Identification of Freshwater Diatoms from Live Material. Eileen J. Cox

1997 ◽  
Vol 16 (1) ◽  
pp. 299-300 ◽  
Author(s):  
Bruce C. Parker
Keyword(s):  
Freshwater Diatoms

Annual Cycle of Freshwater Diatoms in the High Arctic Revealed by Multiparameter Fluorescent Staining

2020 ◽  
Vol 80 (3) ◽  
pp. 559-572
Author(s):  
Eva Hejduková ◽  
Josef Elster ◽  
Linda Nedbalová
Keyword(s):  
Annual Cycle ◽  
High Arctic ◽  
Fluorescent Staining ◽  
Freshwater Diatoms

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 Freshwater Diatoms as Indicators of Combined Long-Term Mining and Urban Stressors in Junction Creek (Ontario, Canada)

Environments ◽  
2018 ◽  
Vol 5 (2) ◽  
pp. 30 ◽  
Author(s):  
Isabelle Lavoie ◽  
Soizic Morin ◽  
Vincent Laderriere ◽  
Claude Fortin
Keyword(s):  
Freshwater Diatoms

Eunotia spp. (Bacillariophyceae) from Middle Eocene lake sediments and comments on the origin of the diatom raphe

2007 ◽  
Vol 85 (1) ◽  
pp. 83-90 ◽  
Author(s):  
Peter A. Siver ◽  
Alexander P. Wolfe
Keyword(s):  
Lake Sediments ◽  
Northwest Territories ◽  
Middle Eocene ◽  
Valve Morphology ◽  
Progressive Degeneration ◽  
Extant Species ◽  
Freshwater Diatoms ◽  
Molecular Phylogenetic

Freshwater diatoms belonging to the genus Eunotia Ehrenberg 1837 are well preserved in Middle Eocene lake sediments from the Northwest Territories, Canada. Although two distinct valve morphologies are recognized, both have features that are entirely compatible with modern congeneric taxa, including dorsiventral valve morphology, striae spanning the valve face and extending onto the mantle, raphe structures on the mantle that extend distally onto the valve face, two helictoglossae per valve, and one apical rimoportula per valve. These findings establish that the genus Eunotia, and likely freshwater raphid diatoms as a whole, are more ancient than previously believed, dating back to at least 40 Ma. One of the observed morphotypes has a raphe spanning more than 80% of the valve length as well as a narrow hyaline area extending between proximal raphe endings and interrupting mantle striae. These features imply that the raphe system among certain ancient representatives of Eunotia was more developed relative to modern counterparts. The notion of progressive degeneration of the raphe within Eunotia is supported by several extant species. Collectively, these observations confirm molecular phylogenetic arguments that position Eunotia as a basal raphid diatom.

Taxonomy, phylogeny, and paleoecology of Eoseira wilsonii gen. et sp. nov., a Middle Eocene diatom (Bacillariophyceae: Aulacoseiraceae) from lake sediments at Horsefly, British Columbia, Canada

2005 ◽  
Vol 42 (2) ◽  
pp. 243-257 ◽  
Author(s):  
Alexander P Wolfe ◽  
Mark B Edlund
Keyword(s):  
British Columbia ◽  
Middle Eocene ◽  
Life Strategy ◽  
Centric Diatom ◽  
Evolutionary Trajectory ◽  
The Family ◽  
Freshwater Diatoms ◽  
Marine Realm ◽  
Diatom Genus ◽  
Early Cenozoic

A new centric diatom genus is described from laminated freshwater sediments of Middle Eocene age near Horsefly, British Columbia, Canada. This diatom, Eoseira wilsonii gen. et sp. nov., grew in filaments that constitute dense monospecific sub-horizons within the white couplets that represent summer deposition in the varved sequence. Although Eoseira clearly belongs within the Family Aulacoseiraceae, several features distinguish its valve structure from Aulacoseira. Gigantism of spines and the lack of geometric relationships between spine position and mantle areolae are the most conspicuous features of the genus. Eoseira is among the oldest freshwater diatoms known and one of relatively few extinct freshwater genera. In addition to serving as a potential biostratigraphic marker, Eoseira is a cornerstone to undertanding the evolutionary trajectory of the Aulacoseiraceae, likely the oldest family of freshwater diatoms. As such, it refines our understanding of early radiations from the marine realm in western North America. Furthermore, paleoecological inferences based on Eoseira life strategy pertain directly to limnological conditions during early Cenozoic hot-house conditions.

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