351 research outputs found
Takayama Gen. Nov. (Gymondiniales, Dinophyceae) a new genus of unarmored dinoflagellates with sigmoid apical grooves, including the description of two new species
No full textA new potentially ichthyotoxic dinoflagellate genus, Takayama de Salas, Bolch, Botes et Hallegraeff gen. nov., is described with two new species isolated from Tasmanian (Australia) and South African coastal waters: T. tasmanica de Salas, Bolch et Hallegraeff, sp. nov. and T. helix, de Salas, Bolch, Botes et Hallegraeff, sp. nov. The genus and two species are characterized by LM and EM of field samples and laboratory cultures as well as large subunit rDNA sequences and HPLC pigment analyses of several cultured strains. The new Takayama species have sigmoid apical grooves and contain fucoxanthin and its derivatives as the main accessory pigments. Takayama tasmanica is similar to the previously described species Gymnodinium pulchellum Larsen, Gyrodinium acrotrochum Larsen, and G. cladochroma Larsen in its external morphology but differs from these in having two ventral pores, a large horseshoe-shaped nucleus, and a central pyrenoid with radiating chloroplasts that pass through the nucleus. It contains gyroxanthin-diester and a gyroxanthin-like accessory pigment, both of which are missing in T. helix. Takayama helix has an apical groove that is nearly straight while still being clearly inflected. A ventral pore or slit is present. It has numerous peripheral, strap shaped, and spiraling chloroplasts with individual pyrenoids and a solid ellipsoidal nucleus. The genus Takayama has close affinities to the genera Karenia and Karlodinium
Takayama Gen, Nov (Gymnodiniales, Dinophyceae), a new genus of unarmored Dinoflagellates with sigmoid apical grooves, including the description of two new species
No full textA new potentially ichthyotoxic dinoflagellate genus, Takayama de Salas, Bolch, Botes et Hallegraeff gen. nov., is described with two new species isolated from Tasmanian (Australia) and South African coastal waters: T. tasmanica de Salas, Bolch et Hallegraeff, sp. nov. and T. helix, de Salas, Bolch, Botes et Hallegraeff, sp. nov. The genus and two species are characterized by LM and EM of field samples and laboratory cultures as well as large subunit rDNA sequences and HPLC pigment analyses of several cultured strains. The new Takayama species have sigmoid apical grooves and contain fucoxanthin and its derivatives as the main accessory pigments. Takayama tasmanica is similar to the previously described species Gymnodinium pulchellum Larsen, Gyrodinium acrotrochum Larsen, and G. cladochroma Larsen in its external morphology but differs fromthese in having two ventral pores, a large horseshoe-shaped nucleus, and a central pyrenoid with radiating chloroplasts that pass through the nucleus. It contains gyroxanthin-diester and a gyroxanthin-like accessory pigment, both of which are missing in T. helix. Takayama helix has an apical groove that is nearly straight while still being clearly inflected. A ventral pore or slit is present. It has numerous peripheral, strap shaped, and spiraling chloroplasts with individual pyrenoids and a solid ellipsoidal nucleus. The genus Takayama has close affinities to the genera Karenia and Karlodinium
Early 21st century snow cover state over the western river basins of the Indus River system
No full textTracing glacier changes since the 1960s on the south slope of Mt. Everest (central Southern Himalaya) using optical satellite imagery
Get PDFThis contribution examines glacier changes on the south side of Mt. Everest
from 1962 to 2011 considering five intermediate periods using optical
satellite imagery. The investigated glaciers cover ~ 400 km2
and present among the largest debris coverage (32%)
and the highest elevations (5720 m) of the world. We found an overall
surface area loss of 13.0 ± 3.1% (median 0.42 ± 0.06 % a−1),
an upward shift of 182 ± 22 m (3.7 ± 0.5 m a−1)
in snow-line altitude (SLA), a terminus retreat of 403 ± 9 m (median
6.1 ± 0.2 m a−1), and an increase of 17.6 ± 3.1%
(median 0.20 ± 0.06% a−1) in debris coverage between 1962 and
2011. The recession process of glaciers has been relentlessly continuous
over the past 50 years. Moreover, we observed that (i) glaciers that have
increased the debris coverage have experienced a reduced termini retreat (r = 0.87,
p < 0.001). Furthermore, more negative mass balances (i.e.,
upward shift of SLA) induce increases of debris coverage (r = 0.79,
p < 0.001); (ii) since early 1990s, we observed a slight but statistically
insignificant acceleration of the surface area loss (0.35 ± 0.13% a−1
in 1962–1992 vs 0.43 ± 0.25% a−1 in 1992–2011),
but an significant upward shift of SLA which increased almost three times
(2.2 ± 0.8 m a−1 in 1962–1992 vs 6.1 ± 1.4 m a−1 in
1992–2011). However, the accelerated shrinkage in recent decades (both in
terms of surface area loss and SLA shift) has only significantly affected
glaciers with the largest sizes (> 10 km2), presenting
accumulation zones at higher elevations (r = 0.61, p < 0.001) and
along the preferable south–north direction of the monsoons. Moreover, the
