Diatoms as indicators Research Papers (original) (raw)

Foreword to the English Edition After the time known informally by diatomists as the “Era of the Green Books” (i.e. the Süßwasserflora) which lasted about until the mid 1990s and during which all the information one needed to have to... more

Foreword to the English Edition
After the time known informally by diatomists as the “Era of the Green Books” (i.e. the Süßwasserflora) which lasted about until the mid 1990s and during which all the information one needed to have to address the central European diatom microflora was included in four books, there was an explosion of new publications as fundamental concepts underpinning the taxonomy of diatoms were revised, a large number of new species were described, and many familiar taxa bounced between genera. These are exciting times for those interested in the phylogeny,
biogeography and diversity of diatoms, but also hugely frustrating times for those concerned with the routine identification of diatoms for practical purposes. Application of the EU WFD needs a consistent approach to the naming of the organisms upon which assessments depend. HOFMANN et al. (2011) represented a welcome exception to the trend of an ever-more diffuse literature on diatoms, since it gave analysts, once again, a single identification text for the species most likely to be found during routine assessments in central Europe.
In order to facilitate use outside the German-speaking area, we decided to translate this work into English. At the same time, the lead Editor used this opportunity to update the work to include the latest information on the taxonomy and ecology. Decisions on revisions were made following a very empirical criterion: all taxonomy and ecology papers of which we are aware published until autumn 2016 were considered, and all genera and species (if quantitatively relevant)
were included if they appeared to be recognized in the main online resources (in particular, ‘Diatoms of the Unites States’, ‘AlgaeBase’ etc.), and by the community of diatomists. This is a very practical criterion, which might sometimes lead to inclusion of taxa whose merits are
still being debated, as long as it appears that they still might have some useful application in everyday practice and some recognition in applied ecology.
Following this process, 26 genera were included in the updated English edition of the book whilst in just three cases genera that were included in the first (German) edition have been removed (although they are still mentioned and briefly explained in the book). 10 species have been added to the book, 27 more have been newly mentioned under ‘Similar taxa’, taxonomic concepts were clarified / updated for 36, and 39 were transferred from one genus to another. The clarification and updating made it necessary to produce new identification keys for two
genera (Diploneis and Sellaphora). Information on plastids (only occasionally available in the German edition) has been added whenever possible to the descriptions of the genera. Terminology of both taxonomic features and also ecological concepts was updated in the Glossary. We have also improved the information on ecology and distribution for 22 species. These improvements to the text are accompanied by several additional references. Formal taxonomic
changes were carried out only when strictly necessary in order to simplify difficult situations or improve the rationale of genus affiliation: one new species description (of a morphologically distinct Sellaphora of waters of high saprobic level), seven formal transfers (comb. nov.), one
formal name changes (nom. nov.). The full text of the species descriptions of the German edition has been replaced by more schematic profiles, in which the different points are provided
in a “bullet point” style. This replaces the rich German prose, capable of conveying even nuances of the morphology, with something far more accessible to international audiences.
This English edition, like the earlier German ones, is intended primarily as a tool to facilitate consistent and accurate identification of diatoms in central Europe. We are, however, confident that it might be of general interest for all those looking for an up-to-date overview of most freshwater benthic diatom genera and of the characteristics of their most commonly encountered species.
Marco Cantonati & Martyn Kelly

Science popularization paper briefly introducing the diatom identification volume: Freshwater Benthic Diatoms of Central Europe (FBDCE): Over 800 Common Species Used in Ecological Assessment. M. Cantonati, M.G. Kelly & H. Lange-Bertalot... more

Science popularization paper briefly introducing the diatom identification volume: Freshwater Benthic Diatoms of Central Europe (FBDCE): Over 800 Common Species Used in Ecological Assessment. M. Cantonati, M.G. Kelly & H. Lange-Bertalot (Eds.): 942 pp. Koeltz Botanical Books (ISBN 978-3-946583-06-6). English edition with updated taxonomy and added species of: Hofmann G., Werum M. & Lange-Bertalot H. 2013. Diatomeen im Süßwasser-Benthos von Mitteleuropa. Bestimmungsflora Kieselalgen für die ökologische Praxis. Über 700 der häufigsten Arten und ihre Ökologie. Lange-Bertalot, H. (Ed.): 908 pp. 2. korrigierte Aufl. Koeltz Botanical Books.
The principal goal of this volume is to provide an effective tool for diatom identification in applied ecology (diatom-based assessments and monitoring, environmental sciences etc.).

In the austral summer of 2006/7 the ANDRILL MIS (ANtarctic geological DRILLing-McMurdo Ice Shelf) project recovered a 1285 m sediment core from beneath the Ross Ice Shelf near Ross Island, Antarctica in a flexural moat associated with... more

In the austral summer of 2006/7 the ANDRILL MIS (ANtarctic geological DRILLing-McMurdo Ice Shelf) project
recovered a 1285 m sediment core from beneath the Ross Ice Shelf near Ross Island, Antarctica in a flexural
moat associated with volcanic loading. The upper ~600 m of this core contain sediments recording 38 glacial/
interglacial cycles of Early Pliocene to Pleistocene time, including 13 discrete diatomite units (DUs). The
longest of these, DU XI, is ~76 m-thick, and has been assigned an Early to Mid-Pliocene age (5–3 Ma). A
detailed record of the siliceous microfossil assemblages in DU XI is used in conjunction with geochemical and
sedimentological data to subdivide DU XI into four discrete subunits of continuous sedimentation. Within
each subunit, changes in diatom assemblages have been correlated with the δ18O record, providing a temporal
resolution up to 600 yr, and allowing for the construction of a detailed age model and calculation of associated
sediment accumulation rates within DU XI. Results indicate a productivity-dominated sedimentary record
with greater proportions of hemipelagic mud accumulating during relatively cool periods. This implies that
even during periods of substantial warmth, Milankovitch-paced changes in Antarctic ice volume can be linked
to ecological changes recorded in diatom assemblages.

