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Catherine Riaux-gobin - One of the best experts on this subject based on the ideXlab platform.

  • Two new marine species of Cocconeis (Bacillariophyceae) from the west coast of Sweden
    European Journal of Taxonomy, 2019
    Co-Authors: Adil Al-handal, Catherine Riaux-gobin, Regine Jahn, Angela Katarina Wulff, Alison Minerovic
    Abstract:

    This paper is part of a project of studying benthic diatom biodiversity on marine coastal regions of Sweden with focus on rare and less known species. Two new species of Cocconeis Ehrenb. are described from Vrångö, a small island in the west coast of Sweden. Both species were found as epiphytic on the green alga Ulva intestinalis L. Cocconeis magnoareolata Al-Handal, Riaux-Gob., R.Jahn & A.K.Wulff sp. nov. is a small species not exceeding 9 µm in length and characterized by having large subquadrangular areolae on the sternum valve. Cocconeis vrangoensis Al-Handal & Riaux-Gob. sp. nov. appears similar to some taxa of the ‘Cocconeis scutellum complex’, but differs by its stria density on both valves and variable features of the areola and valvocopula ultrastructure. Detailed descriptions based on light and electron microscopy examination, a comparison with closely related taxa, as well as a description of the habitat of both species are here presented.

  • Planothidium juandenovense sp. nov. (Bacillariophyta) from Juan de Nova (Scattered Islands, Mozambique Channel) and other tropical environments: A new addition to the Planothidium delicatulum complex
    Fottea, 2018
    Co-Authors: Catherine Riaux-gobin, Andrzej Witkowski, Adil Al-handal, Anton Igersheim, Christopher S. Lobban, Pierre Compère
    Abstract:

    Planothidium juandenovense sp. nov. (Bacillariophyta) is described from the marine tropical environments of Juan de Nova I. (Mozambique Channel), Rodrigues I. (Mascarene Archipelago) and from Guam (Northern Mariana Is., Pacific). This small and relatively rare taxon has short multiseriate striae on the sternum valve (SV), hooked raphe valve (RV) terminal raphe endings and no SV cavum or hoof-shaped area. This taxon has similarities with Planothidium delicatulum (Kutz.) Round et Bukht. and Planothidium septentrionale (Ostrup) Round et Bukht. ex Rumrich et al., but also differences: e.g. a relatively narrow and rhombic SV sternum, void of areolae, with vestigial radiate structures and an uninterrupted marginal SV elevated crest or 'crista marginalis'. P. juandenovense sp. nov. is compared to some other Achnanthales with short SV striae. Cocconeis quarnerensis var. lanceolata Jurilj and Planothidium quarnerense f. rhombica (Giffen) comb. nov. may be close to our new taxon.

  • Cocconeis molesta Kütz., C. diaphana W.Sm. and C. dirupta W.Greg. (Bacillariophyta): type material, ambiguities and possible synonymies
    European Journal of Taxonomy, 2016
    Co-Authors: Catherine Riaux-gobin, Pierre Compère, Richard W. Jordan, Michel Coste, Jovita C. Yesilyurt
    Abstract:

    F.T. Kützing introduced Cocconeis molesta with only an uninformative description and a poor illustration: C. molesta has small, oblong valves and is an epiphyte. Another species, Cocconeis diaphana, described by William Smith, is said to have larger valves than C. molesta, with frustules that are relatively oblong. Smith described two forms: one with a distinct fascia on its raphe valve (var. β), the other without this feature. A third species, Cocconeis dirupta was described by Gregory, who expressed doubts that it differed from C. diaphana. Finally, Cocconeis molesta var. crucifera Grunow was first introduced in Van Heurck's Atlas but was subsequently treated by Van Heurck as a synonym of C. molesta. No previous account has examined the type material of these species. In this paper, we undertake that task and examine type slides and raw material in order to discriminate these different taxa. We conclude by recognizing three species: Cocconeis molesta Kütz., C. diaphana W.Sm. and C. dirupta W.Greg. Cocconeis diaphana var. β is considered to be a synonym of C. dirupta and C. molesta var. crucifera is considered to be a synonym of C. molesta. Lectotypes are designated for C. diaphana and C. dirupta.

