scholarly journals An ex situ and in vitro approach to delineate pennate diatom species with bioindicator potentials in a well mixed tropical estuarine ecosystem

2016 ◽  
Vol 3 (6) ◽  
pp. 299-317
Author(s):  
Abhishek Mukherjee ◽  
Subhajit Das ◽  
Sabyasachi Chakraborty ◽  
Tarun Kumar De
Keyword(s):  
Coastal Upwelling ◽  
Ex Situ ◽  
Centric Diatom ◽  
Diatom Species ◽  
Estuarine Ecosystem ◽  
Pennate Diatom ◽  
Extrinsic Factors ◽  
Nutrient Pool ◽  
Hooghly Estuary ◽  
Pennate Diatoms

An experiment was performed on selected pennate diatom species collected from the well mixed waters of the Hooghly Estuary with the aim of distinguishing the ones with qualities to be employed as monitors of their ecosystem. The Hooghly Estuary is enriched with domestic, sewage and agricultural effluents and coastal upwelling along with tide-mediated advective circulation from the mangrove forests ensure concomitant nutrient pool replenishment in this ecoregion. There have been several attempts to establish certain centric diatom species as bioindicators in various parts of the world owing to their better responsiveness to sudden shifts in stoichiometry but hardly any with pennate diatoms. Pennate diatoms are typical benthic mat formers in the intertidal regions, on submerged surfaces and thus bear greater feasibility to be employed as accurate pointers to long term deviations in their respective ecosystems, in spite of the greater sensitivity of the centric diatoms. The study was carried out in laboratory controlled environment to minimize the interference from other extrinsic factors compromising the outcome and also due to the fact that such studies to be performed in natural conditions require a decent financial support and time to conclusively arrive upon the objectives. From the present endeavour it was inferred that Nitzschia sigmoidea, Pleurosigma angulatum and Ulnaria oxyrhyncus (formerly Synedra ulna var. oxyrhyncus) stood a good chance of being recruited as bioindicators to eutrophic well mixed estuaries, similar to the one they had been sampled from.

Structure and Composition of Ice Algal Assemblages from the Gulf of St. Lawrence, Magdalen Islands Area

1990 ◽  
Vol 47 (4) ◽  
pp. 780-788 ◽  
Author(s):  
Michèle A. De Sève ◽  
Maxwell J. Dunbar
Keyword(s):  
Dominant Species ◽  
Centric Diatom ◽  
Diatom Species ◽  
Centric Diatoms ◽  
Planktonic Diatom ◽  
Pack Ice ◽  
Landfast Ice ◽  
Algal Assemblages ◽  
Pennate Diatoms ◽  
Index Of Diversity

Two types of ice algal assemblages were found in the Gulf of St. Lawrence: assemblages composed predominantly of pennate diatoms (abundance > 98.0%) and assemblages with a high abundance of centric diatoms (abundance > 46.2%). The first type is similar to Arctic landfast ice algal assemblages with the pennate diatoms Nitzschia cylindrus, N. polaris, and Navicula kariana as dominant species. The second type is similar to drifting ice algal assemblages previously described from the Gulf of St. Lawrence, with a percentage of centric diatom species > 46.2% due to the dominance of the planktonic diatom Thalassiosira nordenskioeldii. Species richness and the Shannon-Weaver index of diversity were low; density ranged from 104–106 × cells∙L−1 and was negatively correlated with percent centric diatoms. Results on the structure and the composition of the ice algal assemblages are related to ice type, i.e. landfast and drifting pack ice, and compared with ice algal assemblages from higher latitudes.

New species of benthic marine diatoms (Bacillariophyta) from the Western Pacific islands of Guam and Yap

Phytotaxa ◽  
2021 ◽  
Vol 508 (3) ◽  
Author(s):  
CHRISTOPHER S. LOBBAN
Keyword(s):  
Pacific Islands ◽  
Central Area ◽  
Marshall Islands ◽  
Marine Diatom ◽  
Large Species ◽  
Diatom Species ◽  
Cell Interior ◽  
Pennate Diatom ◽  
The Western Pacific ◽  
Benthic Marine Diatoms

