Diatoms in the Early Valdai (Weichselian) sediments in Lake Ladoga basin

2019 ◽  
pp. 225-228
Author(s):  
Anna V. Ludikova
Keyword(s):  
Species Diversity ◽  
High Energy ◽  
Lake Ladoga ◽  
Diatom Assemblages ◽  
Marine Diatoms ◽  
Selective Preservation

The pioneer diatom study of the Early Weichselian (Valdai) sediments in Lake Ladoga basin was performed. The specifics of the diatom assemblages (co-occurrence of ecologically incompatible taxa, poor species diversity, low diatom concentration and selective preservation) suggest that during the Early Weichselian time intense erosion of previously deposited marine Eemian (Mikulino) sediments prevailed, which resulted in re-deposition of marine diatoms. The sedimentation took place in high-energy environments unfavorable for diatom accumulation and preservation.

Ostracods as Tsunami Tracers in Holocene Sequences

2010 ◽  
Vol 73 (1) ◽  
pp. 130-135 ◽  
Author(s):  
Francisco Ruiz ◽  
Manuel Abad ◽  
Luís Miguel Cáceres ◽  
Joaquín Rodríguez Vidal ◽  
María Isabel Carretero ◽  
...  
Keyword(s):  
Population Structure ◽  
Species Diversity ◽  
Indian Ocean ◽  
High Energy ◽  
Indian Ocean Tsunami ◽  
Tsunami Deposits ◽  
Shallow Marine ◽  
Juvenile Stages ◽  
Marine Areas ◽  
Age Population Structure

This review analyses the ostracod record in Holocene tsunami deposits, using an overview of the 2004 Indian Ocean tsunami impact on its recent populations and the associated tsunamigenic deposits, together with results from numerous investigations of other Holocene sequences. Different features such as the variability of the local assemblages, population density, species diversity, age population structure (e.g., percentages of adults and juvenile stages) or taphonomical signatures suggest that these microorganisms may be included amongst the most promising tracers of these high-energy events in marshes, lakes, lagoons or shallow marine areas.

scholarly journals The diversity of diatom assemblages developed on fallow soil in Pogórska Wola near Tarnów (southern Poland)

2015 ◽  
Vol 68 (1) ◽  
pp. 33-42 ◽  
Author(s):  
Jadwiga Stanek-Tarkowska ◽  
Teresa Noga ◽  
Natalia Kochman-Kędziora ◽  
Łukasz Peszek ◽  
Anita Pajączek ◽  
...  
Keyword(s):  
Species Diversity ◽  
Dominant Species ◽  
Wiener Index ◽  
Elevated Concentration ◽  
Fallow Land ◽  
Loose Sand ◽  
Diatom Assemblages ◽  
Neutral Species ◽  
Southern Poland ◽  
Fallow Soil

The aim of this work was to investigate the species diversity of diatoms growing on fallow fields on loose sand. The study site was located in the western part of Pogórska Wola near Tarnów (southern Poland). Samples were collected from fallow land once a month from April to December 2011. 57 diatom taxa from 19 different genera were found. The most numerous genera were <em>Fragilaria</em> (8) and <em>Luticola</em> (7). The highest species richness was observed in December, November and July, while the highest values of species diversity (Shannon–Wiener index) were recorded between August and October. Four taxa – <em>Pinnularia borealis</em> Ehrenb. var. <em>borealis</em>, <em>Stauroneis borrichii</em> (Petersen) Lund, <em>Hantzschia amphioxys</em> (Ehrenb.) Grunow, and <em>Luticola nivalis</em> (Ehrenb.) D.G. Mann, were found to be the dominant species. Neutral species (a pH of about 7) dominated in all months (from April to December), reaching an over 90% share in the assemblage. In terms of nitrogen content, nitrogen-autotrophic taxa, tolerating an elevated concentration of organically bound nitrogen, occurred most abundantly, as was indicated by the low content of nitrogen in the soil.