Diatom algae are known to play an important role as primary producers in many diverse ecosystems including artificial aquaculture ponds were they also aid in maintaining water quality by consuming excess nutrients. But factors influencing... more

Diatom algae are known to play an important role as primary producers in many diverse ecosystems including artificial aquaculture ponds were they also aid in maintaining water quality by consuming excess nutrients. But factors influencing their growth are still poorly understood. In the present study the effect of micro nutrients, N: P ratio and silica concentration on benthic diatom Synedra sp. grown in fish pond waste water was studied along with nutrient removal efficiency. We have studied 9 different treatments of which addition of micronutrient mixture Nualgi along with adjusted N:P to 6:1 has resulted in highest cell density followed by Silicate enrichment were as only N:P adjustment and Nualgi addition has no significant effect on diatom growth. At the end of growth experiment, the N removal efficiency of treatment groups (50.23%–65.44%) were significantly higher (P < 0.05) than control group (43.56%) were as phosphate removal efficiency was significantly higher (P < 0.05) with Nualgi and N:P adjustment (53.37%–68.98%). The silicate consumption was significantly higher in control group at 63.87%, than other experimental groups. These results will give us a new insight in to important factors influencing beneficial algae growth and simultaneous nutrient removal from aquaculture waste water.

High-resolution images of phytoplankton cells such as diatoms or desmids, which are useful for monitoring water quality, can now be provided by digital microscopes, facilitating the automated analysis and identification of specimens.... more

High-resolution images of phytoplankton cells such as diatoms or desmids, which are useful for monitoring water quality, can now be provided by digital microscopes, facilitating the automated analysis and identification of specimens. Conventional approaches are based on optical microscopy; however, manual image analysis is impractical due to the huge diversity of this group of microalgae and its great morphological plasticity. As such, there is a need for automated recognition techniques for diagnostic tools (e.g. environmental monitoring networks, early warning systems) to improve the management of water resources and decision-making processes. Describing the entire workflow of a bioindicator system, from capture, analysis and identification to the determination of quality indices, this book provides insights into the current state-of-the-art in automatic identification systems in microscopy.

Diatom assemblages in carbonate spring habitats at low elevations, with low discharge, and affected by direct human impacts were studied only recently and in some geographic areas. We describe and characterize the ecology of a new... more

Diatom assemblages in carbonate spring habitats at low elevations, with low discharge, and affected by direct human impacts were studied only recently and in some geographic areas. We describe and characterize the ecology of a new Navicula species from springs with these characteristics within the basin of the River Adige in the south–eastern Alps and Alpine foothills (Province of Verona, Italy). Navicula veronensis sp. nov. is in the group of species around N. cincta but has distinct outline, size, central area, and proximal raphe endings. The availability of data on the distribution of the new species in streams of the Island of Cyprus allowed to quantitatively compare the ecological preferences, niche position, and niche breadth of Navicula veronensis sp. nov. with those of allied species. The new species was found to be characteristic of medium–high conductivity freshwaters, rich in sulphates and chloride, often nitrate enriched and affected by marked discharge fluctuations and seasonal desiccation. Niche position however differed only slightly from those of morphologically–similar species, with the exception of Navicula dealpina that was found to be characteristic of oligotrophic, calcium– bicarbonate rich environments with medium(–low) conductivity. Canonical Correspondence Analysis clearly showed that the most influential environmental variables determining the diatom assemblages of low–elevation carbonate springs affected by anthropogenic disturbance were nitrate enrichment, spring morphology alteration (in particular for water abstraction), and low discharge.

Diatoms are one of the key organisms used in biomoni-toring studies and they occur in a wide variety of environments , exhibiting a broad range of tolerance to abiotic factors. Historically, the first freshwater diatom study in Turkey was... more

Diatoms are one of the key organisms used in biomoni-toring studies and they occur in a wide variety of environments , exhibiting a broad range of tolerance to abiotic factors. Historically, the first freshwater diatom study in Turkey was conducted in 1844 by Ehrenberg based on the material collected from the Murat and Aras Rivers. Situated between large continents (Eurasia and Africa), Turkey comprises areas of very diverse geological, climatic and environmental conditions, so we should expect that organisms such as diatoms show high diversity in this region. The aim of this study is to present new sites of rare and new records in Turkey from different genera along with morphological and ecological characteristics. As a result, a total of 73 species (24 rare and 49 new records) are presented in this study. Oceanological and Hydrobiological Studies, VOL. 45, ISSUE 4 | DECEMBER 2016 © Fa c u l t y o f O ce a n o gr a p hy a n d G e o gr a p hy, U n i ve r s i t y o f G d a ń s k , Po l a n d. A l l r i g h t s re s e r ve d.