In the course of preparation of a major checklist for Yap and ongoing investigations into the benthic marine diatom flora of Micronesia, thirteen new araphid and raphid pennate diatom species have been recognized and are described here. Plagiogramma subatomus is even smaller than P. atomus and the pseudoseptum forms a box with only a small opening toward the cell interior. Licmophora romuli is similar in size and spathulate shape to L. remulus, but the majority of the striae in the lamina lack vimines. L. graphis is exceedingly delicate, pencil-shaped, with apical striae 60–70 in 10 µm. Divergita biformis and D. decipiens are straight species with striae biseriate on the margin, uniseriate on the valve face, differing in the shape and prominence of the sternum and the shape of the valve-face areolae. D. macinnisii (from Marshall Islands, but included here for comparison) is curved, again with the decussate areolar pattern on the mantle, but with single extended areolae along each side of the linear sternum. These characters slightly amend the diagnosis of the genus.  Thalassionema baculum is a very short member of the genus, linear and isopolar. Climaconeis tarangensis is curved and differs from C. riddleae in stria density and areola shape; C. minaegensis is straight, without a stauros or craticular bars, of intermediate length, 228–247 µm. First SEM observations of Climaconeis lorenzii are presented and an updated key to Climaconeis is appended. Parlibellus paschalis is a tube-dwelling species differing from P. delognei is lacking cuniculi and pores in the central area. P. waabensis is a relatively large species, possibly tube-dwelling, that differs from P. delognei in shape and spacing of central striae and from P. berkeleyi in width and stria density. Pleurosigma simulacrum differs in ultrastructural details from P. intermedium. Lastly, Nitzschia tarangensis is a conopeate species, spathulate in profile with ribs along the edge of the valve depression and bordering the raphe, and with pores in the peri-raphe zone.

scholarly journals Abiotic ammonification and gross ammonium photoproduction in the upwelling system off central Chile (36° S)

2012 ◽  
Vol 9 (12) ◽  
pp. 18479-18518
Author(s):  
A. Rain-Franco ◽  
C. Muñoz ◽  
C. Fernandez
Keyword(s):  
Organic Matter ◽  
Coastal Upwelling ◽  
Archaeal Community ◽  
Simultaneous Occurrence ◽  
Diatom Species ◽  
Chaetoceros Muelleri ◽  
Central Chile ◽  
Upwelling System ◽  
Simulated Solar Radiation ◽  
Radiation Conditions

Abstract. We investigated the production of ammonium via photodegradation of dissolved organic matter (DOM) in the coastal upwelling system off central Chile (36° S). Photoammonification experiments were carried out using exudates obtained from representative diatom species (Chaetoceros muelleri and Thalassiosira minuscule) and natural marine DOM under simulated solar radiation conditions. Additionally, we evaluated the use of photoproduced ammonium by natural microbial communities and separated ammonium oxidizing archaea and bacteria by using GC-7 as an inhibitor of the archaeal community. We found photoammonification operating at two levels: via the transformation of DOM by UV radiation (abiotic ammonification) and via the simultaneous occurrence of abiotic phototransformation and biological remineralization of DOM into NH4+ (referred as gross photoproduction of NH4+). The maximum rates of abiotic ammonification reached 0.057 μmol L−1 h−1, whereas maximum rates of gross photoproduction reached 0.746 μmol L−1 h−1. Our results also suggest that ammonium oxidizing archaea could dominate the biotic remineralization induced by photodegradation of organic matter and consequently play an important role in the local N cycle. Abiotic ammonium photoproduction in coastal upwelling systems could support between 7 and 50% of the spring-summer phytoplankton NH4+ demand. Surprisingly, gross ammonium photoproduction (remineralization induced by abiotic ammonification) might support 50 to 180% of spring-summer phytoplankton NH4+ assimilation.

scholarly journals NEW METHOD OF ESTIMATION OF THE RELATIVE AREA OF PERFORATIONS ON VALVES OF CENTRIC DIATOMS USING SEM IMAGES ON THE EXAMPLE OF MINIDISUS VODYANITSKIYI LYAKH ET BEDOSHVILI

2019 ◽  
Vol 21 ◽  
pp. 46-52
Author(s):  
Anton M. Lyakh ◽  
Yekaterina D. Bedoshvili ◽  
Olga V. Shikhat
Keyword(s):  
Land Plants ◽  
New Method ◽  
Centric Diatom ◽  
Relative Area ◽  
Diatom Species ◽  
Sem Images ◽  
Centric Diatoms ◽  
Diatom Valve ◽  
Small Valve ◽  
Valve Area

The diatoms interact with the environment through the siliceous frustule. The total area of frustule perforations determines the ability of diatom to exchange nutrients, gases and other matters. The aim of the present study was to estimate the area of perforations on the valve surface of a centric diatom. In the paper we describe a method for the estimation of the area of perforations on a diatom valve using SEM images. The method is tested on valves of centric diatom Minidiscus vodyanitskiyi Lyakh et Bedoshvili. The results show that the total area of cribral pores is less than 5% of the total valve area. This value is consistent with the relative perforation of land plants leaves, which is less than 3%. We hypothesize that such small valve area occupied by perforations is usual for many other centric diatom species. To verify this hypothesis additional researches are necessary.

