scholarly journals The structure and diversity of freshwater diatom assemblages from Franz Josef Land Archipelago: a northern outpost for freshwater diatoms

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1705 ◽  
Author(s):  
Sergi Pla-Rabés ◽  
Paul B. Hamilton ◽  
Enric Ballesteros ◽  
Maria Gavrilo ◽  
Alan M. Friedlander ◽  
...  
Keyword(s):  
Seasonal Changes ◽  
Ph Gradient ◽  
Diatom Assemblages ◽  
Diatom Flora ◽  
Human Footprint ◽  
Franz Josef Land ◽  
Freshwater Diatoms ◽  
Arctic Conditions ◽  
Cell Densities ◽  
Freshwater Diatom

We examined diatom assemblages from 18 stream and pond samples in the Franz Josef Land Archipelago (FJL), the most northern land of Eurasia. More than 216 taxa were observed, revealing a rich circumpolar diatom flora, including many undescribed taxa. Widely distributed taxa were the most abundant by cell densities, while circumpolar taxa were the most species rich. Stream and pond habitats hosted different assemblages, and varied along a pH gradient.Diatoma tenuiswas the most abundant and ubiquitous taxon. However, several circumpolar taxa such asChamaepinnularia gandrupii, Cymbella botellus, Psammothidiumsp. andHumidophila laevissimawere also found in relatively high abundances. Aerophilic taxa were an important component of FJL diatom assemblages (Humidophilaspp.,Caloneisspp. andPinnulariaspp.), reflecting the large and extreme seasonal changes in Arctic conditions. We predict a decrease in the abundance of circumpolar taxa, an increase in local (α-) freshwater diatom diversity, but a decrease in regional diversity (circumpolar homogenization) as a result of current warming trends and to a lesser extent the increasing human footprint in the region.

scholarly journals Diatom diversity and distribution in Madeira Island streams (Portugal)

2020 ◽  
Vol 8 ◽  
Author(s):  
Catarina Ritter ◽  
Pedro Raposeiro ◽  
Vítor Gonçalves
Keyword(s):  
New Records ◽  
Distribution Patterns ◽  
Diatom Species ◽  
Diatom Assemblages ◽  
Field Campaign ◽  
Madeira Island ◽  
Madeira Archipelago ◽  
Freshwater Diatoms ◽  
Freshwater Diatom

Here, we present the data obtained from the samples collected in a field campaign during the spring of 2015 which aims for a better understanding of the diversity and distribution patterns of freshwater diatoms in Madeira Island. Following European and Portuguese standards and recommendations for routine diatom sampling and analysis, we collected samples in 40 sites, distributed in 27 permanent streams and identified the diatom species present, using general diatom floras and studies in Portuguese freshwater diatoms. Little is known about the diversity and distribution of freshwater diatom assemblages from Madeira Archipelago. This study reports a survey in 40 sites in Madeira Island distributed in 27 permanent streams. A total of 965 diatom (Bacillariophyta) occurrences were recorded, belonging to 130 different taxa from 44 genera and 27 families. The families with the highest number of occurrences were Bacillariaceae (176), Achnanthidiaceae (135) and Naviculaceae (133). The two diatom endemisms, described previously in Madeira Island (Lange-Bertalot 1993), Nitzschia macaronesica Lange-Bertalot and Navicula madeirensis Lange-Bertalot, were only observed in a small number of sites, located mostly at Laurissilva forest. Sixty species are new records, not only to Madeira Island, but also to the Madeira Archipelago.

Observations on new and rare species of freshwater diatoms from Cape Cod, Massachusetts, USA

2005 ◽  
Vol 83 (4) ◽  
pp. 362-378 ◽  
Author(s):  
Peter A Siver ◽  
Paul B Hamilton
Keyword(s):  
New Species ◽  
Rare Species ◽  
Surface Sediments ◽  
Cape Cod ◽  
Similar Species ◽  
New Combinations ◽  
Diatom Flora ◽  
Freshwater Diatoms ◽  
Scanning Electron ◽  
Freshwater Diatom

The freshwater diatom flora of Cape Cod, Massachusetts, USA, was recently described using surface sediments from 56 largely glacial kettle lakes scattered over the narrow peninsula. During our examination we had the opportunity to study seven rare and interesting taxa with light (LM) and scanning electron microscopy (SEM). Two of these organisms, Neidium statuarium Hamilton & Siver sp.nov. and Stenopterobia pseudodelicatissima Siver & Hamilton sp.nov., are described as new species. Two new combinations, along with emended descriptions based on SEM, are provided for Nupela vitiosa (Schimanski) Siver & Hamilton comb.nov. and Tryblionella scalaris (Ehrenberg) Siver & Hamilton comb.nov. Morphological details of three additional and rare species, Neidium fasiatum Østrup, Neidium sp., and Tryblionella plana var. fennica (Hustedt) Simola are also provided. The relationships of each taxon to other similar species are discussed.Key words: Cape Cod, Neidium, new species, Nupela, Stenopterobia, Tryblionella.