On the basis of LM and SEM observations as well as of environmental data, three species of the predominantly-acidophilous diatom genus Eunotia (E. cisalpina, E. fallacoides, E. insubrica) are described as new to science, and characterized... more

On the basis of LM and SEM observations as well as of environmental data, three species of the predominantly-acidophilous diatom genus Eunotia (E. cisalpina, E. fallacoides, E. insubrica) are described as new to science, and characterized from the ecological point of view. The three new species were not distinguished from other similar ones in the past but can be identified at the LM by careful observation of diacritical characters such as valve outline (in particular the shape of the endings), dimensions, and stria density. One of the three new species (E. insubrica) presents a very peculiar ultrastructural feature, i.e. well-developed pseudoseptum-like structures at the apices. The three new species were pointed out by detailed analyses of materials sampled in the south-eastern Alps. It is put forward that diatom investigations adopting high-resolution taxonomy are particularly opportune in habitats such as those colonized by the three new species. The three new species were found...

Diatoms have become important organisms for monitoring freshwaters and their value has been recognised in Europe, American and African continents. If India is to include diatoms in the current suite of bioindicators, then thorough testing... more

Diatoms have become important organisms for monitoring freshwaters and their value has been recognised in Europe, American and African continents. If India is to include diatoms in the current suite of bioindicators, then thorough testing of diatom-based techniques is required. This paper provides guidance on methods through all stages of diatom collection from different habitats from streams and lakes, preparation and examination for the purposes of water quality assessment that can be adapted to most aquatic ecosystems in India.

Last year (2007) in Berlin the 21. Deutschsprachiger Diatomologen Treffen became at the same time the 1st Central European Diatom Meeting. This change was underlined by an evident increase in the number of participants. This trend... more

Last year (2007) in Berlin the 21. Deutschsprachiger Diatomologen Treffen became at the same time the 1st Central European Diatom Meeting. This change was underlined by an evident increase
in the number of participants. This trend continued with the second edition of the congress: The 2nd Central European Diatom Meeting in Trento. This was somewhat unexpected since this year (2008)
also the International Diatom Symposium will take place in a few months (07-13/09/2008) in Dubrovnik, Croatia, and several delegates announced that they would not be able to attend both meetings. In spite of this, as can be seen in Fig. 1, about hundred delegates registered for the Congress. It is therefore with satisfaction that we have the possibility to observe that their nationalities are very diverse, with an important contribution from non-German speaking countries
(Italy – “location effect” -, Czech Republic, Russia). We feel very honoured in acknowledging that some participants made long journeys to join our Congress, coming e.g. from Scotland, the eastern part of Russia, Israel, and Canada! Not surprisingly most of the participants work in Universities, but a significant share carries out its diatom investigations in other research institutions (e.g. Research Councils), and in Museums and Botanical Gardens (Fig. 2). This last observation is of special interest for us, since this year the Congress is organized in a Museum. In such Institutions, fundamental research (in particular
biodiversity documentation), collections, and educational issues and popularization are topics of prominent importance.
The topics covered by the contributions of the participants are diverse, but could be grouped into the categories shown in Fig. 3. These give an idea of ongoing diatom research in Central Europe. Not surprisingly biodiversity remains an important topic. Less obvious and – in our opinion encouraging – is the attention still given to taxonomy, a discipline which has difficulties in being acknowledged as a fundamental tool of ecological and applied research by administrators and decision makers.
In thanking the participants for coming to Trento and contributing to the Congress, we are happy that the Trentino Nature & Science Museum of Trento, a town that is not German speaking but that has always been a gate for those coming from Italy and approaching the German-speaking
area, can contribute to the continuation of the Central European Diatom Meetings, formerly Deutschsprachige Diatomologen Treffen.

Para facilitar y homogeneizar el tratamiento y la interpretación de la información generada en las redes de control biológico se presenta una colección de fichas descriptivas de los organismos fitobentónicos que incluyen: nombre... more

Para facilitar y homogeneizar el tratamiento y la interpretación de la información generada en las redes de control biológico se presenta una colección de fichas descriptivas de los organismos fitobentónicos que incluyen: nombre científico, común, sinónimo, propiedades, descripción, ecología, ruta taxonómica e índices y métricas, foto o ilustración incluyendo la propiedad y el autor. Esta guía ha sido elaborada por la Dirección General del Agua y forma parte de una colección de cinco tomos.