scholarly journals Mating type specific transcriptomic response to sex inducing pheromone in the pennate diatom Seminavis robusta

2020 ◽  
Author(s):  
Gust Bilcke ◽  
Koen Van den Berge ◽  
Sam De Decker ◽  
Eli Bonneure ◽  
Nicole Poulsen ◽  
...  
Keyword(s):  
Sexual Reproduction ◽  
Mating Type ◽  
Target Genes ◽  
Specific Response ◽  
Pennate Diatom ◽  
Transcriptomic Response ◽  
Searching Behaviour ◽  
Cgmp Signaling ◽  
Phase Progression ◽  
Pennate Diatoms

AbstractSexual reproduction is a fundamental phase in the life cycle of most diatoms. Despite its role as a source of genetic variation, it is rarely reported in nature and its molecular foundations remain largely unknown. Here, we integrate independent transcriptomic datasets, in order to prioritize genes responding to sex inducing pheromones (SIPs) in the pennate diatom Seminavis robusta. We observe marked gene expression changes associated with SIP treatment in both mating types, including an inhibition of S-phase progression, chloroplast division, mitosis and cell wall formation. Meanwhile, meiotic genes are upregulated in response to SIP, including a sexually induced diatom specific cyclin (dsCyc). Our data further suggest an important role for reactive oxygen species, energy metabolism and cGMP signaling during the early stages of sexual reproduction. In addition, we identify several genes with a mating type specific response to SIP, and link their expression pattern with physiological responses such as the production of the attraction pheromone diproline and mate-searching behaviour in MT+. Combined, our results provide a model for early sexual reproduction in pennate diatoms and significantly expand the suite of target genes to detect sexual reproduction events in natural diatom populations.

scholarly journals Exploring Molecular Signs of Sex in the Marine Diatom Skeletonema marinoi

Genes ◽  
2019 ◽  
Vol 10 (7) ◽  
pp. 494 ◽  
Author(s):  
Ferrante ◽  
Entrambasaguas ◽  
Johansson ◽  
Töpel ◽  
Kremp ◽  
...  
Keyword(s):  
Sexual Reproduction ◽  
Reduction Process ◽  
Life Cycles ◽  
Marine Diatom ◽  
Centric Diatom ◽  
Rna Seq ◽  
Pennate Diatom ◽  
Planktonic Diatom ◽  
Expression Of Genes ◽  
Skeletonema Marinoi

Sexual reproduction plays a fundamental role in diatom life cycles. It contributes to increasing genetic diversity through meiotic recombination and also represents the phase where large-sized cells are produced to counteract the cell size reduction process that characterizes these microalgae. With the aim to identify genes linked to the sexual phase of the centric planktonic diatom Skeletonema marinoi, we carried out an RNA-seq experiment comparing the expression level of transcripts in sexualized cells with that of large cells not competent for sex. A set of genes involved in meiosis were found upregulated. Despite the fact that flagellate gametes were observed in the sample, we did not detect the expression of genes involved in the synthesis of flagella that were upregulated during sexual reproduction in another centric diatom. A comparison with the set of genes changing during the first phases of sexual reproduction of the pennate diatom Pseudo-nitzschia multistriata revealed the existence of commonalities, including the strong upregulation of genes with an unknown function that we named Sex Induced Genes (SIG). Our results further broadened the panel of genes that can be used as a marker for sexual reproduction of diatoms, crucial for the interpretation of metatranscriptomic datasets.

New records of centric diatoms from Yakutia (Bolshoe Toko Lake): SEM morphology, ecology and distribution

2018 ◽  
Vol 52 (2) ◽  
pp. 245-252 ◽  
Author(s):  
S. I. Genkal ◽  
V. A. Gabyshev
Keyword(s):  
Species Composition ◽  
River Basin ◽  
New Records ◽  
Water Bodies ◽  
Centric Diatom ◽  
Diatom Species ◽  
Centric Diatoms ◽  
Sem Study ◽  
First Time ◽  
Sem Morphology

As a result of a SEM study of phytoplankton, the first data on centric diatom species composition in Bolshoye Toko Lake, Yakutia, were obtained. Ten species (Aulacoseira — 5, Cyclotella — 1, Discostella — 1, Handmannia — 1, Pliocaenicus — 1) were found, and one taxon from the genus Pliocaenicus was identified to the genus level. Of these, nine taxa are reported for the first time in the water bodies of the Aldan River basin and Discostella guslyakovyi in Yakutia.

Sign in / Sign up

Export Citation Format

Share Document