senegal population: M. senegalensis Van de Vijver, Fofana, Sow \& Ector sp. nov. The present paper describes this new species and discusses and illustrates the morphology of M. belaensis and the type of M. braunii. All taxa are discussed with morphologically similar taxa.

- by Saúl Blanco and +1
- •
- Diatom taxonomy, Diatoms, Phycology diatoms algae, Benthic Diatoms
- by Saúl Blanco
- •
- Phycology, Bioindicators, Stream ecology, Taxonomy

"Hippodonta lange-bertalotii Van de Vijver, Mataloni & Vinocur sp. nov. is described from Crater
Lake, Deception Island (South Shetland Islands). Present paper reports a detailed morphological descrip-tion of this species by means of light and scanning electron microscopy. The main diagnostic criteria in-clude the rhombic outline of the valves, the comparatively narrow striae and the presence of two shortened
striae delimiting the central area. The adscription of this new species to the genus Hippodonta and the
differences with related taxa are briefl y discussed. Additionally, the morphological variability of the similar
H. pseudacceptata is examined analyzing the valvar ultrastructure of different populations collected from
Western Europe or published in the literature. Hippodonta pumila is presented as a heterotypic synonym
of H. pseudacceptata."

- by Saúl Blanco and +1
- •
- Phycology, Systematics (Taxonomy), Stream ecology, Taxonomy

"Cambodian aquatic ecosystems are extremely diversified and constitute major preservation targets. However,
the species composition, diversity, and distribution of the inhabiting algal communities are largely unknown.
During a sample collection carried out in the Angkor and Banteay Srei monuments area in 2010, several unknown
diatom taxa were found in various population densities in the artificial lakes surrounding these temples. Detailed light
and scanning electron microscopy observations allowed the description of five of them (Pinnularia cambodiana, P.
shivae, Gomphonema angkoricum, G. paradaphnoides, and Frustulia lacus-templi) as taxa new to science. Differential
diagnostic criteria with respect to similar taxa, together with the ecological and environmental implications of
these findings, are briefly discussed."

- by Saúl Blanco
- •
- Phycology, Systematics (Taxonomy), Cambodia, Stream ecology
- by Agata Wojtal
- •
- Phycology diatoms algae, Diatom Taxonomy and Ecology
- by Saúl Blanco
- •
- Phycology, Stream ecology, Taxonomy, Invasive species ecology

For bioassessment of freshwaters, diatom indices have been mainly used in streams although their applicability in shallow lakes has been demonstrated in several studies. However, the influence of sampling substrata on periphytic diatom communities and on the ecological quality inferred from them has been paid little attention. In this paper, we test the ‘neutral substrate hypothesis’, which predicts no relevant influence of host plant type on their epiphytic community. Nineteen shallow permanent lakes from north-west Spain were studied and classified into three trophic levels. Epiphytic diatom communities growing on three different macrophytes for each trophic level were sampled and analysed. We assess: (1) which of the most common diatom indices provides a reliable water quality assessment, (2) how different plant substrata influence the diatom communities growing on them and (3) how these differences affect water quality assessment. Similarity tests showed significant differences in the composition of diatom assemblages among nutrient concentrations and host macrophytes. In contrast, ANOVA results for selected diatom-based metrics showed significant differences among trophic levels but not between different plant substrata. This supports the use of epiphytic diatoms as biological indicators for shallow lakes irrespective of the dominant macrophyte.

- by Cristina Cejudo Figueiras and +1
- •
- Phycology, Limnology, Bioindicators, Stream ecology

"The diatom generic name Detonia Frenguelli, 1949, is a
later homonym of the fungal name Detonia Saccardo, 1889.
The generic name Neodetonia is proposed here to replace
Detonia Frenguelli.
"