With 67 figures and 6 tables Cantonati, M., H. Lange-Bertalot, F. Decet & J. Gabrieli (2011): Diatoms in very-shallow pools of the site of community importance Danta di Cadore Mires (southeastern Alps), and the potential contribution of... more

With 67 figures and 6 tables Cantonati, M., H. Lange-Bertalot, F. Decet & J. Gabrieli (2011): Diatoms in very-shallow pools of the site of community importance Danta di Cadore Mires (southeastern Alps), and the potential contribution of these habitats to diatom biodiversity conservation. – Nova Hedwigia 93: 475–507. Abstract: Mires are very selective habitats, and the colonisation by specifically adapted organisms makes them very important both for nature conservation and environmental education. They have, however, been threatened by different types of impacts. Our objective was to study diatoms in stations representative of the main typologies in the Site of Community Importance IT3230060 "Danta Mires", also to produce data for a management plan in the frame of a Life Project. Five shallow pools within different mountain mires were sampled in summer 2005 and morphologically and physicochemically characterized. The sampled sites cover a rather wide pH and TDS content gradient with very low nitrate and silica values. Diatoms were found to dominate in terms of numbers of taxa, followed by desmids, cyanoprokaryotes and filamentous green algae. In total, 86 diatom taxa, belonging to 35 genera, were found. As expected for acidic, low-mineralization waters the genera with the highest number of taxa were Eunotia and Pinnularia, followed by Encyonema, Cymbopleura, Gomphonema, and Nitzschia. The most frequent and abundant taxa were: Frustulia crassinervia, Nitzschia acidoclinata, Kobayasiella micropunctata, Encyonema neogracile, Brachysira brebissonii, Nitzschia perminuta, and Encyonema lunatum. Taxa abundant only in one or few sites were: Eunotia paludosa, Staurosira spinarum, Encyonopsis cesatii, and Achnanthidium minutissimum. Several rare taxa of special interest for their distribution and/or rarity could be found (e.g. Chamaepinnularia schauppiana, Cymbopleura incertiformis var. linearis, C. subapiculata, Eunotia lapponica, Microfissurata paludosa). On average,

We studied diatoms from the fifteen springs selected in the Berchtesgaden National Park on be-half of the Bavarian State Ministry for the Environment to be sentinel environments of cli-mate-change effects. For three of these springs,... more

We studied diatoms from the fifteen springs selected in the Berchtesgaden National Park on be-half of the Bavarian State Ministry for the Environment to be sentinel environments of cli-mate-change effects. For three of these springs, diatom data based on samples taken in 1997 were also available. A total of 162 species belonging to 49 genera were found sampling three micro-habitat types (lithic materials, bryophytes, surface sediments). The cumulative percentage of all species included in a threat category including endangered species was 43%, confirming previ-ous findings for comparable environments of the Alps. We could find a statistically significant positive association between the Meinzer variability index for discharge and the cumulative rel-ative abundance of aerial diatom species. This study thus highlighted once again the relevance of discharge (and associated water-level) variability as an environmental determinant of diatom assemblages in spring ecosystems. Increased nitrate concentrations in some springs, likely due to diffuse airborne pollution and, locally, to impacts such as forest management, game, and cat-tle, led to a relevant occurrence of eutraphentic diatom species. Our results show a segregation of the older data in non-parametric diatom-based ordinations, suggesting a strong potential for the use of spring diatoms in studies aiming at tracking the effects of climate and environmental change.

Karst ecosystems are considered as priority environments for the protection of biodiversity on a global scale. This study provides a first comparative analysis of epilithic diatom flora from karst springs in two Mediterranean geographic... more

Karst ecosystems are considered as priority environments for the protection of biodiversity on a global scale. This study provides a first comparative analysis of epilithic diatom flora from karst springs in two Mediterranean geographic areas (Spain and Italy) with contrasting characteristics (islands vs mainland). We investigated twenty-three springs with different anthropogenic impact levels once in the winter season between 2007 and 2017 (N = 23). A total of 176 diatom taxa (56 genera) were found of which 101 (44 genera) were observed in single sites. A general good biotic integrity was revealed by structural indices (species richness, diversity and evenness). However, crenophilous species were generally present and abundant in less impacted springs. Comparing islands and mainland, significant differences were found in species composition and diversity (H') based on multivariate analyses (global R = 0.610; p = 0.001) and t-test (t = 2.304; p = 0.031). Discharge and Cl − were the most significant variables in determining diatom assemblages. Our results confirm the role of springs as multiple ecotones and refuges for rare species and suggest that the geographic insularity may be an important factor in maintaining diatom biodiversity.

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... more

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.

Time series of diatom assemblage composition can be obtained from samples of various collection materials. This allows assessment of ‘more natural’ conditions and their temporal variability in shallow lakes and ponds, similar to... more

Time series of diatom assemblage composition can be obtained from samples of various collection
materials. This allows assessment of ‘more natural’ conditions and their temporal variability in shallow lakes and
ponds, similar to traditional core–based palaeolimnology. Such information is useful to underpin restoration targets
that are ecologically relevant and that conform to legal requirements posed by the European Water Framework
Directive. Using sediment samples from herbarium macrophytes and other sources, historical conditions are
documented for a shallow man-made soft–water lake in lower Belgium (Kraenepoel, Aalter). Both assemblage
composition and diatom-inferred water chemistry varied considerably from 1853 to the first half of the 20th c. The
lake was used for pisciculture during this time. From this situation, two alternatives are envisaged to determine
the lake’s ecological potential, depending on whether it is kept hydrologically isolated or reconnected to the brook
that supplied its water originally. Later in the 20th c., inflow of polluted water and altered management caused
considerable eutrophication up to the time when restoration measures were undertaken (1999–2002). Since then
both diatom-inferred and measured physical-chemical conditions have improved considerably, even to the point of
approaching those in the early 20th c. Post-restoration sediment assemblages reflect some functional and structural
rehabilitation of the lake ecosystem, but return to a former species composition was limited. The most recent
observations (2006) suggest a possible reversal of the recovery process warranting further vigilance. The potential
of using sediment assemblages for monitoring lentic water bodies is highlighted.