  • Cocconeis Ehrenberg taxa (Bacillariophyta) with a marginal row of simple processes: relationship with the valvocopula system and distinctive features of related taxa
    Fottea, 2015
    Co-Authors: Catherine Riaux-gobin, Andrzej Witkowski, Pierre Compère, Oscar E Romero
    Abstract:

    As first observed on a group of taxa related to Cocconeis peltoides Hustedt, several other Cocconeis Ehrenberg (Bacillariophyta) taxa possess a row of minute marginal pores on the external side of their sternum valve (SV) connected to small and simple internal portules, or processes. These processes are often located in continuity with the striae, but can also be slightly shifted or distant from the distal areola of the striae. The row of pores is often, but not always, externally separated from the stria by a crista marginalis. Within Cocconeis, and possibly all raphid diatoms, these processes seem unique and restricted to a few taxa. A list is presented of the taxa pertaining (or close) to Cocconeis that are actually known to share these micro-structures. In addition, the morphological variability of the processes is described in detail and a morphological comparison of the taxa is provided. The characteristic features of taxa showing a row of SV processes permit the tentative definition of several morphological groups. It is difficult to prove the taxonomic affiliation of these taxa and demonstrate or refute that these processes are ancestral characters. Some of these taxa are rare and restricted to low latitudes (e.g., tropical taxa) while others are frequent and ubiquitous.

  • Achnanthes citronella, A. trachyderma comb. nov. (Bacillariophyta) and allied taxa pertaining to the same morphological group
    Phytotaxa, 2015
    Co-Authors: Catherine Riaux-gobin, Pierre Compère, Friedel Hinz, Luc Ector
    Abstract:

    Several diatoms in the family Achnanthaceae (Bacillariophyta), mainly from marine environments, have species with strongly apiculate, lemon-shaped valves. Some of them originally described under the genus Cocconeis ( i . e ., C . trachyderma or C . citronella ), while others were first described as Stauroneis species [ i . e . Stauroneis apiculata or S .(?) obesa ]. Afterwards, Cocconeis citronella has been recombined within Achnanthes by Hustedt. The type material of C . citronella from Albert Mann’s collection, housed in the Smithsonian Institution (US), has been examined with light microscope; some ambiguities are pointed out and new details added to the original description. The intricate history of the latter taxon is redrawn and comparison with allied taxa are tentatively addressed. Cocconeis trachyderma is lectotypified and recombined as Achnanthes trachyderma comb . nov . Stauroneis apiculata and S .(?) obesa are recombined as Achnanthes apiculata comb . nov . and Achnanthes obesa comb . nov . respectively. The examination with light and scanning electron microscope of several marine samples from the Society Archipelago details the unique morphology of Achnanthes trachyderma which, until recently, has been often misidentified as Achnanthes citronella due to certain similarities between both taxa.

Pierre Compère - One of the best experts on this subject based on the ideXlab platform.

  • Planothidium juandenovense sp. nov. (Bacillariophyta) from Juan de Nova (Scattered Islands, Mozambique Channel) and other tropical environments: A new addition to the Planothidium delicatulum complex
    Fottea, 2018
    Co-Authors: Catherine Riaux-gobin, Andrzej Witkowski, Adil Al-handal, Anton Igersheim, Christopher S. Lobban, Pierre Compère
    Abstract:

    Planothidium juandenovense sp. nov. (Bacillariophyta) is described from the marine tropical environments of Juan de Nova I. (Mozambique Channel), Rodrigues I. (Mascarene Archipelago) and from Guam (Northern Mariana Is., Pacific). This small and relatively rare taxon has short multiseriate striae on the sternum valve (SV), hooked raphe valve (RV) terminal raphe endings and no SV cavum or hoof-shaped area. This taxon has similarities with Planothidium delicatulum (Kutz.) Round et Bukht. and Planothidium septentrionale (Ostrup) Round et Bukht. ex Rumrich et al., but also differences: e.g. a relatively narrow and rhombic SV sternum, void of areolae, with vestigial radiate structures and an uninterrupted marginal SV elevated crest or 'crista marginalis'. P. juandenovense sp. nov. is compared to some other Achnanthales with short SV striae. Cocconeis quarnerensis var. lanceolata Jurilj and Planothidium quarnerense f. rhombica (Giffen) comb. nov. may be close to our new taxon.

