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Ömer Lekesiz - One of the best experts on this subject based on the ideXlab platform.

  • Eco-assessment of West Mediterranean basin’s rivers (Turkey) using diatom metrics and multivariate approaches
    Environmental Science and Pollution Research, 2020
    Co-Authors: Abuzer Çelekli, Ömer Lekesiz
    Abstract:

    Bio-evaluating of surface waters is not a new approach but is becoming more important since the application of the European Water Framework Directive (WFD). The present study was designed to evaluate the limno-ecological conditions of rivers in the West Mediterranean basin of Turkey using diatom metrics and multivariate approaches according to the WFD requirements. Canonical correspondence analysis (CCA) was used to assess the relationships of diatom species and environmental variables from 17 stations of 12 rivers sampled in two seasons. The CCA indicated that nitrite, chloride, electrical conductivity (EC), sulfate, temperature, and total phosphorus (TP) are the most explanatory factors on the distribution of the diatom species. Karasu River had the most deteriorated ecosystem, distinctly revealed by the CCA. Nutrient enrichment and high EC, biological oxygen demand (BOD_5), and temperature values were noticed in this ecosystem. Karasu River was also characterized by pollution tolerant diatom species (e.g., Nitzschia inconspicua , Nitzschia pusilla , Halamphora normanii , and Rhoicosphenia abbreviata ). Trophic index Turkey (TIT), eutrophication and/or pollution index-diatom (EPI-D), and trophic index (TI) showed poor ecological conditions in Karasu and Hamzabey rivers when a moderate environment quality in Dalaman River (at R6 station) and a good ecological state in Kocadere River. A high ecological status was found in Dalaman (at R5 station) concerning the results of TIT and TI, while a good condition was recorded based on EPI-D. This ecosystem was also associated with pollution-sensitive diatom taxa ( Achnanthidium minutissimum , Cymbella excisa , Meridion circulare , and Gomphonema olivaceum ). Results of CCA were corroborated with the bio-assessment of sampling stations based on diatom metrics. TIT, TI, and EPI-D had different indices’ scores, but they showed significantly positive correlations with logTP. Spearman correlation coefficient value of TIT strengthens the suitability of it for the bio-assessment of the rivers in the West Mediterranean basin of Turkey.

  • Eco-assessment of West Mediterranean basin's rivers (Turkey) using diatom metrics and multivariate approaches.
    Environmental Science and Pollution Research, 2020
    Co-Authors: Abuzer Çelekli, Ömer Lekesiz
    Abstract:

    Bio-evaluating of surface waters is not a new approach but is becoming more important since the application of the European Water Framework Directive (WFD). The present study was designed to evaluate the limno-ecological conditions of rivers in the West Mediterranean basin of Turkey using diatom metrics and multivariate approaches according to the WFD requirements. Canonical correspondence analysis (CCA) was used to assess the relationships of diatom species and environmental variables from 17 stations of 12 rivers sampled in two seasons. The CCA indicated that nitrite, chloride, electrical conductivity (EC), sulfate, temperature, and total phosphorus (TP) are the most explanatory factors on the distribution of the diatom species. Karasu River had the most deteriorated ecosystem, distinctly revealed by the CCA. Nutrient enrichment and high EC, biological oxygen demand (BOD5), and temperature values were noticed in this ecosystem. Karasu River was also characterized by pollution tolerant diatom species (e.g., Nitzschia inconspicua, Nitzschia pusilla, Halamphora normanii, and Rhoicosphenia abbreviata). Trophic index Turkey (TIT), eutrophication and/or pollution index-diatom (EPI-D), and trophic index (TI) showed poor ecological conditions in Karasu and Hamzabey rivers when a moderate environment quality in Dalaman River (at R6 station) and a good ecological state in Kocadere River. A high ecological status was found in Dalaman (at R5 station) concerning the results of TIT and TI, while a good condition was recorded based on EPI-D. This ecosystem was also associated with pollution-sensitive diatom taxa (Achnanthidium minutissimum, Cymbella excisa, Meridion circulare, and Gomphonema olivaceum). Results of CCA were corroborated with the bio-assessment of sampling stations based on diatom metrics. TIT, TI, and EPI-D had different indices’ scores, but they showed significantly positive correlations with logTP. Spearman correlation coefficient value of TIT strengthens the suitability of it for the bio-assessment of the rivers in the West Mediterranean basin of Turkey.

Evan W. Thomas - One of the best experts on this subject based on the ideXlab platform.

