Keeping Time Under the Midnight Sun: Behavioral and Plasma Melatonin Profiles of Free-Living Lapland Longspurs (Calcarius lapponicus) During the Arctic Summer

2012 ◽  
Vol 319 (1) ◽  
pp. 10-22 ◽  
Author(s):  
Noah T. Ashley ◽  
Ingrid Schwabl ◽  
Wolfgang Goymann ◽  
C. Loren Buck
Keyword(s):  
The Arctic ◽  
Free Living ◽  
Plasma Melatonin ◽  
Calcarius Lapponicus ◽  
Arctic Summer

Persistent diel melatonin rhythmicity during the Arctic summer in free-living willow warblers

2009 ◽  
Vol 56 (1) ◽  
pp. 163-168 ◽  
Author(s):  
Bengt Silverin ◽  
Eberhard Gwinner ◽  
Thomas J. Van't Hof ◽  
Ingrid Schwabl ◽  
Leonida Fusani ◽  
...  
Keyword(s):  
The Arctic ◽  
Free Living ◽  
Arctic Summer

Hypothalamic-pituitary-adrenal axis changes allow seasonal modulation of corticosterone in a bird

1998 ◽  
Vol 274 (5) ◽  
pp. R1338-R1344 ◽  
Author(s):  
L. Michael Romero ◽  
Kiran K. Soma ◽  
John C. Wingfield
Keyword(s):  
Hypothalamic Pituitary Adrenal Axis ◽  
Corticotropin Releasing Factor ◽  
Arginine Vasotocin ◽  
Free Living ◽  
Hypothalamic Pituitary Adrenal ◽  
Adrenal Axis ◽  
Maximal Output ◽  
Calcarius Lapponicus ◽  
Corticosterone Release ◽  
Pituitary Adrenal Axis

We examined possible mechanisms underlying seasonal stress modulation in Lapland longspurs ( Calcarius lapponicus), a species that breeds and molts (the energetically costly replacement of feathers) in the Alaskan Arctic. Free-living Lapland longspurs show dramatically reduced maximal corticosterone release during molt compared with the breeding season, an effect lost in captive birds. Neither changes in corticosterone binding proteins nor the overall condition of the bird (assessed by weight and fat storage) can explain different seasonal corticosterone responses. Adrenal insensitivity also does not fully explain reduced maximal output because exogenous ACTH enhanced corticosterone release during molt. Exogenous ACTH in molting birds, however, cannot stimulate corticosterone to stress-induced levels during breeding, implying reduced adrenal capacity. Lapland longspur pituitaries appeared to respond to exogenous corticotropin-releasing factor, arginine vasotocin, and mesotocin (the avian equivalents of arginine vasopressin and oxytocin) during molt, suggesting that a mechanism upstream of the pituitary blunts corticosterone release. Taken together, these results indicate that seasonal modulation of corticosterone release in this species is controlled at multiple sites in the hypothalamic-pituitary-adrenal axis.

scholarly journals Effect of elevated CO<sub>2</sub> on the dynamics of particle attached and free living bacterioplankton communities in an Arctic fjord

2012 ◽  
Vol 9 (8) ◽  
pp. 10725-10755 ◽  
Author(s):  
M. Sperling ◽  
J. Piontek ◽  
G. Gerdts ◽  
A. Wichels ◽  
H. Schunck ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Atmospheric Carbon Dioxide ◽  
Intergenic Spacer ◽  
Extracellular Enzyme ◽  
The Arctic ◽  
Organic Substrates ◽  
Viral Lysis ◽  
Free Living ◽  
High Co2 ◽  
Carbon Dioxide Co2

Abstract. The increase in atmospheric carbon dioxide (CO2) results in acidification of the oceans, expected to lead to the fastest drop in ocean pH in the last 300 million years, if anthropogenic emissions are continued at present rate. Due to higher solubility of gases in cold waters and increased exposure to the atmosphere by decreasing ice cover, the Arctic Ocean will be among the areas most strongly affected by ocean acidification. Yet, the response of the plankton community of high latitudes to ocean acidification has not been studied so far. This work is part of the Arctic campaign of the European Project on Ocean Acidification (EPOCA) in 2010, employing 9 in situ mesocosms of about 45 000 l each to simulate ocean acidification in Kongsfjorden, Svalbard (78°56.2' N 11°53.6' E). In the present study, we investigated effects of elevated CO2 on the composition and richness of particle attached (PA; >3 μm) and free living (FL; <3 μm >0.2 μm) bacterial communities by Automated Ribosomal Intergenic Spacer Analysis (ARISA) in 6 of the mesocosms and the surrounding fjord, ranging from 185 to 1050 initial μatm pCO2. ARISA was able to resolve about 20–30 bacterial band-classes per sample and allowed for a detailed investigation of the explicit richness. Both, the PA and the FL bacterioplankton community exhibited a strong temporal development, which was driven mainly by temperature and phytoplankton development. In response to the breakdown of a picophytoplankton bloom (phase 3 of the experiment), number of ARISA-band classes in the PA-community were reduced at low and medium CO2 (∼180–600 μatm) by about 25%, while it was more or less stable at high CO2 (∼ 650–800 μatm). We hypothesise that enhanced viral lysis and enhanced availability of organic substrates at high CO2 resulted in a more diverse PA-bacterial community in the post-bloom phase. Despite lower cell numbers and extracellular enzyme activities in the post-bloom phase, bacterial protein production was enhanced in high CO2-treatments, suggesting a positive effect of community richness on this function and on carbon cycling by bacteria.

scholarly journals Corticosterone Responses in Wild Birds: The Importance of Rapid Initial Sampling