  • Cocconeis molesta Kütz., C. diaphana W.Sm. and C. dirupta W.Greg. (Bacillariophyta): type material, ambiguities and possible synonymies
    European Journal of Taxonomy, 2016
    Co-Authors: Catherine Riaux-gobin, Pierre Compère, Richard W. Jordan, Michel Coste, Jovita C. Yesilyurt
    Abstract:

    F.T. Kützing introduced Cocconeis molesta with only an uninformative description and a poor illustration: C. molesta has small, oblong valves and is an epiphyte. Another species, Cocconeis diaphana, described by William Smith, is said to have larger valves than C. molesta, with frustules that are relatively oblong. Smith described two forms: one with a distinct fascia on its raphe valve (var. β), the other without this feature. A third species, Cocconeis dirupta was described by Gregory, who expressed doubts that it differed from C. diaphana. Finally, Cocconeis molesta var. crucifera Grunow was first introduced in Van Heurck's Atlas but was subsequently treated by Van Heurck as a synonym of C. molesta. No previous account has examined the type material of these species. In this paper, we undertake that task and examine type slides and raw material in order to discriminate these different taxa. We conclude by recognizing three species: Cocconeis molesta Kütz., C. diaphana W.Sm. and C. dirupta W.Greg. Cocconeis diaphana var. β is considered to be a synonym of C. dirupta and C. molesta var. crucifera is considered to be a synonym of C. molesta. Lectotypes are designated for C. diaphana and C. dirupta.

  • Cocconeis Ehrenberg taxa (Bacillariophyta) with a marginal row of simple processes: relationship with the valvocopula system and distinctive features of related taxa
    Fottea, 2015
    Co-Authors: Catherine Riaux-gobin, Andrzej Witkowski, Pierre Compère, Oscar E Romero
    Abstract:

    As first observed on a group of taxa related to Cocconeis peltoides Hustedt, several other Cocconeis Ehrenberg (Bacillariophyta) taxa possess a row of minute marginal pores on the external side of their sternum valve (SV) connected to small and simple internal portules, or processes. These processes are often located in continuity with the striae, but can also be slightly shifted or distant from the distal areola of the striae. The row of pores is often, but not always, externally separated from the stria by a crista marginalis. Within Cocconeis, and possibly all raphid diatoms, these processes seem unique and restricted to a few taxa. A list is presented of the taxa pertaining (or close) to Cocconeis that are actually known to share these micro-structures. In addition, the morphological variability of the processes is described in detail and a morphological comparison of the taxa is provided. The characteristic features of taxa showing a row of SV processes permit the tentative definition of several morphological groups. It is difficult to prove the taxonomic affiliation of these taxa and demonstrate or refute that these processes are ancestral characters. Some of these taxa are rare and restricted to low latitudes (e.g., tropical taxa) while others are frequent and ubiquitous.

  • Achnanthes citronella, A. trachyderma comb. nov. (Bacillariophyta) and allied taxa pertaining to the same morphological group
    Phytotaxa, 2015
    Co-Authors: Catherine Riaux-gobin, Pierre Compère, Friedel Hinz, Luc Ector
    Abstract:

    Several diatoms in the family Achnanthaceae (Bacillariophyta), mainly from marine environments, have species with strongly apiculate, lemon-shaped valves. Some of them originally described under the genus Cocconeis ( i . e ., C . trachyderma or C . citronella ), while others were first described as Stauroneis species [ i . e . Stauroneis apiculata or S .(?) obesa ]. Afterwards, Cocconeis citronella has been recombined within Achnanthes by Hustedt. The type material of C . citronella from Albert Mann’s collection, housed in the Smithsonian Institution (US), has been examined with light microscope; some ambiguities are pointed out and new details added to the original description. The intricate history of the latter taxon is redrawn and comparison with allied taxa are tentatively addressed. Cocconeis trachyderma is lectotypified and recombined as Achnanthes trachyderma comb . nov . Stauroneis apiculata and S .(?) obesa are recombined as Achnanthes apiculata comb . nov . and Achnanthes obesa comb . nov . respectively. The examination with light and scanning electron microscope of several marine samples from the Society Archipelago details the unique morphology of Achnanthes trachyderma which, until recently, has been often misidentified as Achnanthes citronella due to certain similarities between both taxa.

