Two new marine species of Cocconeis (Bacillariophyceae) from the west coast of Sweden

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

Source identification and distribution reveals the potential of the geochemical Antarctic sea ice proxy IPSO25

The presence of a di-unsaturated highly branched isoprenoid (HBI) lipid biomarker (diene II) in Southern Ocean sediments has previously been proposed as a proxy measure of palaeo Antarctic sea ice. Here we show that a source of diene II is the sympagic diatom Berkeleya adeliensis Medlin. Furthermore, the propensity for B. adeliensis to flourish in platelet ice is reflected by an offshore downward gradient in diene II concentration in >100 surface sediments from Antarctic coastal and near-coastal environments. Since platelet ice formation is strongly associated with super-cooled freshwater inflow, we further hypothesize that sedimentary diene II provides a potentially sensitive proxy indicator of landfast sea ice influenced by meltwater discharge from nearby glaciers and ice shelves, and re-examination of some previous diene II downcore records supports this hypothesis. The term IPSO25-Ice Proxy for the Southern Ocean with 25 carbon atoms-is proposed as a proxy name for diene II

Spring phytoplankton onset after the ice break-up and sea-ice signature (Adélie Land, East Antarctica)

The phytoplankton onset following the spring ice break-up in Adélie Land, East Antarctica, was studied along a short transect, from 400 m off the continent to 5 km offshore, during the austral summer of 2002. Eight days after the ice break-up, some large colonial and solitary diatom cells, known to be associated with land-fast ice and present in downward fluxes, were unable to adapt in ice-free waters, while some other solitary and short-colony forming taxa (e.g., Fragilariopsis curta, F. cylindrus) did develop. Pelagic species were becoming more abundant offshore, replacing the typical sympagic (ice-associated) taxa. Archaeomonad cysts, usually associated with sea ice, were recorded in the surface waters nearshore. Rough weather restricted the data set, but we were able to confirm that some microalgae may be reliable sea-ice indicators and that seeding by sea ice only concerns a few taxa in this coastal area of East Antarctica. Keywords: Ice break-up; phytoplankton; sea-ice signature; East Antarctica (Published: 10 January 2011) Citation: Polar Research 2011, 30, 5910, doi: 10.3402/polar.v30i0.591

Estimation of some genetic parameters in potato. Consequences for selection.

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Fig. 1 in Two new marine species of Cocconeis (Bacillariophyceae) from the west coast of Sweden

Fig. 1. Map of the west coast of Sweden and location of sampling site, Vrångö Island (black circle)

A study of the diatom-dominated microplankton summer assemblages in coastal waters from Terre Adélie to the Mertz Glacier, East Antarctica (139°E–145°E)

In January 2004 the microplankton community from the coastal waters of Terre Adélie and Georges V Land (139°E - 145°E) was studied. Results showed a diatom-dominated bloom with chlorophyll a levels averaging 0.64 µg.l-1 at 5m depth (range 0.21 - 1.57 µg.l-1). Three geographic assemblages of diatoms were identified, based on principal diatom taxa abundances. The stratified waters near the Mertz Glacier presented highest phytoplankton biomasses (0.28 - 1.57 µg Chl a.l-1 at 5m) and diatom abundances (6 507 - 70 274 cells.l-1 at 5m), but low diversity, dominated by Fragilariopsis spp. Lower biomasses (0.38 – 0.94 µg Chl a.l-1 at 5m) and abundances (394 – 9 058 cells.l-1 at 5m) were observed in the mixed waters around the Astrolabe Glacier with a diverse diatom community characterised by larger species Corethron pennatum and Rhizosolenia spp. Finally an intermediate zone between them over the shallower shelf waters of the Adélie Bank represented by Chaetoceros criophilus, where biomasses (0.21 - 0.35 µg Chl a.l-1 at 5m) and abundances (1 190 - 5 431 cells.l-1 at 5m) were lowest, coinciding with the presence of abundant herbivorous zooplankton.Pelagant, contract EV/12/30

Biodiversity of carapace epibiont diatoms in loggerhead sea turtles (Caretta caretta Linnaeus 1758) in the Aegean Sea Turkish coast.

BACKGROUND: The Aegean Sea coast of Turkey hosts one of the most important nesting grounds for loggerhead sea turtles (Caretta caretta) in the Mediterranean Sea. Previous studies have revealed that the sea turtle carapace provides favourable conditions for various epibiontic organisms. Epibionts occurring on the carapace have been examined from different locations in the oceans. METHODS: This is the first time such a high number (39) of samples collected from nesting turtles during such a long time period (extending from 2011 to 2018) has been used for the study of the diatom component of the microbiome on the turtle carapaces. A total of 33 samples were investigated in terms of light microscopy (LM) and scanning electron microscopy (SEM). Six unprocessed biofilm fragments were subject to SEM observations. RESULTS: A total of 457 epizoic diatom taxa belonging to 86 genera were identified. Epizoic forms, e.g., Achnanthes spp., Chelonicola spp. or Tripterion spp. (also identified by SEM observations of the undisturbed pieces of the microbiome) dominated in terms of relative abundance, but the highest numbers of taxa were ubiquitously represented by Navicula (79), Nitzschia (45), Amphora (40), Cocconeis (32), Diploneis (25) and Mastogloia (23). Navicula perminuta and Delphineis australis were the most frequent taxa, present in 65% of the samples, both with an average relative abundance of 10%. The results of our study revealed that diatoms are an essential component of the loggerhead sea turtles' microbiome, in terms of high biodiversity and abundance. Although strict epibionts provide a signature of the turtle microbiome, the carapace as a solid substrate attracts numerous benthic diatom species which are considered opportunistic forms and can be found in the surrounding benthic habitats of the vast ocean littoral space

on Focused Ion Beam nanocuts

The marine diatom Olifantiella Riaux-Gobin et Compere predominantly occurs in tropical Indo-Pacific coral reef environments. The genus has about a dozen validly published taxa and is characterized by transapically elongate striae composed of a macroareola, broad perforated girdle, and tubular buciniportula process of trumpet-shape. The valve mantle of taxa related to the generitype, O. mascarenica, have a canal- shaped structure around the valve at the face / mantle junction, while those to O. gorandiana have a simple mantle or strongly narrow canal and complex buciniportula composed of hollow processes. The geographic distribution of Olifantiella is expanded in this study to include species observed in loggerhead sea turtles scrapes from the Aegean Turkish coast and samples from the Turkish Black Sea and Adriatic Sea coasts. Olifantiella has also been identified in Martinique Island, Caribbean Sea. A transfer of Navicula infirmitata is proposed due to the areola and buciniportula structure, as Olifantiella infirmitata. Further, an application of the Focused Ion Beam (FIB) to a sequential cutting of frustules allows resolution of Olifantiella mascarenica valve ultrastructure