largest glaciers present median upward shifts of the SLA (220 m) that are
nearly double than that of the smallest (119 m); this finding leads to a hypothesis
that Mt. Everest glaciers are shrinking, not only due to warming
temperatures, but also as a result of weakening Asian monsoons registered
over the last few decades. We conclude that the shrinkage of the glaciers in
south of Mt. Everest is less than that of others in the western and eastern
Himalaya and southern and eastern Tibetan Plateau. Their position in higher
elevations have likely reduced the impact of warming on these glaciers, but
have not been excluded from a relentlessly continuous and slow recession
process over the past 50 years
Abfallvermeidung durch eine neuartige Verfahrens- und Anlagentechnik zur Erzeugung funktioneller Hartchromschichten
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Morphology and phylogenetic affinities of Thecadinium foveolatum sp. nov. (Dinophyceae: Thecadiniaceae), a new marine benthic dinoflagellate from the west of Scotland
No full textA new chloroplast-containing species of the sand-dwelling benthic dinoflagellate Thecadinium was isolated and cultured from a single cell collected from shallow waters of the marine Loch Ewe in North West Scotland. The cultured cells are described by light and scanning electron microscopy and the genetic affinities examined by comparison of ribosomal RNA gene sequences. Thecadinium foveolatum Bolch sp. nov. is heavily armoured with thecal plates that are ornamented with evenly distributed pores and contains numerous globular, dark golden-brown chloroplasts. Cells are broadly ovoid and slightly laterally compressed, with a descending cingulum displaced approximately half of the cell width. The thick thecal plates, numerous pores and the strongly displaced cingulum clearly differentiate this species from the only other chloroplast-containing species, T. kofoidii, and the remaining non-photosynthetic Thecadinium species described. Analysis of large-subunit rDNA sequences of Thecadinium foveolatum and other members of the Peridiniphycidae indicate that this new species is allied to the gonyaulacalean lineage rather than the peridinialean taxa included in the analyses
Glacier area and mass changes since 1964 in the Ala Archa Valley, Kyrgyz Ala-Too, northern Tien Shan
Get PDFGlaciers are an important source of fresh water for Central Asia as they release water during the summer months when precipitation is low and water demand highest. Many studies address glacier area changes but only changes in glacier mass can be directly linked to climate and runoff. Despite the importance, investigations of glacier mass changes have been restricted to only a few glaciers in the Tien Shan until now. Geodetic mass balance measurements are suitable to complement and extend existing in-situ measurements. In this study, both area and mass changes of the ~40 km² glacier ice in the Ala Archa Valley, Kyrgyz Tien Shan, were investigated using 1964 and 1971 stereo Corona, 2012 stereo ASTER, the SRTM digital terrain model and other optical data such as Landsat ETM+ or Rapid Eye. In addition, ice thickness was modeled taking the basal shear stress and the glacier surface topography into account. The results indicate an area loss of 18.3±5.0% from 1964 until 2010 with continuous shrinkage in all investigated periods. The glacier’s mass balance was −0.45±0.27 m w.e. a⁻¹ for the period 1964–1999 and −0.42±0.66 m w.e. a⁻¹ for 1999–2012. Golubin Glacier showed a possible slight mass gain for 1964–1971 and a decelerated mass loss for the 1999–2012 period. This is in good agreement with existing in-situ measurements exiting from 1962 until 1994 and since 2010. The overall ice volume was estimated to be 1.56±0.47 km³ of ice in the year 2000. Hence, the entire ice would be lost by 2100 if the mass loss would continue at the same rate
Glacier characteristics and changes in the Sary-Jaz River Basin (Central Tien Shan, Kyrgyzstan) – 1990–2010
Get PDFThe water discharge from the heavily glacierized Sary-Jaz River Basin (Eastern Kyrgyzstan) is of high importance for the very arid Tarim Basin located in Xinjiang (north-western China). We investigated glacier changes in the entire Sary-Jaz River Basin, which covers a large part of the Central Tien Shan, for the period from 1990 to 2010 based on Landsat ‘TM’/‘ETM+’data. We found 1310 glaciers (>0.1 km²), which covered 2055 ± 41.1 km² (∼18% of the entire basin) in 1990. The glaciers shrank by 77.1 ± 57.1 km² (3.7 ± 2.7%) until 2010. This is considerably lower than in most other ranges of the Tien Shan. The lowest insignificant area loss (−1.5 ± 2.7%) was found in the eastern part of the basin where the largest glaciers and highest peaks are situated. Debris-covered glaciers shrank significantly less than clean-ice glaciers of comparable size. We also identified a few advancing glaciers which show surge characteristics. Climate data from the Tien Shan weather station (3614 m asl.) close to the study region showed no significant long-term trend
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