- by Saúl Blanco
- •
- Phycology, Stream ecology, Taxonomy, Ecology

Diatoms play a key role in the functioning of streams, and their sensitivity
to many environmental factors has led to the development of numerous diatombased
indices used in water quality assessment. Although diatom-based monitoring
of metal contamination is not currently included in water quality monitoring
programs, the effects of metals on diatom communities have been studied in many
polluted watersheds as well as in laboratory experiments, underlying their high
potential for metal contamination assessment. Here, we review the response of diatoms to metal pollution from individual level (e.g. size, growth form, and
morphological abnormalities) to community structure (replacement of sensitive
species by tolerant ones). These potential effects are then tested using a large,
multi-country database combining diatom and metal information. Metal contamination
proved to be a strong driver of the community structure, and enabled for the
identification of tolerant species like Cocconeis placentula var. euglypta, Eolimna
minima, Fragilaria gracilis, Nitzschia sociabilis, Pinnularia parvulissima, and
Surirella angusta. Among the traits tested, diatom cell size and the occurrence of
diatom deformities were found to be good indicators of high metal contamination.
This work provides a basis for further use of diatoms as indicators of metal pollution.

- by Saúl Blanco
- •
- Phycology, Water quality, Stream ecology, Taxonomy

During a biological survey carried out in five shallow, high-altitude saline lakes of the Bolivian Altiplano in 2009, six unknown diatom
taxa were found in various lake populations. Detailed light and scanning electron microscopy observations allowed the description of the
following new taxa: Navicula venetoides (distinguished from N. veneta Kützing by having coarser lineate striae), Pinnularia boliviana
(similar to P. rhombarea var. halophila Krammer but with coarser striae and a narrower central area), Nitzschia sansimoni (morphologically
close to N. supralitorea Lange-Bertalot, the latter having denser striae), Surirella striatula var. halophila (differing from the nominate and
other varieties in a distinctly heteropolar outline and the presence of denser fibulae) and S. moralesii (with large, strictly isopolar valves
and a deep pervalvar depression). Differential diagnostic criteria with respect to similar taxa, together with ecological and biogeographical
implications of these findings, are briefly discussed.

- by Saúl Blanco and +1
- •
- Phycology, Stream ecology, Taxonomy, Ecology

A unicellular marine microalga, Entomoneis sp. was isolated and studied as had become the dominant species compared to other bacillariophyta species in different environmental fluctuations in Izmir Bay. In effort to better understand the dynamics of this microalga that has achieved unprecedented domination, we conducted a monoculture isolation study. In this study, experiments were planned within the annual range of the Izmir Bay temperature, and the demonstrated behavior of the species in light and nutrient conditions. The stock culture medium was illuminated by approximately 50μmol photons m-2 s-1 of illumination with 14/24 daylight. The temperature of the climate chamber was set at the summer (T1 (21±1 o C)), spring (T2 (17±1 o C)) and winter (T3 (13±1 o C)) temperatures of Izmir Bay. Experiments were also conducted with four different light intensities (L1 (50 μmol photons m-2 s-1), L2 (25 μmol photons m-2 s-1), L3 (5 μmol photons m-2 s-1) and L4 (dark)). In this context, nutrient measurements were made on samples of the exponential, stationary and death phase of the culture and nutrient analyses were carried out. The results, which were designed according to ceteris paribus assumptions, were adapted to Michaelis-Menten kinetics. Consequently, considering the lifetime of the diatom at different temperature conditions, T3 was determined as an optimum temperature. Maximum growth rate and process time were observed at this temperature. This explains why these diatoms are abundant available in the winter. Once the light intensity was increased, the growth rate was increased at the T1 and T2 temperatures. However, T3 had a high growth rate at nearly L1 light intensity. Considering the consumption and transformation of different nutrient conditions, different results for both types of microalgae were obtained.

The transfer of Melosira cataractarum Hust. to the genus
Pseudostaurosira D.M. Williams & Round is presented based on a detailed analysis
of the type material from Java (Malay Archipelago) using light and scanning
electron microscopy. The species was initially described as a “centric” diatom
within the genus Melosira C. Agardh and was later transferred to the genus
Aulacoseira Thwaites. Pseudostaurosira cataractarum (Hust.) C.E. Wetzel, E. Morales
& Ector comb. nov. differs from other species of the genus by its smaller size,
typical radiate striae arrangement and absence of apical pore fields. We
additionally propose the transfer of Fragilaria sopotensis Witkowski & Lange-Bert.
to the genus Pseudostaurosira, a species that is morphologically similar to P.
cataractarum