Testing the accuracy of genus-level data to predict species diversity in Cenozoic marine diatoms

Geology ◽  
2016 ◽  
Vol 44 (12) ◽  
pp. 1051-1054 ◽  
Author(s):  
Robert Wiese ◽  
Johan Renaudie ◽  
David B. Lazarus
Keyword(s):  
Species Diversity ◽  
Marine Diatoms ◽  
Genus Level ◽  
Level Data

scholarly journals Long-Term Studies Of Surface-Sediment Diatom Assemblages In Assessing The Ecological State Of Lake Ladoga, The Largest European Lake

2021 ◽  
Vol 14 (1) ◽  
pp. 251-262
Author(s):  
Anna V. Ludikova
Keyword(s):  
Surface Sediment ◽  
Lake Ladoga ◽  
Anthropogenic Pressure ◽  
Ecological State ◽  
Diatom Assemblages ◽  
Ecosystem Recovery ◽  
Phytoplankton Communities ◽  
The 1960S ◽  
Ecosystem State

The study continues a series of observations started in the late 1950s, aimed at inferring changes in the Lake Ladoga ecosystem state recorded in the surface-sediment diatom assemblages. At the pre-anthropogenic stage (prior to the 1960s), the composition of the surface-sediment diatom assemblages indicated an oligotrophic state of Lake Ladoga. With the increased P load to the lake (late 1960s–1980s), the transition to a mesotrophic state was recorded via increased proportions of eutrophic species and decreased abundances of the taxa typical of the pre-anthropogenic stage. In the early 1990s, the composition of the surface-sediment diatom assemblages still indicated a mesotrophic state despite a decreased external P load. At the present de-eutrophication stage of Lake Ladoga (the 2000s), the abundances of eutrophic taxa steadily decrease while some taxa typical of the pre-anthropogenic period return to their dominating position in the surface-sediment diatom assemblages. However, despite the decreased P concentrations, the Lake Ladoga ecosystem has not returned to its pre-anthropogenic state as indicated by the present-day composition of the surface-sediment diatom assemblages. This suggests a delayed ecosystem response to the decreased anthropogenic pressure, and possibly some irreversible changes resulting from the eutrophication. At present, de-eutrophication processes and ecosystem recovery are superimposed upon the recent climatic changes that govern the onset and duration of the vegetative seasons for the phytoplankton communities in Lake Ladoga. The diatom-inferred changes in the ecological state of Lake Ladoga are in agreement with the results of longterm hydrochemical and hydrobiological studies.

scholarly journals Epilithic lichen cover in assessing the quality of the coastal water environment in Karelia

2021 ◽  
Vol 20 (1) ◽  
pp. 409-413
Author(s):  
A. V. Sonina
Keyword(s):  
Species Diversity ◽  
Coastal Water ◽  
Water Environment ◽  
The State ◽  
Lichen Species ◽  
Water Bodies ◽  
Phosphorus Compounds ◽  
Lake Ladoga ◽  
Lichen Cover

The paper summarizes the data obtained by analyzing the reaction of the coastal epilithic lichen cover tothe chemical parameters of water in reservoirs of different types and uses. The study was carried out on the shores of freshwater bodies (Lake Onega, Lake Ladoga, Lososinka, Suna rivers) with different anthropogenic pressures in the Republicof Karelia. At each place of study, the lichen cover was described at the survey sites (frame 10 x 20 cm) along the transectand water samples were taken for chemical analysis. The aim of the work is to identify indicators of the coastal epilithic lichen cover to indicate the quality of the aquatic environment and assess the state of coastal ecosystems. The lichen flora ofthe surveyed coasts of fresh water bodies has 53 species, the highest species diversity of lichens is characterized by placeswithout obvious sources of pollution – the Kivach reserve (29 species), the shores of Lake Ladoga (27 species) and the Botanical Garden of PetrSU (16 species), and in urban conditions ( Petrozavodsk), a large settlement (Yanishpole) and nearthe pulp and paper industry (Kondopoga), the number of lichen species is much lower (8, 5 and 4). Regression analysisshowed the dependence of the number of lichen species on the registration site on the concentration of phosphorus compounds in water (p < 0.05). A tendency to a decrease in species diversity and a decrease in the total coverage of lichens withan increase in nitrogenous compounds in water was noted. This made it possible to propose the epilithic lichen cover as anobject-indicator of the state of the coastal water environment under conditions of anthropogenic pollution of water bodies.

scholarly journals A First Estimate of Species Diversity for Benthic Diatom Assemblages from the Revillagigedo Archipelago, Mexico

Diversity ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 458
Author(s):  
David A. Siqueiros Beltrones ◽  
Francisco Omar López-Fuerte ◽  
Yuriko Jocselin Martínez ◽  
María del Carmen Altamirano-Cerecedo
Keyword(s):  
Species Diversity ◽  
Pacific Coast ◽  
New Records ◽  
Benthic Diatom ◽  
Marine Diatom ◽  
Diatom Assemblages ◽  
Species List ◽  
Mexican Pacific ◽  
Epiphytic Diatoms ◽  
Revillagigedo Archipelago