"The Duero River Basin, with an area of 97290 km2 and more than 40000 km of streams, is the largest one in the Iberian Peninsula, and lies mainly under Mediterranean continentalized bioclimate. Aquatic ecosystems are endorheic and main... more

"The Duero River Basin, with an area of 97290 km2 and more than 40000 km of streams, is the largest one in the Iberian Peninsula, and lies mainly under Mediterranean continentalized bioclimate. Aquatic ecosystems are endorheic and main watercourses are regulated and highly anthropized. As in every lotic environment, benthic algae play a key role in the structure and functioning of its ecosystems and, within this group, diatoms represent the most abundant and diversified component. Their biological features make them excellent water quality indicators, and this has promoted their study at international level. As a result of the implementation of the Water Framework Directive of the European Union, ecological status biomonitoring networks have been established in all Iberian basins, based on the use, among others, of diatom indices, which has led to the need of more detailed taxonomic and ecological studies on these organisms. Despite their relevancy, such works are still scarce in Spain. In the Duero Basin, up to date more than 500 diatom species have been recorded, a high floristic richness that contrasts with analogue regions, this being related to the large diversity of environmental conditions included within this zone.
The aim of the present work is to elaborate a practical identification guide in accordance with the needs of technicians and biologists evaluating water biological quality in the Duero Basin. This book gathers the 200 main diatom taxa in terms of abundance and occurrence, selected from more than 600 samples of river epilithon collected during annual surveys carried out between 2003 and 2007 in the Spanish part of the basin. Certain taxa that could not be identified to specific level are also presented. For every diatom species, the following information is provided: a mor-phometric and autoecological description, a selection of illustrated bibliographic references and an iconographic series illustrating the taxon’s morphological variability, with a total of 3110 photographs in light and scanning electron microscopy gathered into 109 plates. The nomenclature, taxonomy and systematic position of taxa follow the most recent phycological literature. 116 species new to the Duero Basin and 34 species new to the Iberian Peninsula are presented."

– Springs are unique but understudied habitats. Diatom communities have received some attention but have remained largely unknown in the southwestern Alps. We therefore studied the springs of the southwestern extreme of the Alpine... more

– Springs are unique but understudied habitats. Diatom communities have received some attention but have remained largely unknown in the southwestern Alps. We therefore studied the springs of the southwestern extreme of the Alpine mountain range. We analysed epilithic and epiphytic assemblages in 48 springs of different ecomorpho-logical types, located on contrasting lithological substrata (carbonate/siliceous). Moreover , phytosociological relevés were carried out for carbonate springs. The diatom fl ora consisted of 223 taxa. Most (198) of the taxa were included in the Red List, and 12.5% belonged to threatened categories. Characteristic spring taxa (crenophiles) were present. The ecological preferences of crenophilous diatom species described in the eastern Alps were confi rmed. Diatom species characteristic of the lake-littoral zone were found in pool springs. We observed no signifi cant differences in species richness and diversity between epilithic and epiphytic assemblages, but some species showed a preference for bryophytes, and fi ve occurred in the epibryon only. As regards moisture conditions, 15% of the taxa occurred on wet or temporarily dry sites, and 4% lived mostly outside water bodies. The main environmental factors infl uencing diatom assemblages were pH, conductivity, altitude , and shading. The carbonate-substratum crenic vegetation was composed of a mixture of vascular plants and bryophytes, which fi nd their ecological optimum in springs. Bryo-phyte cover was dominant, with the most abundant taxa belonging to the genus Palustri-ella. The vegetation corresponded to the Cratoneuretum commutati association.

Given that diatom assemblages are a well-recognised method of characterising the water quality in freshwater streams, it seems reasonable to investigate its applicability to solar saltfields. A summer collection of benthic diatoms was... more

Given that diatom assemblages are a well-recognised method of characterising the water quality in freshwater streams, it seems reasonable to investigate its applicability to solar saltfields. A summer collection of benthic diatoms was undertaken in the salinas of the Dry Creek solar saltfields in South Australia for this purpose. The facility inputs seawater both from a low nutrient samphire creek and poorer quality, high nutrient samphire creek. Salinity and nutrient status of the pools and concentrating salinas have been thoroughly characterized over many years. The addition of JJ periphytometers to the sampling regime in the summer of 2001–2002 allowed the collection of benthic diatoms from these sites. Of the 69 species collected during the study, 16 species occurred only in oligotrophic waters with salinities less than 70 g/l TDS (total dissolved solids). Twenty species of diatoms occurred only in the eutrophic waters with salinities less than 70 g/l TDS, eight species were restricted to the hypersaline ponds and the remainder were undiscriminating in their ecological preferences.

We investigated the ultrastructure of Achnanthes delicatissima Simonsen in materials collected from the Swedish Baltic coast. Valve structure differs markedly from that of Achnanthes sensu lato, particularly in the absence of cribrate... more

We investigated the ultrastructure of Achnanthes delicatissima Simonsen in materials collected from the Swedish Baltic coast. Valve structure differs markedly from that of Achnanthes sensu lato, particularly in the absence of cribrate areolae which separates Achnanthes from all other members of the family Achnanthaceae. Comparing this species with those recently described achnanthoid genera, such as Scalariella Riaux-Gobin & Witkowski and Madinithidium Witkowski, Desrosiers & Riaux-Gobin revealed morphological differences that warrant the erection of a new genus, Navithidium. Owing to the small size of the frustules, it is difficult to identify Navithidium delicatissima in light microscopy due to similarities with some closely related taxa like Achnanthidium pseudochamaepinnularia (which is here transferred to Navithidium). A comparison with related genera is provided and discussed.