- by Saúl Blanco
- •
- Diatom taxonomy, Diatoms as indicators, Diatoms, Phycology diatoms algae
- by Saúl Blanco
- •
- Phycology, Microscopy, Stream ecology, Taxonomy

Ecological research on algae from Algeria and in particular on freshwater and estuarine diatoms remains insufficient. The aim of our work is to contribute to the taxonomy and ecology of benthic diatoms from freshwaters and estuaries in Algeria. For this purpose, we studied two sites of water courses in north-western Algeria: El-Hammam stream at Mascara and the estuary of Cheliff river at Mostaganem. Our inventory of benthic diatoms during dry season at the middle of El-Hammam stream during April, June and August 2010 led to the identification of 44 cosmopolitan species, while 30 species occurred at the mouth of Cheliff river. 10 taxa were recorded for the first time in Algeria. Diversity values (Species richness, Shannon's index and Equitability index) for the two study sites are generally medium to low. The results of the 17 diatom-based metrics tested show that ROTT trophic index (TID) and the Trophic Diatom Index (TDI) best mirrored water quality, but a revision of taxa autecological values is required.

- by Saúl Blanco and +1
- •
- Bioindicators, Diatom taxonomy, Diatoms as indicators, Diatoms

Benthic diatoms have traditionally been used as bioindicators of aquatic ecosystems. Because diatom-based monitoring of water quality is required by European legislation, molecular-based methods had emerged as useful alternatives to classical methods based on morphological identification using light microscopy. The aim of this study was to test the reliability of DNA metabarcoding combined with High-Throughput Sequencing (HTS) techniques in the bioassessment of the trophic status of 22 Mediterranean shallow ponds in NW Spain. For each pond, the Trophic Diatom Index (TDI) was calculated from inventories obtained by identification using light microscopy (LM) followed by high-throughput sequencing (HTS) at the molecular level. Ponds were subsequently classified into five water quality classes. The results showed a good correspondence between both methods, especially after applying a correction factor that depended on the biovolume of the cells. This correspondence led to the assignment to the same quality class in 59% of the ponds. The determination and quantification of valves or DNA sequences was one of the main pitfalls, which mainly included those related to the variability in the relative abundances of some species. Accordingly, ponds with similar relative abundances for the dominant species were assigned to the same quality class. Moreover, other difficulties leading the discrepancies were the misidentification of some species due to the presence of semi-cryptic taxa, the incompleteness of the reference database and the bioinformatic protocol. Thus, the validation of DNA-based methods for the identification of freshwater diatoms represents an important goal, as an alternative to using traditional methods in Mediterranean shallow ponds.

- by Saúl Blanco
- •
- Diatoms as indicators, Diatoms, Phycology diatoms algae, Benthic Diatoms

Two new species of Luticola are described, both from the Wuling Mountains Area, central China,
based on light and scanning electron microscopy observations. Both new species have relatively small
valve dimensions for the genus. Luticola hunanensis sp. nov. possesses slightly protracted subrostrate ends
only in larger specimens; its slit-like stigma is always coupled with a tiny marginal pore; its proximal
and terminal raphe fi ssures are complex, both hooked towards the stigma-bearing side. In L. hunanensis
the number of areolae in each stria on the primary side is always greater than, or equal to, that on the
secondary side, and there is a row of rounded pores located on the mantle interrupted by the terminal raphe
fi ssures at the apices. Luticola wulingensis sp. nov. has produced rostrate ends and often exhibits a slightly
dorsiventral valve outline, its proximal raphe endings bend away from the stigma and its terminal raphe
fi ssures hook towards the stigma-bearing side; it has double rows of rounded pores located on the mantle
whereas at the apices the double rows become a single row interrupted by the terminal raphe fi ssures at the
apices. Both new taxa are epilithic and lives in freshwater habitats.

- by Saúl Blanco
- •
- Diatom taxonomy, Diatoms, Phycology diatoms algae, Benthic Diatoms
- by Eduardo A. Morales
- •
- Science Education, Diatoms, Phycology diatoms algae, South America