The Condor ◽  
2002 ◽  
Vol 104 (1) ◽  
pp. 129-135 ◽  
Author(s):  
L. Michael Romero ◽  
Robin C. Romero
Keyword(s):  
Stress Responses ◽  
Passer Domesticus ◽  
Free Living ◽  
House Sparrows ◽  
Zonotrichia Leucophrys ◽  
Elapsed Time ◽  
Corticosterone Response ◽  
Calcarius Lapponicus ◽  
Initial Sampling ◽  
Zonotrichia Leucophrys Gambelii

Abstract Corticosterone concentrations in birds usually rise in response to capture and handling, and it is often assumed that this change is predictable. We tested this assumption by leaving Gambel's White-crowned Sparrows (Zonotrichia leucophrys gambelii), House Sparrows (Passer domesticus), and Lapland Longspurs (Calcarius lapponicus) in nets or traps for 15 min following capture and comparing their corticosterone response over the next 60 min with birds removed immediately. White-crowned Sparrows and House Sparrows left in mist nets for 15 min and then bled had significantly elevated corticosterone concentrations compared to controls that were immediately removed from the net and bled. Corticosterone concentrations over the next 45 min of handling and restraint were similar between groups. In another experiment, White-crowned Sparrows and Lapland Longspurs were captured using seed-baited Potter traps. The corticosterone response of White-crowned Sparrows left in the trap for 15 min did not differ from White-crowned Sparrows removed immediately. Leaving Lapland Longspurs in the trap had no effect in the initial 10 min of handling and restraint, but at 30 and 60 min these birds had significantly lower corticosterone concentrations than longspurs removed immediately from the trap. These data indicate that failing to immediately remove birds from nets or traps can alter the corticosterone response to subsequent stressful stimuli in unpredictable ways. This result emphasizes that the elapsed time from capture is a critical variable in assessing stress responses in free-living birds. Respuestas de los Niveles de Corticosterona en Aves Silvestres: La Importancia de un Muestreo Inicial Inmediato Resumen. Las concentraciones de corticosterona en las aves usualmente aumentan en respuesta a la captura y manipulación, y muchas veces se supone que estos cambios son predecibles. Pusimos a prueba esta suposición reteniendo individuos de las especies Zonotrichia leucophrys gambelii, Passer domesticus y Calcarius lapponicus en redes o trampas durante los 15 minutos subsecuentes a la captura y comparamos sus respuestas en los niveles de corticosterona durante los siguientes 60 minutos con las de individuos removidos inmediatamente de las trampas y redes. Las muestras de sangre de Z. l. gambelii y P. domesticus que fueron obtenidas después de 15 minutos de retención en las redes tuvieron niveles de corticosterona significativamente más altos que las de los individuos control obtenidas inmediatamente después de la captura. Durante los 45 minutos siguientes de manipulación y captura, las concentraciones de corticosterona fueron similares entre los dos grupos. En otro experimento, Z. l. gambelii y C. lapponicus fueron capturados mediante trampas “Potter” cebadas con semillas. La respuesta en los niveles de corticosterona de Z. l. gambelii no fue diferente entre individuos retenidos en las trampas por 15 minutos e individuos removidos inmediatamente. Para individuos de C. lapponicus retenidos en las trampas no hubo un efecto durante los 10 minutos iniciales de manipulación y captura, pero a los 30 y 60 minutos estas aves tuvieron concentraciones significativamente menores que los individuos removidos inmediatamente. Estos resultados indican que al no remover inmediatamente a las aves de las redes o trampas, las respuestas en los niveles de corticosterona a estímulos estresantes pueden verse alteradas de una manera impredecible. Estos resultados enfatizan que en aves silvestres, el lapso de tiempo desde la captura es una variable crítica en la determinación de las respuestas al estrés.

scholarly journals PMCs and the water frost point in the Arctic summer mesosphere

2001 ◽  
Vol 28 (23) ◽  
pp. 4449-4452 ◽  
Author(s):  
Michael H. Stevens ◽  
Robert R. Conway ◽  
Christoph R. Englert ◽  
Michael E. Summers ◽  
Klaus U. Grossmann ◽  
...  
Keyword(s):  
The Arctic ◽  
Frost Point ◽  
Arctic Summer

On small particles in the Arctic summer boundary layer: observations at two different heights near Ny-Ålesund, Svalbard

Tellus B ◽  
2009 ◽  
Vol 61 (2) ◽  
pp. 473-482 ◽  
Author(s):  
JOHAN STRÖM ◽  
ANN-CHRISTINE ENGVALL ◽  
FRANK DELBART ◽  
RADOVAN KREJCI ◽  
RENATE TREFFEISEN
Keyword(s):  
Boundary Layer ◽  
The Arctic ◽  
Small Particles ◽  
Arctic Summer

Black carbon radiative forcing over the Indian Arctic station, Himadri during the Arctic Summer of 2012

2015 ◽  
Vol 157 ◽  
pp. 29-36 ◽  
Author(s):  
M.P. Raju ◽  
P.D. Safai ◽  
S.M. Sonbawne ◽  
C.V. Naidu
Keyword(s):  
Black Carbon ◽  
Radiative Forcing ◽  
The Arctic ◽  
Arctic Summer

Total sea ice concentration retrieval from the SSM/I 85.5 GHz channels during the arctic summer

1997 ◽  
Vol 62 (1) ◽  
pp. 63-76 ◽  
Author(s):  
Dan Lubin ◽  
Caren Garrity ◽  
RenéO. Ramseier ◽  
Robert H. Whritner
Keyword(s):  
Sea Ice ◽  
The Arctic ◽  
Sea Ice Concentration ◽  
Ice Concentration ◽  
Arctic Summer
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