Holocene diatom assemblages from Dunderbukhta sediments, West Svalbard

2019 ◽  
pp. 242-245
Author(s):  
Ksenya V. Poleshchuk ◽  
Zinaida V. Pushina ◽  
Sergey R. Verkulich
Keyword(s):  
Environmental Changes ◽  
Ecological Groups ◽  
Diatom Assemblages ◽  
Diatom Analysis ◽  
Diatom Flora ◽  
Sediment Samples ◽  
Ecological Zones ◽  
Middle Holocene ◽  
Temperature Trends

The diatom analysis results of sediment samples from Dunderbukta area (Wedel Jarlsberg Land, West Svalbard) are presented in this paper. The diatom flora consists of four ecological groups, which ratio indicates three ecological zones. These zones show environmental changes of the area in early–middle Holocene that is demonstrating periods of regression and temperature trends.

Encyonema oblonga (Bacillariophyta, Cymbellaceae), a new species from Shanxi Province, China

Phytotaxa ◽  
2021 ◽  
Vol 480 (3) ◽  
pp. 284-290
Author(s):  
QI LIU ◽  
JIAJIA LI ◽  
QUANXI WANG ◽  
JOHN PATRICK KOCIOLEK Patrick Kociolek ◽  
Shulian Xie
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
New Species ◽  
Shanxi Province ◽  
Diatom Flora ◽  
A New Species ◽  
Scanning Electron ◽  
Freshwater Diatom

A new species, Encyonema oblonga Liu & Xie, is collected during a survey of the freshwater diatom flora of Manghe River, Shanxi, China. The valves of this new species are oblong with rounded apices and have the features typical of Encyonema, including complex areolae. We compare the new species with the most similar taxa, E. leei, E. leei var. sinensis and E. appalachianum and consider that  E. leei var. sinensis is the valid name.  The morphology of E. oblonga is documented with light and scanning electron microscopy.

scholarly journals Distrionella coxiana, a new fragilarioid diatom species (Bacillariophyceae) from Tierra del Fuego, Patagonia, Argentina

2019 ◽  
Vol 152 (2) ◽  
pp. 385-391
Author(s):  
Valeria Casa ◽  
Gabriela Mataloni ◽  
Bart Van de Vijver
Keyword(s):  
Typical Feature ◽  
Morphological Features ◽  
Tierra Del Fuego ◽  
New Taxon ◽  
Diatom Species ◽  
Unique Combination ◽  
Diatom Flora ◽  
Electron Microscopical ◽  
Scanning Electron ◽  
Freshwater Diatom

Background and aims – A few years ago, a new survey started of the freshwater diatom flora from peatbogs of Tierra del Fuego (southern Argentina). During this survey, an unknown fragilarioid diatom belonging to the genus Distrionella that could not be identified using the currently available literature was discovered. Methods – Using both Light Microscopical and Scanning Electron Microscopical techniques, the morphology of the unknown Distrionella species has been analysed. The new taxon is properly described, illustrated and compared with all other possible similar Distrionella taxa, known worldwide. Key results – Distrionella coxiana possesses a unique combination of morphological features that excludes conspecificity with all other members of the genus; it is characterized in having narrow, linear valves with small, capitate apices. Transapical ribs, a typical feature of the genus Distrionella, are only weakly developed. One rimoportula is observed close to the apices. Both apices have well-developed apical porefields. The girdle bands bear one complete row of poroids often accompanied by a second, incomplete row of small poroids. Notes on the occurrence and ecology of the new taxon are added.

Habitat preferences in freshwater diatom communities from sub-Antarctic Îles Kerguelen

2001 ◽  
Vol 13 (1) ◽  
pp. 28-36 ◽  
Author(s):  
Bart Van De Vijver ◽  
Pieter Ledeganck ◽  
Louis Beyens
Keyword(s):  
Habitat Preferences ◽  
Habitat Type ◽  
Research Station ◽  
Running Waters ◽  
Diatom Flora ◽  
Limited Sampling ◽  
Sampling Campaign ◽  
Diatom Communities ◽  
Geographical Position ◽  
Freshwater Diatom

A limited sampling campaign on the main island of Îles Kerguelen revealed 170 freshwater diatom taxa, belonging to 29 genera. Four different communities were distinguished in two major groups, being determined principally by habitat type. The Fragilaria vaucheriae–Fragilaria germainii assemblage occurs exclusively in running waters. The three other communities, observed in standing waterbodies, are separated by their geographical position on the island with the Fragilaria exigua–Aulacoseira alpigena and the Fragilaria exigua–Fragilaria vaucheriae assemblages, mainly found in the Lac Studer area and the Fragilaria pinnata var. pinnata assemblage, recorded near the coastal line and the research station. Analysis of different waterbody types revealed the habitat preference of the various diatom taxa and identified a diatom flora for running waters and one preferring stagnant waterbodies.

Characteristic of marine Oligocene diatom flora from the Cenozoic key section of West Kamchatka

2019 ◽  
pp. 205-209
Author(s):  
Andrey Yu. Gladenkov
Keyword(s):  
Taxonomic Composition ◽  
Diatom Assemblages ◽  
Diatom Flora ◽  
Early Oligocene ◽  
Kamchatka Region

The results on study of fossil diatom flora from marine Cenozoic key section of West Kamchatka at the Kvachina Bay are given. Based on distinctions in taxonomic composition and stratigraphic occurrence of biochronologically important taxa in the section, diatom assemblages of different age dated from the early Oligocene to earliest Miocene are identified. In their entirety and paleontological characteristics studied Oligocene assemblages are the most representative among all assemblages of this age known from Kamchatka region.

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