  • Cocconeis pinnata w gregory ex greville bacillariophyta lectotypification and an emended description after examination of type material and south pacific specimens
    Phytotaxa, 2014
    Co-Authors: Catherine Riauxgobin, Pierre Compère, Oscar E Romero, David M Williams
    Abstract:

    A marine species of Cocconeis (Bacillariophyta) from coral reef lagoon of Tahiti Island (Society Archipelago, South Pacific) was identified as Cocconeis pinnata W. Gregory ex Greville. Neither drawings nor micrographs of the raphe valve (RV) of C. pinnata are available in the literature. The examination of Gregory's type material (several slides annotated 'Arran 57' from Greville's collection housed in BM, British Museum, London, U.K.) allowed us to complete and emend the C. pinnata description. Lectotypification of C. pinnata is proposed. Since the raw material used by Gregory was not found, no scanning electron microscope (SEM) observation of type material can be provided. Except for Hustedt (1933) and a few later reports, all descriptions and illustrations agree with the original description. LM and SEM observations demonstrate that the sternum valve (SV) stria arrangement of specimens from Tahiti match those of the type. The description of the RV by Grunow in Van Heurck (1880) refers to a stria pattern very similar to that of C. pseudomarginata W. Gregory. The RV of C. pinnata, as revealed in LM and SEM, has a dense striation and no internal marginal rim. Both valves of C. pinnata have areolae with remarkable arborescent volae, which is a new feature for Cocconeis. Cocconeis pinnata is cosmopolitan, from cold-temperate to tropical areas. Several taxa have been formerly assigned to C. pinnata, though they are probably varieties of C. costata.

Oscar E Romero - One of the best experts on this subject based on the ideXlab platform.

  • Cocconeis Ehrenberg taxa (Bacillariophyta) with a marginal row of simple processes: relationship with the valvocopula system and distinctive features of related taxa
    Fottea, 2015
    Co-Authors: Catherine Riaux-gobin, Andrzej Witkowski, Pierre Compère, Oscar E Romero
    Abstract:

    As first observed on a group of taxa related to Cocconeis peltoides Hustedt, several other Cocconeis Ehrenberg (Bacillariophyta) taxa possess a row of minute marginal pores on the external side of their sternum valve (SV) connected to small and simple internal portules, or processes. These processes are often located in continuity with the striae, but can also be slightly shifted or distant from the distal areola of the striae. The row of pores is often, but not always, externally separated from the stria by a crista marginalis. Within Cocconeis, and possibly all raphid diatoms, these processes seem unique and restricted to a few taxa. A list is presented of the taxa pertaining (or close) to Cocconeis that are actually known to share these micro-structures. In addition, the morphological variability of the processes is described in detail and a morphological comparison of the taxa is provided. The characteristic features of taxa showing a row of SV processes permit the tentative definition of several morphological groups. It is difficult to prove the taxonomic affiliation of these taxa and demonstrate or refute that these processes are ancestral characters. Some of these taxa are rare and restricted to low latitudes (e.g., tropical taxa) while others are frequent and ubiquitous.

  • Cocconeis pinnata w gregory ex greville bacillariophyta lectotypification and an emended description after examination of type material and south pacific specimens
    Phytotaxa, 2014
    Co-Authors: Catherine Riauxgobin, Pierre Compère, Oscar E Romero, David M Williams
    Abstract:

    A marine species of Cocconeis (Bacillariophyta) from coral reef lagoon of Tahiti Island (Society Archipelago, South Pacific) was identified as Cocconeis pinnata W. Gregory ex Greville. Neither drawings nor micrographs of the raphe valve (RV) of C. pinnata are available in the literature. The examination of Gregory's type material (several slides annotated 'Arran 57' from Greville's collection housed in BM, British Museum, London, U.K.) allowed us to complete and emend the C. pinnata description. Lectotypification of C. pinnata is proposed. Since the raw material used by Gregory was not found, no scanning electron microscope (SEM) observation of type material can be provided. Except for Hustedt (1933) and a few later reports, all descriptions and illustrations agree with the original description. LM and SEM observations demonstrate that the sternum valve (SV) stria arrangement of specimens from Tahiti match those of the type. The description of the RV by Grunow in Van Heurck (1880) refers to a stria pattern very similar to that of C. pseudomarginata W. Gregory. The RV of C. pinnata, as revealed in LM and SEM, has a dense striation and no internal marginal rim. Both valves of C. pinnata have areolae with remarkable arborescent volae, which is a new feature for Cocconeis. Cocconeis pinnata is cosmopolitan, from cold-temperate to tropical areas. Several taxa have been formerly assigned to C. pinnata, though they are probably varieties of C. costata.