En esta obra se recogen los 200 taxones de diatomeas (pertenecientes a 60 géneros distintos) más importantes de las identificadas en más de 600 muestras de epiliton fluvial recogidas durante campañas de muestreo efectuadas entre 2003 y... more

En esta obra se recogen los 200 taxones de diatomeas (pertenecientes a 60 géneros distintos) más importantes de las identificadas en más de 600 muestras de epiliton fluvial recogidas durante campañas de muestreo efectuadas entre 2003 y 2007 en la parte española de la cuenca, dentro de los programas de seguimiento del estado de las masas de agua superficiales de la Confederación Hidrográfica del Duero. Esta selección atiende a un doble criterio, que valora la importancia de cada taxón dentro del inventario general de la cuenca, de forma que se han considerado las especies más abundantes y/o más ampliamente distribuidas en la zona de estudio; así como, por su interés florístico o biogeográfico, se incluyen algunos taxones adicionales (especies exóticas, poco conocidas o que representan novedades para la Península). Para cada especie se ofrece la siguiente información: una descripción morfológica y autoecológica (parte II), un mapa de distribución en la cuenca del Duero (parte III) y una serie de fotografías en microscopía óptica de campo claro donde se ilustra la variabilidad morfológica de cada taxón, reunidas en 36 láminas (parte II).

In situ effect of heavy metal enrichment on periphytic diatom community of a river was studied using metal diffusing substrates. Periphytic algae growing on these substrates showed intracellular accumulation of test metals (Cu, Zn and Pb)... more

In situ effect of heavy metal enrichment on periphytic diatom community of a river was studied using metal diffusing substrates. Periphytic algae growing on these substrates showed intracellular accumulation of test metals (Cu, Zn and Pb) which inhibited growth, as evidenced by reduced cell number, and increased morphological abnormalities in diatoms. In the case of Cu and Zn, percent deformed diatom frustules showed a strong relationship (r 2 > 0.80) with intracellular metal content and metal release from the substrate. Frustule deformity was evident in 15 of the 19 common diatom taxa, occurring frequently in Fragilaria capucina, Gomphonema parvulum, Nitzschia palea, Pinnularia conica and Ulnaria ulna. Altered pattern of striations and changed outline of frustules were the only deformities in the control; however, raphe modification and mixed deformities (several deformities in the same frustule) were additionally observed under metal stress. Raphe modifications were more frequent in the case of Cu exposure, while abnormalities in striations and mixed deformities were more prevalent in diatoms exposed to Zn or Pb. The present study shows the utility of morphological abnormalities in diatom frustules as an effective tool for biomonitoring of heavy metal pollution in waterbodies.

It is thought that long-term monitoring is an essential tool through which conservationists and managers (i) are alerted when the system departs from the natural state, (ii) can check their environmental policy, and (iii) can detect... more

It is thought that long-term monitoring is an essential tool through which conservationists and managers (i) are alerted when the system departs from the natural state, (ii) can check their environmental policy, and (iii) can detect disturbance effects. However, while long-term studies are growing in number, the lack of information on the background rates of natural changes could lead to a biased interpretation of results. In this study we analyzed the diatom composition of yearly samples (14 –16 yrs) in four springs with the following goals: (1) to estimate the consequences of sampling-related processes on the species composition and relative abundance; (2) to determine the form of the assemblages' variation, evaluating whether the assemblages can be predicted by cyclic, directional, or stochastic changes; (3) to test if, and to what extent, the diatom variability (variation in species composition, relative abundance and diversity) on a temporal scale is driven by the environment; (4) to evaluate the degree of temporal concordance among the diatom assemblages inhabiting four springs. Results showed that because the effect of sampling was inversely proportional to the species abundances, the presence of the least abundant species over the years were mainly a result of chance. The analyses allowed us to discriminate between stochastic and directional patterns, revealing the ongoing changes in two out of four springs. Because the environmental variables did not explain a significant portion of this variability, other hypotheses are put forward. The assemblages' dynamics of species composition over time were significantly synchronous in two out of six couples of springs, and regardless of the environment. This result can suggest that internal, within springs, drivers may be more important than extrinsic forces operating over regional spatial scales. Overall, these results provide a benchmark of diatom variability over time and in natural conditions delimiting the " limits of acceptable changes " .

