Diatom assemblages in Portuguese temporary rivers

During a survey of benthic diatoms in watercourses from Portugal in spring and summer 2006 and 2007, 76 sites in temporary streams (according to the National Water Institute classification) have been studied. These streams belong to the Ribeiras do Algarve (10 sites), Guadiana (19 sites), Mira (7 sites), Sado (16 sites), Tejo (20 sites), and Douro (4 sites) watersheds. Among these 76 sites, the National Water Institute classified only 48 as reference sites, and only these were therefore considered in the statistical analysis performed. A total of 276 diatom taxa have been identified in the 48 reference sites, from which 112 were present in abundance above 2% in at least one inventory. The most frequent taxa, present in more than 50% of the studied sites, were Achnanthidium minutissimum (Kützing) Czarnecki, Amphora pediculus (Kützing) Grunow, Cocconeis euglypta Ehrenberg, Eolimna minima (Grunow) Lange-Bertalot, Gomphonema parvulum Kützing, G. rosenstockianum Lange-Bertalot & E. Reichardt, Navicula gregaria Donkin, N. veneta Kützing, Nitzschia inconspicua Grunow and Planothidium frequentissimum (Lange-Bertalot) Lange-Bertalot. These are neutrophilous to alcaliphilous, mesosaprobous to -meso-saprobous, eutraphentic to indifferent taxa. Furthermore, a multivariate analysis relating diatom assemblages with environmental parameters is presented and the ecological preferences of not yet well known taxa, such as G. rosenstockianum, are provided

On the nomenclatural validity of Achnanthidium subatomoides (Bacillariophyta)

P. 165-166On the nomenclatural validity of Achnanthidium subatomoides (Bacillariophyta)S

Staurosira magallanesica, a replacement name for Staurosira patagonica

Staurosira patagonica M.L.Garcia, Maidana, Ector & E.Morales described a new species found in material of Maar Magallanes, Patagonia, Argentina and other lakes in southern Patagonia. This new species was analysed in detail by light and electron microscopy and a comprehensive description is given in Garcia et al. (2017: 107, 114, figs 2-45). However, this name is a later homonym of Staurosira patagonica Cleve, 1882. If we compare our species to Cleve’s illustration (Cleve 1882: pl. 16: fig. 13), we can easily differentiate the two by their general valve outline and morphometric data. As pointed out by Garcia et al. (2017), re-examination of the type material of members of the Fragilariaceae is needed to confirm identities, establish taxonomic boundaries and to facilitate identification, and this is also the case with Staurosira patagonica Cleve. A new name is, however, required for Staurosira patagonica M.L.Garcia, Maidana, Ector & E.Morales as it is an illegitimate name: Staurosira magallanesica M.L.Garcia, Maidana, Ector & E.Morales nom. nov. Replaced synonym: Staurosira patagonica M.L.Garcia, Maidana, Ector & E.Morales Nova Hedwigia, Beiheft 146: 107, 114, figs 2-45, 2017, nom illeg., non Staurosira patagonica Cleve 1882 Öfversigt af Kongliga Svenska Vetenskaps-Akademiens Förhandlingar 38(10): 13, pl. 16: fig. 13, 1882 ‘1881’. Etymology: we have derived the specific epithet from the name of the paleolake Maar Magallanes where this new species was found for the first time by N.I. Maidana (Maidana & Corbella 1997).Fil: García, María Luján. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: Maidana, Nora Irene. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: Ector, Luc. Luxembourg Institute of Science and Technology; LuxemburgoFil: Morales, E. A.. Universidade de Évora; Portuga