  • Rhoicosphenia kloseri , a new isopolar Rhoicosphenia (Bacillariophyta) species from the Antarctic with comparison to other isopolar Rhoicosphenia
    Phytotaxa, 2016
    Co-Authors: Evan W. Thomas, Ryszard Ligowski
    Abstract:

    Rhoicosphenia is a common diatom in both freshwater and marine ecosystems and the genus can be found on nearly every continent. Despite the fact that the genus is common, few new species have been reported from outside of Europe, Asia, and North America, and only one species has been previously described from the Antarctic. Further, most Rhoicosphenia are heteropolar in valve outline, asymmetrical to the transapical axis, while few taxa are isopolar. During investigations into the epiphytes on the red alga Georgiella confluens from the South Shetland Islands, a new marine, isopolar Rhoicosphenia was discovered and is herein described and documented with both light and scanning electron microscopy. Rhoicosphenia kloseri is isopolar, and in that regard similar to other isopolar taxa, such as R . genuflexa and R . pullus , but does not fit the morphological species concept of those taxa and is thus described as new. This new species discovery is following a trend of high rates of discovery of previously ignored morphological diversity within the genus Rhoicosphenia .

  • Historical and Current Perspectives on the Systematics of the ‘Enigmatic’ Diatom Genus Rhoicosphenia (Bacillariophyta), with Single and Multi-Molecular Marker and Morphological Analyses and Discussion on the Monophyly of ‘Monoraphid’ Diatoms
    2016
    Co-Authors: Evan W. Thomas, Joshua G. Stepanek, Patrick J. Kociolek
    Abstract:

    This study seeks to determine the phylogenetic position of the diatom genus Rhoicosphenia. Currently, four hypotheses based on the morphology of the siliceous valve and its various ultrastructural components, sexual reproduction, and chloroplasts have been proposed. Two previous morphological studies have tentatively placed Rhoicosphenia near members of the Achnanthidiaceae and Gomphonemataceae, and no molecular studies have been completed. The position of Rhoicosphenia as sister to ‘monoraphid’ diatoms is problematic due to the apparent non-monophyly of that group, so hypotheses of ‘monoraphid’ monophyly are also tested. Using an analysis of morphological and cytological features, as well as sequences from three genes, SSU, LSU, and rbcL, recovered from several freshwater Rhoicosphenia populations that have similar morphology to Rhoicosphenia abbreviata (Agardh) Lange-Bertalot, we have analyzed the phylogenetic position of Rhoicosphenia in the context of raphid diatoms. Further, we have used topology testing to determine the statistical likelihoods of these relationships. The hypothesis that Rhoicosphenia is a member of the Achnanthidiaceae cannot be rejected, while the hypothesis that it is a member of the Gomphonemataceae can be rejected. In our analyses, members of the Achnanthidiaceae are basal to Rhoicosphenia, and Rhoicosphenia is basal to the Cymbellales, or a basal member of the Cymbellales, which includes the Gomphonemataceae. Hypothesis testing rejects the monophyly of ‘monoraphid’ diatoms.

  • Rhoicosphenia populations sequenced including name, ID, molecular marker sequences available, and GenBank accession numbers.
    2016
    Co-Authors: Evan W. Thomas, Joshua G. Stepanek, Patrick J. Kociolek
    Abstract:

    Rhoicosphenia populations sequenced including name, ID, molecular marker sequences available, and GenBank accession numbers.

  • Sampling location information Rhoicosphenia populations sequenced including species, ID, State, County, Site Name, Latitude, Longitude, Type, and Collection number.
    2016
    Co-Authors: Evan W. Thomas, Joshua G. Stepanek, Patrick J. Kociolek
    Abstract:

    Sampling location information Rhoicosphenia populations sequenced including species, ID, State, County, Site Name, Latitude, Longitude, Type, and Collection number.

  • transfer of Rhoicosphenia vanheurckii grunow to planothidium round bukhtiyarova
    Diatom Research, 2015
    Co-Authors: Evan W. Thomas, Bart Van De Vijver, Patrick J. Kociolek
    Abstract:

    Rhoicosphenia is a relatively small genus with about 30 species and 30 infraspecific varieties. Over the past decade there has been a renewed interest in describing previously undocumented diversity in Europe, Asia and North America, from fossil and extant material, and from marine and freshwater environments. Of the ca. 60 Rhoicosphenia taxa, one species, R. lesothensis, has already been transferred out of the genus. During a literature review of the genus, a passage by Hustedt suggesting the need to transfer another species, R. vanheurckii, out of the genus was examined. Our morphological investigations result in the transfer of R. vanheurckii to the genus Planothidium. Although this diatom does not bear the cavum or sinus typical of most Planothidium species, it fits with the other characters of the genus and will retain the specific epithet, as P. vanheurckii (Grunow) E.W. Thomas, Van de Vijver & Kociolek comb. nov.