Recent investigations at previously unexplored localities on the Mexican coast have confirmed the high taxonomic potential of benthic marine diatom assemblages (BMDA) in the region. An exploratory study of epiphytic diatoms of macroalgae in the Revillagigedo Archipelago (RA) suggested that further studies would yield many more taxa, prompting the hypothesis that diversity measurements, based on ecological indices, would be among the highest in pristine environments. Thus, the aim of this research was to enrich the record of epiphytic diatom floristics of the RA, and to estimate species diversity based on information theory (H′). Floristically, 167 identified taxa are added here to the BMDA species list of the RA, bringing the total to 397 taxa overall, including 52 taxa that are potentially new records for the Mexican Pacific coast. Among the most conspicuous genera are Mastogloia with five new taxa and it remains the most diverse genus with 55 taxa overall, followed by Cocconeis (27), Nitzschia (24), Amphora (23), Navicula (19), Diploneis (17) and Grammatophora (15). As expected for a pristine environment, the computed species diversity values for the BMDA were high, ranging from H′ = 3.92–5.2, depicting stability. Future surveys are expected to further increase the species richness of BMDA for the RA.

The E-ring: interactions with plasma and implications for its evolution

1984 ◽  
Vol 75 ◽  
pp. 599-602
Author(s):  
T.V. Johnson ◽  
G.E. Morfill ◽  
E. Grun
Keyword(s):  
Time Scale ◽  
Particle Density ◽  
High Energy ◽  
Particle Removal ◽  
Density Region ◽  
Drag Forces ◽  
Orbit Evolution ◽  
History Of ◽  
Ring Particle ◽  
Ring Material

A number of lines of evidence suggest that the particles making up the E-ring are small, on the order of a few microns or less in size (Terrile and Tokunaga, 1980, BAAS; Pang et al., 1982 Saturn meeting; Tucson, AZ). This suggests that a variety of electromagnetic and plasma affects may be important in considering the history of such particles. We have shown (Morfill et al., 1982, J. Geophys. Res., in press) that plasma drags forces from the corotating plasma will rapidly evolve E-ring particle orbits to increasing distance from Saturn until a point is reached where radiation drag forces acting to decrease orbital radius balance this outward acceleration. This occurs at approximately Rhea's orbit, although the exact value is subject to many uncertainties. The time scale for plasma drag to move particles from Enceladus' orbit to the outer E-ring is ~104yr. A variety of effects also act to remove particles, primarily sputtering by both high energy charged particles (Cheng et al., 1982, J. Geophys. Res., in press) and corotating plasma (Morfill et al., 1982). The time scale for sputtering away one micron particles is also short, 102 - 10 yrs. Thus the detailed particle density profile in the E-ring is set by a competition between orbit evolution and particle removal. The high density region near Enceladus' orbit may result from the sputtering yeild of corotating ions being less than unity at this radius (e.g. Eviatar et al., 1982, Saturn meeting). In any case, an active source of E-ring material is required if the feature is not very ephemeral - Enceladus itself, with its geologically recent surface, appears still to be the best candidate for the ultimate source of E-ring material.

Analysis of electron-diffraction intensity profiles using a photodiode-array detection system

1983 ◽  
Vol 41 ◽  
pp. 322-323
Author(s):  
J. B. Warren
Keyword(s):  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Detection System ◽  
High Energy ◽  
Photographic Emulsion ◽  
Diffraction Intensity ◽  
Silicon Photodiode ◽  
Photodiode Array Detection ◽  
Analog To Digital ◽  
Photodiode Array

Electron diffraction intensity profiles have been used extensively in studies of polycrystalline and amorphous thin films. In previous work, diffraction intensity profiles were quantitized either by mechanically scanning the photographic emulsion with a densitometer or by using deflection coils to scan the diffraction pattern over a stationary detector. Such methods tend to be slow, and the intensities must still be converted from analog to digital form for quantitative analysis. The Instrumentation Division at Brookhaven has designed and constructed a electron diffractometer, based on a silicon photodiode array, that overcomes these disadvantages. The instrument is compact (Fig. 1), can be used with any unmodified electron microscope, and acquires the data in a form immediately accessible by microcomputer.Major components include a RETICON 1024 element photodiode array for the de tector, an Analog Devices MAS-1202 analog digital converter and a Digital Equipment LSI 11/2 microcomputer. The photodiode array cannot detect high energy electrons without damage so an f/1.4 lens is used to focus the phosphor screen image of the diffraction pattern on to the photodiode array.

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