ABSTRACT: Studies about prehispanic irrigation canals have an important role in the agricultural landscape reconstruction in archaeological investigations. However, these types of evidence are characterized in many areas by their low... more

ABSTRACT: Studies about prehispanic irrigation canals have an important role in the agricultural landscape reconstruction in archaeological investigations. However, these types of evidence are characterized in many areas by their low visibility and poor preservation, rendering difficult their recognition and subsequent study. For this reason, it is necessary to generate diverse independent methodologies. Therefore the study aims to propose a new methodological tool suitable for the use of biomarkers, such as diatom assemblages, for the identification and characterization of ancient irrigation canals. We have analyzed a furrow-like feature lying in proximity to the archaeological site of Peñas Coloradas (Antofagasta de la Sierra, Argentina), to evaluate which aspects of the diatom analysis (specific composition, absolute abundances, preservation stages of valves) are relevant to achieving this objective. Our results suggest that the analysis of the composition and abundance of diatom assemblages and their comparison with modern analogues was found to be useful for identifying the existence of ancient canals and thus, of archaeological water management. Besides, we have statistically proven that the degree of valve preservation was not a suitable tool for this type of investigation. This study has presented the first evidence for this type of archaeological hydraulic technology ever found in the locality and the sub-basin Las Pitas.

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.... more

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.

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... more

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.

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... more

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.

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... more

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.

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... more

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.

This paper gives a modern circumscription of Tropical/Subtropical diatoms regarding their relationship with sea-surface temperatures (SST) and sea ice cover. Diatoms from 228 core-top sediment samples collected from the Southern Ocean... more

This paper gives a modern circumscription of Tropical/Subtropical diatoms regarding their relationship with sea-surface temperatures (SST) and sea ice cover. Diatoms from 228 core-top sediment samples collected from the Southern Ocean were studied to determine the geographic distribution of eight major diatom species/taxa preserved in surface sediments generally located north of the Subantarctic Front. The comparison of the relative contribution of diatom species with modern February SST and sea-ice cover reveals species-specific sedimentary distributions regulated both by water temperatures and sea ice conditions. Although selective preservation might have played some role, their presence in surface and downcore sediments from the Southern Ocean are reliable indicators of high SST and poleward transport of waters from the Tropical/Subtropical Atlantic. Our work supports the use of diatom remains to reconstruct past variations of these environmental parameters via qualitative and transfer function approaches.

Coastal seas, and in particular estuarine systems, were significantly affected by Quaternary sea level changes. Furthermore, the dynamics of shelf and coastal evolution have had a strong impact on coastal landscapes inhabited by humans.... more

Coastal seas, and in particular estuarine systems, were significantly affected by Quaternary sea level changes. Furthermore, the dynamics of shelf and coastal evolution have had a strong impact on coastal landscapes inhabited by humans. The postglacial evolution of the vast North Sea shelf with its huge drainage systems, e.g. the Elbe Paleovalley and its tributary system, is an excellent research target to understand how coastal shelf environments change in response to sea level rise. In this study, we investigate infill sediments of the Paleo-Ems valley-a drowned extension of the modern Ems River and part of the Elbe Paleovalley drainage system. Radiocarbon-dated transgression sequences provide several new observations regarding the mode and rate of the river system submerging due to the Holocene transgression. Thus, the Paleo-Ems valley submerged within a short time span of~200 years since the river was not able to adjust its gradient to the rapid rising sea level. The fate of the Paleo-Ems is exemplary for the rapid change of a former fluvial landscape into a coastal landscape and finally into a submarine seascape.

The ability of sedimentary proxies (especially dung fungal spores) to reflect the past presence and density of large herbivores on a landscape has been receiving increasing scrutiny. Here we examine the Sporormiella spore record from a... more

The ability of sedimentary proxies (especially dung fungal spores) to reflect the past presence and density of large herbivores on a landscape has been receiving increasing scrutiny. Here we examine the Sporormiella spore record from a well-dated, multi-proxy, highly organic sedimentary record from the small lake basin of Marcacocha in the Cuzco region of Peru. The basin, a wetland since ca. AD 1840, existed as a small lake for at least 4000 years prior. Previous work at Marcacocha has shown that changes in herbivore densities reflect the abundances of oribatid mites preserved in the lake sediments. This study tests the assumption that both the Sporormiella and the oribatid mite records responded in broadly the same way to changes in herbivore densities over the past 1200 years.
Analysis reveals a very low covariance between concentrations of Sporormiella spores and the two major components of the oribatid mite assemblage: a single aquatic species of Hydrozetes and a less abundant, wider grouping comprising members of the mostly terrestrial superfamily Ceratozetoidea (referred to as the ‘ceratozetoids’). Variations in the Hydrozetes assemblage clearly dovetail with known historical events, including the massive decline of indigenous and camelid populations following the collapse of the Inca Empire in the mid-sixteenth century. Comparison with other environmental proxies from the Marcacocha sequence, including diatoms and charophyte oospores, suggests that the ceratozetoids appear to reflect increasing terrestrialization. In contrast, although the Sporormiella record indicates the presence of livestock, it fails to register the major historical changes in herbivore presence, though reflects well episodes of lake-level lowering. In small lake settings, therefore, the use of Sporormiella to estimate the density of herbivores in the catchment might be considered a relatively blunt instrument when compared with some other indicators.

