scholarly journals Distribution and morphological variability of Cyclotella-taxa in the late glacial of Längsee (Austria)

2007 ◽  
Author(s):  
K. Huber
Keyword(s):  
Morphological Variability ◽  
Late Glacial

scholarly journals The last glacial-interglacial cycle in Lake Ohrid (Macedonia/Albania): testing diatom response to climate

2010 ◽  
Vol 7 (10) ◽  
pp. 3083-3094 ◽  
Author(s):  
J. M. Reed ◽  
A. Cvetkoska ◽  
Z. Levkov ◽  
H. Vogel ◽  
B. Wagner
Keyword(s):  
Morphological Variability ◽  
Central Area ◽  
Late Glacial ◽  
Early Holocene ◽  
Future Research ◽  
Lake Basin ◽  
Last Interglacial ◽  
Lake Ohrid ◽  
Last Glacial ◽  
The Last Glacial

Abstract. Lake Ohrid is a site of global importance for palaeoclimate research. This study presents results of diatom analysis of a ca. 136 ka sequence, Co1202, from the northeast of the lake basin. It offers the opportunity to test diatom response across two glacial-interglacial transitions and within the Last Glacial, while setting up taxonomic protocols for future research. The results are outstanding in demonstrating the sensitivity of diatoms to climate change, providing proxy evidence for temperature change marked by glacial-interglacial shifts between the dominant planktonic taxa, Cyclotella fottii and C. ocellata, and exact correlation with geochemical proxies to mark the start of the Last Interglacial at ca. 130 ka. Importantly, diatoms show much stronger evidence in this site for warming during MIS3 than recorded in other productivity-related proxies, peaking at ca. 39 ka, prior to the extreme conditions of the Last Glacial maximum. In the light of the observed patterns, and from the results of analysis of early Holocene sediments from a second core, Lz1120, the lack of a response to Late Glacial and early Holocene warming from ca. 14.7–6.9 ka suggests the Co1202 sequence may be compromised during this phase. After ca. 7.4 ka, there is evidence for enhanced nutrient enrichment compared to the Last Interglacial, followed by a post-Medieval loss of diversity which is consistent with cooling, but not definitive. Taxonomically, morphological variability in C. fottii shows no clear trends linked to climate, but an intriguing change in central area morphology occurs after ca. 48.7 ka, coincident with a tephra layer. In contrast, C. ocellata shows morphological variation in the number of ocelli between interglacials, suggesting climatically-forced variation or evolutionary selection pressure. The application of a simple dissolution index does not track preservation quality very effectively, underlining the importance of diatom accumulation data in future studies.

On the morphological variability and systematic position of Cyclotella rossii Håkansson (Bacillariophyta)

2019 ◽  
pp. 159-161
Author(s):  
Sergei I. Genkal
Keyword(s):  
Morphological Variability ◽  
Systematic Position ◽  
Published Data

Based on the original and published data, it is suggested to refer Pantocsekiella rossii to the synonymy of Pantocsekiella chantaica and extend the diagnosis of the latter.

Morphological Variability of Some Bacillariophyta Species of the Genus Kobayasiella Lange-Bertalot (Raphales, Naviculaceae)

2019 ◽  
Vol 21 (4) ◽  
pp. 311-320
Author(s):  
S. I. Genkal ◽  
D. A. Kapustin ◽  
A. S. Stenina ◽  
I. N. Sterlyagova ◽  
Yu. N. Shabalina
Keyword(s):  
Morphological Variability

On the morphological variability of Navicula schmassmannii (Bacillariophyta)

2010 ◽  
Vol 44 ◽  
pp. 32-38 ◽  
Author(s):  
S. I. Genkal ◽  
W. G. Kharitonov
Keyword(s):  
Morphological Variability ◽  
Central Area ◽  
Diatom Species ◽  
Species Diagnosis ◽  
Wide Variability ◽  
Ultraoligotrophic Lake

On the basis of the studied materials from the ultraoligotrophic lake Elgygytgyn (Chukotka), a rare for the flora of Russia diatom species Navicula schmassmannii was recorded. In the studied populations of the species a wide variability of morphological quantitative (valve length and width, the number of stria in 10 μm) and qualitative (the shape of the valve and the central area) features was marked. It made the basis for emending of the species diagnosis.

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