Karyological and endosymbiotic notes on two Choricystis species (Trebouxiophyceae, Chlorophyta)

Biologia ◽  
2009 ◽  
Vol 64 (1) ◽  
Author(s):  
Ralitsa Zidarova ◽  
Dobrina Temniskova ◽  
Balik Dzhambazov
Keyword(s):  
Paramecium Bursaria ◽  
Haploid Number ◽  
Lake Geneva ◽  
Short Discussion ◽  
Moss Sample ◽  
Maritime Antarctica ◽  
Symbiotic Associations ◽  
Livingston Island ◽  
Taxonomical Status ◽  
Choricystis Minor

AbstractTwo species of the genus Choricystis (Choricystis minor and Choricystis chodatii) have been chromosomally surveyed. In addition, their ability to form symbiotic associations with the ciliate Paramecium bursaria was also investigated. Choricystis minor (clone #8931/1 from strain #8931) was isolated from a moss sample collected on Livingston Island, Maritime Antarctica. Choricystis chodatii (clone #3090/1) was derived from strain #3090 Chodat-type culture (loc. Switzerland, lake Geneva). The karyotypes of both species showed a haploid number of five chromosomes and shared some similarity in the chromosome lengths. The absolute chromosome lengths ranged from 1.25 µm to 2.95 µm. Studied species possess equal abilities for endosymbiotic associations with Paramecium bursaria. Descriptions of the species and a short discussion on their taxonomical status are given.

Rapid denudation processes in cryptogamic communities from Maritime Antarctica subjected to human trampling

2013 ◽  
Vol 25 (2) ◽  
pp. 318-328 ◽  
Author(s):  
L.R. Pertierra ◽  
F. Lara ◽  
P. Tejedo ◽  
A. Quesada ◽  
J. Benayas
Keyword(s):  
Water Content ◽  
Current Trend ◽  
Cumulative Impacts ◽  
Maritime Antarctica ◽  
Peat Soils ◽  
Lichen Community ◽  
Livingston Island ◽  
The Impact ◽  
Human Trampling ◽  
Initial Coverage

AbstractThis study explores the impact of human trampling on moss and lichen dominated communities of Maritime Antarctica. A simulation of trampling was performed on previously unaffected plots of different terricolous cryptogamic assemblages at Byers Peninsula, Livingston Island. The communities studied were: 1) a uniform moss carpet, 2) a heterogeneous moss assemblage composed of hummocks and turfs, and 3) a fellfield lichen community. All communities analysed were extremely sensitive but different denudation processes were observed. None of the plots maintained 50% of initial coverage after 200 pedestrian transits. Even very low trampling intensity resulted in disturbance at all plots. Sensitivities of the different communities were identified in order to formulate recommendations for minimizing the trampling impacts. In our study the lichen dominated community on dry exposed soils exhibited the lowest resistance to trampling. For moss communities, lower resistance was found in peat soils with higher water content and biomass. With the current trend of increasing human presence in Antarctica, we predict that the cumulative impacts of trampling over future decades will adversely affect all types of moss and lichen communities.

Limnological characteristics of the freshwater ecosystems of Byers Peninsula, Livingston Island, in maritime Antarctica

Polar Biology ◽  
2006 ◽  
Vol 30 (5) ◽  
pp. 635-649 ◽  
Author(s):  
M. Toro ◽  
A. Camacho ◽  
C. Rochera ◽  
E. Rico ◽  
M. Bañón ◽  
...  
Keyword(s):  
Freshwater Ecosystems ◽  
Maritime Antarctica ◽  
Livingston Island

Nematode communities of Byers Peninsula, Livingston Island, maritime Antarctica

2011 ◽  
Vol 23 (4) ◽  
pp. 349-357 ◽  
Author(s):  
Uffe N. Nielsen ◽  
Diana H. Wall ◽  
Grace Li ◽  
Manuel Toro ◽  
Byron J. Adams ◽  
...  
Keyword(s):  
Community Composition ◽  
Abiotic Factors ◽  
Biotic Interactions ◽  
Terrestrial Ecosystems ◽  
Nematode Species ◽  
Trophic Group ◽  
Maritime Antarctica ◽  
Nematode Communities ◽  
Livingston Island ◽  
Harsh Conditions

AbstractThe nematode communities of Antarctica are considered simple. The few species present are well adapted to the harsh conditions and often endemic to Antarctica. Knowledge of Antarctic terrestrial ecosystems is increasing rapidly, but nematode communities remain to be explored in large parts of Antarctica. In soil samples collected at Byers Peninsula (Antarctic Specially Protected Area No. 126), Livingston Island we recorded 37 nematode taxa but samples showed great variation in richness and abundance. Nematode richness decreased with increasing soil pH, whereas total abundances, and the abundance of several trophic groups, were greatest at intermediate pH (around 6.5–7). Moreover, the community composition was mainly related to pH and less so to soil moisture. Trophic group, and total nematode, rotifer and tardigrade, abundances were generally positively correlated. Byers Peninsula is thus, by maritime Antarctic standards, a nematode biodiversity hotspot, and the presence of several previously unrecorded genera indicates that nematode species richness in maritime Antarctica is probably underestimated. Our results indicate that abiotic factors influence nematode communities with little evidence for biotic interactions. The unexplained heterogeneity in community composition is probably related to variation in microclimate, vegetation, topography and unmeasured soil properties, but may also be contributed to by biological processes.

scholarly journals Mapping snow cover and snow depth across the Lake Limnopolar watershed on Byers Peninsula, Livingston Island, Maritime Antarctica

2013 ◽  
Vol 25 (2) ◽  
pp. 157-166 ◽  
Author(s):  
S.R. Fassnacht ◽  
J.I. López-Moreno ◽  
M. Toro ◽  
D.M. Hultstrand
Keyword(s):  
Snow Cover ◽  
Snow Depth ◽  
Regression Trees ◽  
Snow Accumulation ◽  
Maritime Antarctica ◽  
Density Profiles ◽  
Livingston Island ◽  
Digital Elevation ◽  
Depth Classification ◽  
Elevation Model

AbstractFew parts of Antarctica are not permanently covered in ice. The retreat of the ice sheet from Byers Peninsula on western Livingston Island, Maritime Antarctica, has provided a new area of seasonal snow cover. Snow surveys were conducted in late November 2008 at the time of peak accumulation across the 1 km2 Lake Limnopolar watershed. Topographic variables were derived from a digital elevation model to determine the variables controlling the presence or absence of snow and the distribution of snow depth. Classification with binary regression trees showed that wind related variables dominated the presence and depth of snow. The product of the sine of aspect and the sine of slope was the first variable in both regression trees. Density profiles were also measured and illustrated a relatively homogeneous snowpack over space at peak snow accumulation.

Distribution and characterization of soils and landform relationships in Byers Peninsula, Livingston Island, Maritime Antarctica

Geomorphology ◽  
2012 ◽  
Vol 155-156 ◽  
pp. 45-54 ◽  
Author(s):  
Pedro Adnet Moura ◽  
Marcio R. Francelino ◽  
Carlos Ernesto G.R. Schaefer ◽  
Felipe N.B. Simas ◽  
Bruno A.F. de Mendonça
Keyword(s):  
Maritime Antarctica ◽  
Livingston Island
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