  • typification of Cocconeis lineata and Cocconeis euglypta bacillariophyta
    Diatom Research, 2013
    Co-Authors: Oscar E Romero, Regine Jahn
    Abstract:

    The nominate varieties of the monoraphid diatoms Cocconeis lineata Ehrenberg and C. euglypta Ehrenberg are typified. Lectotypes of both taxa are preserved at the Ehrenberg Collection, Museum fur Naturkunde, Berlin, Germany. The lectotype of C. lineata is a poorly detailed drawing, showing an ovoid valve (or frustule?) with two to three apical lines on each hemivalve. The lectotype of C. euglypta, contained in a mica, shows a unique, broadly elliptical sternum valve with up to five apical striae on each hemivalve, displaying a zigzag pattern. This is roughly consistent with the current concept of C. lineata and C. euglypta and with their usage over the last 160 years. To ensure stabilization of the names and current concepts for these two taxa, culture-based epitypes of C. lineata and C. euglypta are designated. Light and electron microscopy observations, as well as morphometric data from clones for both taxa, are presented and an amended description for each taxon is provided.

  • Cocconeis pediculus ehrenberg and c placentula ehrenberg var placentula bacillariophyta typification and taxonomy
    Fottea, 2009
    Co-Authors: Regine Jahn, Wolfhenning Kusber, Oscar E Romero
    Abstract:

    The nominate varieties of the monoraphid diatoms Cocconeis pediculus EHRENBERG and C. placentula EHRENBERG are typified. Discrepancies from common concepts in Ehrenberg's types, habitats and descriptions were discovered which might affect our current understanding of both Cocconeis species. To ensure stabilization of names and concepts for these two taxa, epitypes from a location in Berlin close to the locus typicus are presented. Monoclonal cultures of these two taxa have been established. Morphological and morphometric data from clones as well as from populations for both taxa are presented. The taxonomy of C. pediculus and C. placentula var. placentula is discussed and evaluated in the context of historical and recent publications.

Andrzej Witkowski - One of the best experts on this subject based on the ideXlab platform.

  • Epilithic diatom communities from areas of invasive Caulerpa species (Caulerpa taxifolia and Caulerpa cylindracea) in the Adriatic Sea, NE Mediterranean
    Mediterranean Marine Science, 2019
    Co-Authors: Andrzej Witkowski, Nenad Jasprica, Stijepo Ljubimir, Marijeta Čalić, Sławomir Dobosz, Iris Dupčić Radić, Enis Hrustić
    Abstract:

    Epilithic diatom community structures are compared among three locations of the eastern Adriatic Sea coast (Croatia), in the presence of two different invasive Caulerpa species, C. taxifolia and C. cylindracea, which have spread rapidly in the Mediterranean in the last decades. Forty samples were taken seasonally at three sites (island of Hvar, island of Mljet, and Dubrovnik) between November 2008 and October 2010. Light and electron microscopy examinations were used for qualitative analysis. Altogether 310 epilithic taxa belonging to 65 genera were identified. The highest number of these taxa belonged to Mastogloia (48) and Amphora (32), followed by Diploneis (24), Nitzschia (23), Navicula (22), and Cocconeis (19). A similar seasonal shift in growth form structure was observed for epilithic communities at the three sampling sites, where the number of erect group diatoms doubled (Hvar, Mljet) and tripled (Dubrovnik) in spring. Apart from erect forms, Dubrovnik and Mljet were characterised by adnate forms, while Hvar was characterised by tube-dwelling forms. The highest values of the Shannon-Wiener Diversity Index were recorded in autumn and ranged from 5.26 to 5.34. ANOSIM tests performed on species relative abundance data confirmed that the diatom communities differed significantly between the sampling sites, and that the differences were correlated with the presence of the two species of invasive macroalgae (Hvar – area of C. taxifolia ; Mljet and Dubrovnik – areas of C. cylindracea ). As revealed by SIMPER analyses, the group of taxa contributing the most to variance between diatom assemblages from sites of different invasive alga included Cocconeis scutellum var. scutellum , Rhopalodia pacifica , Navicula ramosissima , and Berkeleya rutilans . Although the spatial variation in communities may also reflect the effects of unmeasured environmental variables, the results suggest the possible influence of invasive seaweeds of the genus Caulerpa which may affect the habitat by competing with autochthonous algae. This study contributes to the knowledge of diatom diversity both at regional and at broader scales in these challenged environments.