MORPHOLOGICAL DIVERSITY WITHIN THE ACHNANTHIDIUM MINUTISSIMUM SPECIES COMPLEX

During a survey of benthic diatoms sampled in watercourses from Mainland Portugal, several Achnanthidium populations morphologically ascribable to the A. minutissimum complex have been found. They clearly belong to the genus Achnanthidium on the basis of the valve outline, radiate striae, uniseriate, wider spaced striae in the centre of the valve and cells shallow‐V‐shaped in girdle view. The raphe valve has a straight central raphe hardly expanding at the centre and a row of elongated areolae in the mantle. Within the genus Achnanthidium these morphotypes belong to the complex of A. minutissimum (Kützing) Czarnecki, due to their straight terminal raphe fissures, in opposition to the species with terminal raphe fissures clearly deflected on the same side of the valve. Since these individuals were abundant in numerous sites, especially in the Centre and North of Portugal, a more detailed examination was performed by means of light (LM) and scanning electron microscopy (SEM). Furthermore, the examination of the environmental characteristics of the sites where they have been sampled allowed us to gather sufficient information on the ecological preferences of the different taxa. The main features that allow the separation of these taxa among each other and from all the other known Achnanthidium species are the different valve outline and dimensions, the size and shape of the central area, the apices shape and the density of the striae throughout the valve and near the apices. The LM and SEM analyses of the type materials of Achnanthidium microcephalum Kützing, Achnanthes minutissima Kützing and A. minutissima var. cryptocephala Grunow in Van Heurck have been done in order to help to clarify the taxonomy of this group. A comparison with the literature on Achnanthidium minutissimum species complex was performed, but the new Portuguese Achnanthidium taxa present a set of distinct morphological and ecological features that separate them well from all other similar species. Furthermore, two of these taxa have already been recorded from French watercourses with similar environmental characteristics

Epiphytic diatoms as water quality indicators in Spanish shallow lakes

P. 71-79The 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 effective-ness 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 correla-tion being lower with respect to the total phosphorus concentration. The classifica-tion 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 pa-rameters of the studied systems. Despite the use of these indices has been traditio-nally limited to rivers and channels, our results show the effectiveness of epiphytic diatoms as biological indicators of the quality of water in Mediterranean shallow la-kes and the applicability of common diatom indices for biomonitoring purposes in these aquatic ecosystemsS

Didymosphenia geminata (Bacillariophyta, Gomphonemataceae), una amenaza para nuestros ríos

p. 3-6Las diatomeas son un tipo de algas microscópicas unicelulares que habitan en ambientes acuáticos de todo el mundo. En los ríos forman un componente importante de la pátina mucosa que aparece sobre las rocas del lecho. Hasta hoy se han descubierto miles de especies de diatomeas sólo en las aguas dulces europeas y, como la mayoría de microorganismos, se supone que tienen distribución cosmopolita (FIN-LAY, 2002), si bien recientes estudios cuestionan esta idea (KOCIOLEK & SPAULDING, 2000; FOISSNER 2006). Hoy se reconoce la existencia de diatomeas exóticas e invasoras de reciente aparición en Europa (COSTE & ECTOR, 2000). Didymos-phenia geminata (Lyngbye) (Schmidt, 1899) es una diatomea descrita por primera vez en las Islas Faroe en 1819S

Looking back, looking forward: a review of the new literature on diatom teratological forms (2010–2020)

AbstractOver the last years, issues concerning diatom teratological forms and environmental stress have received growing interest within the scientific community. Publications on this topic dated back to 1890 and were summarized in a review published in 2009 by the journalHydrobiologia, accounting for high citation rates (i.e. 117 citations Scopus and 232 citations Google Scholar, October 2020). This wide interest stimulates the authors to further unravel teratological forms significance in the light of the most recent publications (2010–2020). Diatom teratological forms are one of the best individual-level biomarkers since they provide a rapid response to several environmental stressors, including new emerging pollutants. The mechanisms involved in teratological valve likely involve both cytoskeleton and silicon metabolic pathway impairments. However, teratologies do not seem to weaken the reproduction capacity and viability of the affected individuals. We recognized eight types of teratologies as involving different parts of the valve, depending on genus. In order to summarize the information obtained by several years of research, we suggest a four-step procedure aimed at providing a theoretical pathway that researchers should follow to better explain results obtained in next-future studies and representing a starting point for the development of an environmental index based on teratological forms

Estudio comparativo del estado ecológico de los ríos de la cuenca del Ebro mediante macroinvertebrados y diatomeas