Abuzer Çelekli - One of the best experts on this subject based on the ideXlab platform.

  • Eco-assessment of West Mediterranean basin’s rivers (Turkey) using diatom metrics and multivariate approaches
    Environmental Science and Pollution Research, 2020
    Co-Authors: Abuzer Çelekli, Ömer Lekesiz
    Abstract:

    Bio-evaluating of surface waters is not a new approach but is becoming more important since the application of the European Water Framework Directive (WFD). The present study was designed to evaluate the limno-ecological conditions of rivers in the West Mediterranean basin of Turkey using diatom metrics and multivariate approaches according to the WFD requirements. Canonical correspondence analysis (CCA) was used to assess the relationships of diatom species and environmental variables from 17 stations of 12 rivers sampled in two seasons. The CCA indicated that nitrite, chloride, electrical conductivity (EC), sulfate, temperature, and total phosphorus (TP) are the most explanatory factors on the distribution of the diatom species. Karasu River had the most deteriorated ecosystem, distinctly revealed by the CCA. Nutrient enrichment and high EC, biological oxygen demand (BOD_5), and temperature values were noticed in this ecosystem. Karasu River was also characterized by pollution tolerant diatom species (e.g., Nitzschia inconspicua , Nitzschia pusilla , Halamphora normanii , and Rhoicosphenia abbreviata ). Trophic index Turkey (TIT), eutrophication and/or pollution index-diatom (EPI-D), and trophic index (TI) showed poor ecological conditions in Karasu and Hamzabey rivers when a moderate environment quality in Dalaman River (at R6 station) and a good ecological state in Kocadere River. A high ecological status was found in Dalaman (at R5 station) concerning the results of TIT and TI, while a good condition was recorded based on EPI-D. This ecosystem was also associated with pollution-sensitive diatom taxa ( Achnanthidium minutissimum , Cymbella excisa , Meridion circulare , and Gomphonema olivaceum ). Results of CCA were corroborated with the bio-assessment of sampling stations based on diatom metrics. TIT, TI, and EPI-D had different indices’ scores, but they showed significantly positive correlations with logTP. Spearman correlation coefficient value of TIT strengthens the suitability of it for the bio-assessment of the rivers in the West Mediterranean basin of Turkey.

  • Eco-assessment of West Mediterranean basin's rivers (Turkey) using diatom metrics and multivariate approaches.
    Environmental Science and Pollution Research, 2020
    Co-Authors: Abuzer Çelekli, Ömer Lekesiz
    Abstract:

    Bio-evaluating of surface waters is not a new approach but is becoming more important since the application of the European Water Framework Directive (WFD). The present study was designed to evaluate the limno-ecological conditions of rivers in the West Mediterranean basin of Turkey using diatom metrics and multivariate approaches according to the WFD requirements. Canonical correspondence analysis (CCA) was used to assess the relationships of diatom species and environmental variables from 17 stations of 12 rivers sampled in two seasons. The CCA indicated that nitrite, chloride, electrical conductivity (EC), sulfate, temperature, and total phosphorus (TP) are the most explanatory factors on the distribution of the diatom species. Karasu River had the most deteriorated ecosystem, distinctly revealed by the CCA. Nutrient enrichment and high EC, biological oxygen demand (BOD5), and temperature values were noticed in this ecosystem. Karasu River was also characterized by pollution tolerant diatom species (e.g., Nitzschia inconspicua, Nitzschia pusilla, Halamphora normanii, and Rhoicosphenia abbreviata). Trophic index Turkey (TIT), eutrophication and/or pollution index-diatom (EPI-D), and trophic index (TI) showed poor ecological conditions in Karasu and Hamzabey rivers when a moderate environment quality in Dalaman River (at R6 station) and a good ecological state in Kocadere River. A high ecological status was found in Dalaman (at R5 station) concerning the results of TIT and TI, while a good condition was recorded based on EPI-D. This ecosystem was also associated with pollution-sensitive diatom taxa (Achnanthidium minutissimum, Cymbella excisa, Meridion circulare, and Gomphonema olivaceum). Results of CCA were corroborated with the bio-assessment of sampling stations based on diatom metrics. TIT, TI, and EPI-D had different indices’ scores, but they showed significantly positive correlations with logTP. Spearman correlation coefficient value of TIT strengthens the suitability of it for the bio-assessment of the rivers in the West Mediterranean basin of Turkey.

