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.

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.

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.

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.

scholarly journals Variation of Diatoms and Silicon in a Tributary of the Three Gorges Reservoir: Evidence of Interaction

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1369 ◽  
Author(s):  
Wei Xiao ◽  
Yubo Huang ◽  
Wujuan Mi ◽  
Hongyan Wu ◽  
Yonghong Bi
Keyword(s):  
Species Composition ◽  
Cell Density ◽  
Three Gorges Reservoir ◽  
Water Discharge ◽  
Three Gorges ◽  
Diatom Species ◽  
The Three Gorges Reservoir ◽  
The Three Gorges ◽  
Centric Diatoms ◽  
Pennate Diatoms

To gain insight into the variation of diatoms and silicon and their interaction in a tributary of the Three Gorges Reservoir (TGR), the Xiangxi River was chosen as a representative tributary, and dissolved silicon (DSi) and biogenic silicon (BSi) were investigated monthly from February 2015 to December 2016, accompanied by diatom species composition and cell density analyses. The results showed that the diatom population and its relationship with silicon concentration were significantly different between the lacustrine zone and riverine zone (P < 0.05). The cell density in the lacustrine zone (6.20 × 105 ~ 9.97 × 107 cells/L) was significantly higher than that in the riverine zone (7.90 × 104 ~ 1.81 × 107 cells/L) (P < 0.01). Water velocity was a key factor in determining the diatom species composition. Centric diatoms were the dominant species in the lacustrine zone, and pennate diatoms were the primary species in the riverine zone, which indicated that centric diatoms outcompete pennate diatoms under the influence of the TGR’s operation. BSi showed a significant linear relationship with the cell density. DSi had a significant negative relationship with the cell density in the lacustrine zone, while no significant relationship was found in the riverine zone. This meant that the main contributor to BSi was diatoms, but DSi was primarily affected by water discharge, not diatom uptake. It could be deduced that the spatiotemporal heterogeneity of diatom communities was influenced by the TGR’s operation. Silicon cycling in the tributary was significantly affected by diatoms, and the current concentration of DSi was sufficient for diatom growth and showed no significant effects on the diatom community.

Some centric diatoms (Bacillariophyta) from Neogene deposits of the Fisher Massif (Prince Charles Mountains, East Antarctica)

2011 ◽  
Vol 45 ◽  
pp. 32-49
Author(s):  
R. M. Gogorev ◽  
Z. V. Pushina
Keyword(s):  
Marine Sediments ◽  
East Antarctica ◽  
Benthic Diatoms ◽  
Detailed Data ◽  
Planktonic Algae ◽  
Centric Diatoms ◽  
Planktonic Diatom ◽  
Oceanic Species ◽  
Diatom Complexes

The richest diatom complexes have revealed due to the study of glacial-marine sediments sampled in the Fisher Massif (Prince Charles Mountains, East Antarctica) during 52nd and 53rd Russian Antarctic Expeditions (Polar Marine Geol. Survey Expedition) in 2006/07 and 2007/08. Three diatom complexes are distinguished according to different palaeoecological conditions: the planktonic one is located in the basis of the outcrop, while mixed planktonic-benthic and benthic ones being located above. The planktonic diatom complexes are dominated by two oceanic species Actinocyclus ingens (up to 8%) and Denticulopsis simonseni (up to 80%). There are 15 planktonic algae, e. g. Eucampia аntarctica, Fragilariopsis spp., Rhizosolenia spp., Rouxia antarctica, Podosira antarctica sp. nov., Stellarima microtrias; and also unknown and non-described benthic diatoms Achnanthes sp., Cocconeis spp., Rhabdonema (s. l.) spp. and Synedra (s. l.) spp. Detailed data on morphology and taxonomy of 10 centric diatoms are presented, including 3 newly described species.

scholarly journals Ecological assessment using diatom community in Avarga Toson Lake (Mongolia)

2021 ◽  
Vol 20 (1) ◽  
pp. 526-530
Author(s):  
Ts. Bukhchuluun
Keyword(s):  
Species Composition ◽  
Human Activities ◽  
Dominant Species ◽  
Sediment Accumulation ◽  
Ecological Assessment ◽  
Livestock Grazing ◽  
Diatom Species ◽  
Diatom Community ◽  
Diatom Communities ◽  
High Sediment

A total of 32 diatom species were recorded in Avarga Toson Lake. Motile diatom species are dominatingin diatom communities. The species composition of two coexisted lakes is markedly different. Diatom richness, speciescomposition, and dominant species indicate that Burd lake is polluted by livestock grazing or domestic pollution, andToson Lake is polluted by human activities with high sediment accumulation at the bottom.

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