Se ha estudiado durante el verano de 2002 el estado ecológico en 87 estaciones de muestreo repartidas a lo largo de la cuenca del Ebro (España) mediante diferentes índices bóticos de macroinvertebrados y diatomeas. La mayor parte de las estaciones analizadas alcanzaron al menos un nivel de estado ecológico "Bueno", pero se vieron algunas diferencias entre los distintos tipos fluviales existentes, teniendo una mejor calidad aquellos tipos correspondientes a zonas de cabecera y ríos de montaña. En general las estaciones con un estado ecológico peor correspondían a tramos bajos de ríos cercanos a núcleos urbanos e industriales, zonas con importante actividad agrícola y ganadera o tramos por debajo de embalses. Se ha observado una correlación positiva significativa entre los índices de macroinvertebrados y diatomeas empleados, tanto en lo concerniente a los valores obtenidos, como respecto a las clases de estado ecológicas resultantes.During the summer of 2002 the water ecological status of 87 sample stations of different rivers along the Ebro River basin (Spain) was studied using different biotic indices based on benthic macroinvertebrates and diatoms. Most of the sample points studied in 2002 reached at least a "Good" ecological status but some differences between the different existing fluvial types were observed. Upper river stretches and mountain rivers had higher ecological status. In general the sampling stations with the worst ecological status level were mainly located downstream, close to urban and industrial areas, near agricultural or livestock areas or downstream dams. A positive, significant correlation was observed between macroinvertebrate and diatom indices, both concerning the values obtained and the resulting ecological status categories

Fragilaria odeloucaensis sp. nov. (Bacillariophyta, Fragilariaceae) a diatom from temporary streams in southern Portugal

A new species of araphid diatom is described from a temporary stream in southern Portugal, Fragilaria odeloucaensis sp. nov., which belongs to the group of Fragilaria with widely linear to lanceolate valve outline, spaced striae, lacking spines, and with well-developed apical pore fields. The new taxon can be distinguished based on five unique features within this group, the lanceolate valves with capitate apices, the zig-zagged axial area, the central area with squared fascia, the apical pore fields clearly sunken into the valve apices and the heterovalvar frustules (with respect to striae distancing). Ecological features of the type locality and an additional sampling point where the new species was found are given, together with a discussion of the taxonomic position of the new species within Fragilaria, and the approach used herein for the identification of diagnostic features. This approach includes a detailed analysis of the internal and external characteristics of the axial areavirgae-striae complex, central area, apical pore fields and differences among valves of the same frustule, in addition to the traditional valve shape and morphometric features.This work was co-funded by the Science and Management of Intermittent Rivers & Ephemeral Streams (SMIRES) COST Action (CA 15113), http://www.smires.eu, the European Union through the European Regional Development Fund, framed within the Operational Programme Competitiveness and Internationalization, COMPETE 2020 through the ICT project (UID /GEO /04683/2013) with reference POCI -01-0145-FEDE R-007690, and the Agência Portuguesa do Ambiente, APA-000004DFIN .AA LP/2017 integrated within the Operational Program for Sustainability and Efficiency in the Use of Resources 2014-20, POSEUR-03-2013-FC-000001. Co-funding was also provided within the framework of the DIATOMS project (LIST - Luxembourg Institute of Science and Technology)

On some common and new cavum-bearing Planothidium (Bacillariophyta) species from freshwater

[EN] Thirteen Planothidium species are illustrated and discussed in a detailed morphological account based on light and scanning electron microscopy analysis of modern and historic materials related to the names Planothidium rostratum (Østrup) Lange–Bertalot and Planothidium frequentissimum (Lange–Bertalot) Lange–Bertalot. Eight species from freshwater environments in Europe, Asia and South America are proposed as new. All taxa here discussed and illustrated belong to the group of species characterized by the presence of a cavum in the rapheless valve. Additional information concerning their distribution and ecology is briefly commented based on a thorough literature revisionSIThis study was realized in the framework of the project DIATOMS of the Luxembourg Institute of Science and Technology (LIST). We gratefully acknowledge Denise C. Bicudo (Instituto de Botânica de São Paulo, Brazil), Friedel Hinz (Friedrich–Hustedt–Zentrum für Diatomeenforschung, Bremerhaven, Germany), Martin Kelly (Bowburn Consultancy, Durham, UK), Rémy Marcel (AQUABIO, Cournon d’Auvergne, France), Marina Potapova (The Academy of Natural Sciences, Diatom Herbarium, Philadelphia, PA, USA), Jeanne Rigaut (GREBE, Groupe de Recherche et d’Etudes Biologie et Environnement, Lyon, France), Francois Straub (PhycoEco, La Chaux–de–Fonds, Switzerland) and Frank Véry (DREAL Auvergne–Rhône–Alpes, France) for providing materials. The Vlaamse MilieuMaatschappij (VMM, Belgium) is also thanked for providing some of the analysed sample