Patrick J. Kociolek - One of the best experts on this subject based on the ideXlab platform.

Holt, Jack R. - One of the best experts on this subject based on the ideXlab platform.

  • A Study of Diatom Communities of the Upper Main Stem of the Susquehanna River during Summer 2017
    Bucknell Digital Commons, 2017
    Co-Authors: Levesque Joshua, Wetzel Elise, Garity Maggie, Holt, Jack R.
    Abstract:

    The upper main stem of the Susquehanna River is formed by the confluence of the West and North Branch, both of which are chemically and physically distinctive. The upper main stem retains the signatures of the two branches due to weak lateral mixing, and we refer to them as the West Branch plume (WBP) and the North Branch plume (NBP). Thus, characterization of the diatom communities requires samples taken from sites that occur in the plumes of both branches. Since 2009, we have monitored the upper main stem at an established transect that straddles Byers Island near Shamokin Dam, PA and below the Adam T. Bower inflatable dam at Sunbury, PA. Attached diatom communities were sampled from stones which were prepared for examination by scanning electron microscopy. The Pollution Tolerance Index (PTI) and Shannon Diversity Index (SDI) values showed very little variation between all sites (2.38-3.03 and 2.35-2.93). We found the greatest species richness in the diatom communities of the NBP (Site 3- 30; Site 4- 29). Proportional Bray-Curtis Similarity analyses of samples showed low to moderate overlap between the diatom communities. Across all sites we identified 57 different species. Habitats of the NBP were dominated by Discostella pseudostelligera (a small centric), Rhoicosphenia abbreviata (a biraphid), and Achnanthidium minutissium (a small monoraphid). Similar habitats of the WBP were dominated by Ach. minutissium, Encyonema appalachianum (a biraphid). Despite similarities between 2014 and 2017 regarding discharge, the diatom communities were depauperate this year (57 taxa; 104.470 cfs) compared to other high discharge summers (June, July, and August) especially 2014 (93 taxa; 80,590 cfs). Difference in taxa richness could possibly be explained by lingering effects of a prior low discharge year (2016- 36,562 cfs)

  • A Study of the Diatom Communities in the Upper Main Stem of the Susquehanna River During an Unusually Wet Summer
    Bucknell Digital Commons, 2015
    Co-Authors: Alwali, Amir Younous, Holt, Jack R.
    Abstract:

    The upper main stem of the Susquehanna River is formed by the confluence of the West and North Branches, each of which is chemically and physically distinctive. The upper main stem retains the signatures of the two branches due to weak lateral mixing, and we refer to them as the North Branch plume (NBP) and West Branch plume (WBP). Thus, characterization of the diatom communities required samples taken from sites that occur in the plumes of both branches. Since 2009 when our river monitoring program began on the upper main stem, the summer of 2015 was an unusually wet year. Furthermore, monthly average discharge levels of the river during July exceeded those of any year during the 77 years of USGS records for the upper main stem. Indeed, the high water required that we reduce the scope of active sampling to one set of collections at each site together with artificial substrates. Our samples were taken from an established transect that straddles Byers Island near Shamokin Dam, PA and below the Adam T. Bower inflatable dam at Sunbury, PA. Diatom samples from diatometers, stones and other substrates were prepared for examination by electron microscopy. Within the plumes of the two branches, we focused on two particular habitats inhabited by diatom communities: stone, and diatometer. Overall, we identified approximately 93 different species in this study. Taxa richness in WBP (sites 1 and 5) was relatively low 16-24 and 19 species in the stone (16-24) and diatometer (19) communities, respectively. Similar communities from NBP (sites 2, 3 and 4) were richer and more diverse (e.g. 29-48 taxa on stones and 22-34 taxa on diatometers. Habitats of the NBP were dominated by a small centric and biraphid species (e.g. Discostella pseudostelligera and Rhoicosphenia abbreviata ) and similar habitats of the WBP were dominated by monoraphid species (e.g. Achnanthidium deflexum, Achananthidium minutissium, and Cocconeis placentula). Our preliminary results suggest that the high levels of discharge through the summer until we made our collections on July 27 contributed to differences in diatom communities between substrates