  • Planothidium juandenovense sp. nov. (Bacillariophyta) from Juan de Nova (Scattered Islands, Mozambique Channel) and other tropical environments: A new addition to the Planothidium delicatulum complex
    Fottea, 2018
    Co-Authors: Catherine Riaux-gobin, Andrzej Witkowski, Adil Al-handal, Anton Igersheim, Christopher S. Lobban, Pierre Compère
    Abstract:

    Planothidium juandenovense sp. nov. (Bacillariophyta) is described from the marine tropical environments of Juan de Nova I. (Mozambique Channel), Rodrigues I. (Mascarene Archipelago) and from Guam (Northern Mariana Is., Pacific). This small and relatively rare taxon has short multiseriate striae on the sternum valve (SV), hooked raphe valve (RV) terminal raphe endings and no SV cavum or hoof-shaped area. This taxon has similarities with Planothidium delicatulum (Kutz.) Round et Bukht. and Planothidium septentrionale (Ostrup) Round et Bukht. ex Rumrich et al., but also differences: e.g. a relatively narrow and rhombic SV sternum, void of areolae, with vestigial radiate structures and an uninterrupted marginal SV elevated crest or 'crista marginalis'. P. juandenovense sp. nov. is compared to some other Achnanthales with short SV striae. Cocconeis quarnerensis var. lanceolata Jurilj and Planothidium quarnerense f. rhombica (Giffen) comb. nov. may be close to our new taxon.

  • sexual reproduction in schizostauron bacillariophyta and a preliminary phylogeny of the genus
    Phycologia, 2017
    Co-Authors: David G. Mann, Andrzej Witkowski, Nickolai A Davidovich, Olga I Davidovich, Przemyslaw Dabek, Izabela Zglobicka, K J Kurzydlowski, Evgeniy Gusev, Ewa Gorecka
    Abstract:

    Abstract: The focus of this paper is the sexual reproduction and phylogeny of Schizostauron Grunow, which were studied using clonal cultures isolated from the Indian Ocean coast of Mozambique near Tofo and Bazaruto. Taxa of Schizostauron were characterized by light and electron microscopy and a phylogeny derived from three genes (rbcL, psbC and short subunit). Schizostauron was established in the second half of the 19th century, then forgotten, with its taxa included in Cocconeis or Achnanthes sensu lato. Schizostauron, together with Astartiella and perhaps also Kolbesia and Karayevia, seems to form a third lineage of monoraphid diatoms, which are related to biraphid diatoms belonging to the Stauroneidaceae and Parlibellus, but not to the two other lineages of monoraphids (Achnanthes and the Achnanthidiaceae–Cocconeidaceae group). In culture, size reduction was followed by release of gametes and auxosporulation in mixtures of clones. Despite some morphological differences, four clones from the Bazaruto po...

  • Cocconeis Ehrenberg taxa (Bacillariophyta) with a marginal row of simple processes: relationship with the valvocopula system and distinctive features of related taxa
    Fottea, 2015
    Co-Authors: Catherine Riaux-gobin, Andrzej Witkowski, Pierre Compère, Oscar E Romero
    Abstract:

    As first observed on a group of taxa related to Cocconeis peltoides Hustedt, several other Cocconeis Ehrenberg (Bacillariophyta) taxa possess a row of minute marginal pores on the external side of their sternum valve (SV) connected to small and simple internal portules, or processes. These processes are often located in continuity with the striae, but can also be slightly shifted or distant from the distal areola of the striae. The row of pores is often, but not always, externally separated from the stria by a crista marginalis. Within Cocconeis, and possibly all raphid diatoms, these processes seem unique and restricted to a few taxa. A list is presented of the taxa pertaining (or close) to Cocconeis that are actually known to share these micro-structures. In addition, the morphological variability of the processes is described in detail and a morphological comparison of the taxa is provided. The characteristic features of taxa showing a row of SV processes permit the tentative definition of several morphological groups. It is difficult to prove the taxonomic affiliation of these taxa and demonstrate or refute that these processes are ancestral characters. Some of these taxa are rare and restricted to low latitudes (e.g., tropical taxa) while others are frequent and ubiquitous.