Periphytic diatom index for assessing the ecological quality of the Colombian Andean urban wetlands Five wetlands in Bogotá (Guaymaral, Jaboque, Juan Amarillo, Santa María del Lago and Tibanica) and one rural wetland (Meridor, Tenjo... more

Periphytic diatom index for assessing the ecological quality of the Colombian Andean urban wetlands Five wetlands in Bogotá (Guaymaral, Jaboque, Juan Amarillo, Santa María del Lago and Tibanica) and one rural wetland (Meridor, Tenjo municipality) were sampled four times during dry, rainy and transitory climatic periods (between 2007 and 2008). Physico-chemical variables were measured and periphyton was sampled to evaluate the diatom community. The pollution value per taxon (PVT) was established for each diatom species and a periphytic diatom index for Bogotá Wetlands (PDIBW) was calculated to evaluate the ecological quality of the wetlands. According to the limnological status thus established, the six wetlands can be classified as follows: Santa María del Lago, Meridor and Jaboque exhibit poor to moderate limnological conditions; Tibanica is in poor condition; Guaymaral has severely impaired to moderate conditions; and Juan Amarillo tends to present permanent severely impaired conditions, which indicates that it is the most polluted wetland. The index proposed was useful to classify the wetlands according to their limnological status, and it adequately represents the ecological quality of the Bogotá wetlands. RESUMEN Índice de diatomeas perifíticas para evaluar la calidad ecológica de humedales urbanos andinos de Bogotá, Colombia Se muestrearon cinco humedales de Bogotá (Guaymaral, Jaboque, Juan Amarillo, Santa María del Lago y Tibanica) y un humedal rural (Meridor, municipio de Tenjo) cuatro veces durante los periodos climáticos seco, lluvioso y de transición (entre 2007 y 2008). Se midieron las variables fisicoquímicas y se obtuvieron muestras de perifiton para evaluar la comunidad de diatomeas. Se establecieron valores de contaminación para cada especie de diatomeas y se calculó un índice de estado limnológico para valorar la calidad ecológica de los humedales. De acuerdo con el estado limnológico establecido, los seis humedales se pueden clasificar de la siguiente manera: Santa María del Lago, Meridor y Jaboque presentan condiciones limnológicas pobres a moderadas; Tibanica están en condiciones pobres; Guaymaral tiene condiciones malas a moderadas; y Juan Amarillo tiende a presentar malas condiciones permanentemente, lo que indica que es el humedal más contaminado. El índice propuesto fue útil para clasificar los humedales dentro de diferentes condiciones limnológicas y representa adecuadamente la calidad ecológica de los humedales de Bogotá. Palabras clave: Bioindicadores, índice de contaminación, humedales impactados, Andes de Colombia, Bacillariophyceae.

Diatoms are microscopic, unicellular, eukaryotic algae belonging to the Class Bacillariophyceae which are abundant in most aquatic habitats and serve as useful proxies for multi-dimensional analysis of ecosystems. They inhabit waters and... more

Diatoms are microscopic, unicellular, eukaryotic algae belonging to the Class Bacillariophyceae which are abundant in most aquatic habitats and serve as useful proxies for multi-dimensional analysis of ecosystems. They inhabit waters and soils of both saline and freshwater areas. Diatoms as primary producers are vital for life on Earth, serve as significant source of oxygen, have major impact on global carbon cycle and are food source for many organisms at other trophic levels. Moreover, diatoms provide an exceptional tool for examining environmental changes. Data on diatom abundance and diversity, both living and fossil are found to be very useful in environmental studies, since they are extremely sensitive to and respond rapidly to environmental changes with specific species being adapted to a particular environment. Most importantly, after death their silica frustules sink to the bottom, get added to the sedimentary records and preserve well within most sediments as diatomaceous earth. Diatom analysis has been undertaken across all continents to reconstruct past environments and a lot of attention goes out to develop techniques of modeling recent climate variability. Such diatom assemblages preserved at variable depths in sedimentary sequences have proven to be excellent proxies for inferring climate change events, catastrophic events and other stochastic variability of the environment. The diatom assemblages are also interpreted in combination with geochemistry and sedimentary characteristics for complete reconstructions of past environments and logical modeling for future trends. The present paper is a review of the available publications that have added to the significance of diatom assemblages in soil as palaeo-ecological indicators.

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... more

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

"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... more

"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."

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... more

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.

Glacier shrinkage and melting of snow patches caused by the current phase of warming is having a profound impact on lake ecosystems located in glacierized environments at high altitude and/or latitude because it alters the hydrology and... more

Glacier shrinkage and melting of snow patches caused by the current phase of warming is having a profound impact on lake ecosystems located in glacierized environments at high altitude and/or latitude because it alters the hydrology and the physico-chemistry of the river discharges and catchment runoff. These changes, in turn, have a major impact on the biota of these lakes. In this study, we combined geochemical and diatom analyses of a sediment core retrieved from Lake Kanas (N.W.
China) to assess how climate change has affected this
ecosystem over the past * 100 years. Our results
show that the aquatic ecosystem of Lake Kanas was
sensitive to changes in the regional climate over that
period of time. The lake has been affected by change in
hydrology (e.g. influx of glacier meltwater, variations
in precipitation) and change in hydrodynamics (water
column stability). The variations in abundance and
composition of the diatom assemblages observed in
the sedimentary record have been subtle and are
complex to interpret. The principal changes in the
diatom community were: (1) a rise in diatom accumulation rates starting in the AD 1970s that is coeval
with changes observed in temperate lakes of the
Northern Hemisphere and (2) an increase in species
diversity and assemblage turnover and a faster rate-of change since * AD 2000. The diatom community is
expected to change further with the projected melting
of the Kanas glacier throughout the twenty-first
century.