  • PALAEOENVIRONMENTAL CHANGES IN THE AREA OF THE SZCZECIN LAGOON (THE SOUTH WESTERN BALTIC SEA) AS RECORDED FROM DIATOMS
    2015
    Co-Authors: Andrzej Witkowski, Ryszard K. Borówka, Patrycja Gregorowicz, Andrzej Osadczuk, Joanna Œwiêta, Monika Lutyñska, Brygida Wawrzyniak-wydrowska, Robert Woziñski
    Abstract:

    Analyses of diatom assemblages were performed in sediment cores from the Szczecin Lagoon area, as a part of a multi-disciplinary research including seismoacoustic profiling and different types of palaeoecological and geological analy-ses: palynological, macrofossil, malacological, lithological, geochemical and sedimentological. Changes in the composition of a large spectrum of species of the local fauna and flora allowed the reconstruction of environmental conditions during the Late Glacial and Holocene in the Szczecin Lagoon. Succession of the diatom communities is the main topic of the present paper. In the Late Glacial sediments, the diatom flora was scarce and occurred only in core 42/99. In other cores, diatom assemblages characteristic for three phases of the Holocene development (limnic-swampy, marine/brackish-water and lagoonary) of the Szczecin Lagoon were distinguished. The Late Glacial (Older-Dryas (?), Allerød and Younger Dryas) record is incomplete and the flora is predominantly represented by Actinocy-clus normanii, Aulacoseira spp, Cocconeis placentula, and Fragilaria brevistriata. The oldest Holocene sediments of the limnic-swampy type, are characterised by freshwater and halophilous diatoms (e.g. Fragilaria brevistriata, Coc-coneis placentula and Stephanodiscus hantzschii). In the overlying marine sediments, only occasionally brackish-water taxa (e.g. Planothidium delicatulum, Cocconeis hauniensis) were observed. In the uppermost deposits formed in lagoonary conditions freshwater, halophilous and brackish-water species dominated (e.g. Aulacoseira granulata

Geoffrey Swain - One of the best experts on this subject based on the ideXlab platform.

  • Biofilm community structure and the associated drag penalties of a groomed fouling release ship hull coating
    2018
    Co-Authors: Kelli Z. Hunsucker, Gary J. Vora, Travis J. Hunsucker, Harrison Gardner, Dagmar H. Leary, Seongwon Kim, Baochuan Lin, Geoffrey Swain
    Abstract:

    Grooming is a proactive method to keep a ship’s hull free of fouling. This approach uses a frequent and gentle wiping of the hull surface to prevent the recruitment of fouling organisms. A study was designed to compare the community composition and the drag associated with biofilms formed on a groomed and ungroomed fouling release coating. The groomed biofilms were dominated by members of the Gammaproteobacteria and Alphaproteobacteria as well the diatoms Navicula, Gomphonemopsis, Cocconeis, and Amphora. Ungroomed biofilms were characterized by Phyllobacteriaceae, Xenococcaceae, Rhodobacteraceae, and the pennate diatoms Cyclophora, Cocconeis, and Amphora. The drag forces associated with a groomed biofilm (0.75 ± 0.09 N) were significantly less than the ungroomed biofilm (1.09 ± 0.06 N). Knowledge gained from this study has helped the design of additional testing which will improve grooming tool design, minimizing the growth of biofilms and thus lowering the frictional drag forces associated with groomed surfaces.

  • Diatom community structure on commercially available ship hull coatings
    Biofouling, 2011
    Co-Authors: Kelli A. Zargiel, Jeffrey S. Coogan, Geoffrey Swain
    Abstract:

    Diatoms are primary colonizers of both antifouling and fouling-release ship hull coatings. There are few published studies which report on diatom community development on modern ship hull coatings. This study reports diatom communities on eight commercial marine ship hull coatings exposed at three static immersion sites along the east coast of Florida, viz. Daytona, Sebastian, and Miami. The coatings tested were three ablative copper systems (Ameron ABC-3, International BRA-640, and Hempel Olympic 76600), two copper-free biocidal systems (E-Paint SN-1, Sherwin Williams HMF), and three fouling-release (FR) systems (International Intersleek 700, International Intersleek 900, and Hempel Hempasil). One hundred and twenty-seven species comprising 44 genera were identified, including some of the more commonly known foulers, viz. Achnanthes, Amphora, Cocconeis, Entomoneis, Licmophora, Melosira, Navicula, Nitzschia, Synedra, and Toxarium. A significant difference was seen among sites, with the more estuarine site...