scholarly journals Late summer distribution and abundance of ice-associated whales in the Norwegian High Arctic

2017 ◽  
Vol 32 ◽  
pp. 59-70 ◽  
Author(s):  
J Vacquié-Garcia ◽  
C Lydersen ◽  
TA Marques ◽  
J Aars ◽  
H Ahonen ◽  
...  
Keyword(s):  
Late Summer ◽  
High Arctic ◽  
Summer Distribution

scholarly journals Late Summer Distribution of Cetaceans near Barrow, Alaska: Results from Aerial Surveys Conducted During the Bowhead Whale Feeding Ecology Study, 2007–11

2018 ◽  
Vol 79 (2) ◽  
pp. 1-22
Author(s):  
Kim E. W. Shelden ◽  
Julie A. Mocklin ◽  
Kimberly T. Goetz ◽  
David J. Rugh ◽  
Linda Vate Brattström ◽  
...  
Keyword(s):  
Feeding Ecology ◽  
Late Summer ◽  
Bowhead Whale ◽  
Aerial Surveys ◽  
Summer Distribution

scholarly journals Recent ice cap snowmelt in Russian High Arctic and anti-correlation with late summer sea ice extent

2014 ◽  
Vol 9 (4) ◽  
pp. 045009 ◽  
Author(s):  
Meng Zhao ◽  
Joan Ramage ◽  
Kathryn Semmens ◽  
Friedrich Obleitner
Keyword(s):  
Sea Ice ◽  
Late Summer ◽  
High Arctic ◽  
Sea Ice Extent ◽  
Ice Cap

Winter mortality and the function of larval hibernacula during the 14-year life cycle of an arctic moth, Gynaephora groenlandica

1995 ◽  
Vol 73 (4) ◽  
pp. 657-662 ◽  
Author(s):  
Olga Kukal
Keyword(s):  
Plant Cover ◽  
Late Summer ◽  
High Arctic ◽  
The Arctic ◽  
Mortality Factor ◽  
Winter Mortality ◽  
Mortality Factors ◽  
Primary Host ◽  
Larval Behaviour ◽  
Gynaephora Groenlandica

Larvae of the arctic moth Gynaephora groenlandica stop feeding and spin silk hibernacula before the peak of summer season in the Canadian High Arctic Archipelago. This study examines the function of these hibernacula in relation to the biotic and abiotic mortality factors of parasitism and temperature. Winter mortality of 10% among larvae in cages on the tundra was compared with previous results on parasitism (56% mortality). Prior to winter, the cages were used to record larval behaviour and the location of hibernacula. The majority of the larvae (81%) spun hibernacula, most of which were concealed between the stems of arctic heather, Cassiope tetragona. Fewer hibernacula were found on the primary host plant, arctic willow, Salix arctica, than on C. tetragona or Dryas integrifolia, which formed the dominant plant cover. Nearly one-half of all the larvae that spun hibernacula made joint hibernacula with other larvae. Frequency of larvae sharing hibernacula declined with increasing numbers of larvae per cage. At low population density about half of the larvae occupied communal hibernacula, whereas only one-quarter of the larvae at high density shared hibernacula. In most cases only 2 larvae spun a common hibernaculum, 3 larvae shared hibernacula less frequently, and greater numbers of larvae were rarely found in a single hibernaculum. Unlike the high excess body temperatures usually achieved through thermoregulation by feeding larvae and pupae, temperatures within hibernacula were nearly identical with those of the surrounding substrate over 18 h and rose < 5 °C during the afternoon. This study suggests that larval hibernacula lower summer and winter mortality of G. groenlandica larvae. Hibernacula are an effective barrier to parasitism, which is the primary mortality factor. Furthermore, the behavioural shift from feeding to spinning hibernacula may prevent energy depletion by inducing metabolic depression during mid to late summer, which may be essential for winter survival.

scholarly journals Emerging dominance of summer rainfall in driving High Arctic terrestrial-aquatic connectivity

2020 ◽  
Author(s):  
Casey Beel ◽  
Joanne Heslop ◽  
John Orwin ◽  
Michael Pope ◽  
Amanda Schevers ◽  
...  
Keyword(s):  
Late Summer ◽  
Summer Rainfall ◽  
High Arctic ◽  
Particulate Material ◽  
Buffering Capacity ◽  
Transport Pathways ◽  
Rainfall Events ◽  
Aquatic Connectivity ◽  
Doc Export ◽  
Order Of Magnitude

Abstract Climate warming-related hydrological transformations are changing material mobilization, composition, and transport pathways along the terrestrial-aquatic continuum. Here, we integrate decade-long hydrometeorological and biogeochemical data from the High Arctic to show that annual fluvial energy is shifting from a skewed (snowmelt-dominated) to a multi-modal (snowmelt- and rainfall-dominated) distribution. This shift enhanced terrestrial-aquatic connectivity for dissolved and particulate material fluxes, but to overcome the watersheds’ buffering capacity for particulate material rainfall events had to increase by an order of magnitude. Permafrost disturbances (< 3 % of the watersheds’ areal extent) reduced watershed-scale DOC export enough to offset concurrent increased DOC export in undisturbed watersheds but play a weaker role in altering C export than the increased magnitude and frequency of late summer rainfall events. However, the disturbances have primed the landscape for accelerated geomorphic change when future rainfall magnitudes and consequent pluvial responses exceed the current buffering capacity of the terrestrial-aquatic continuum.

scholarly journals Emerging dominance of summer rainfall driving High Arctic terrestrial-aquatic connectivity

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
C. R. Beel ◽  
J. K. Heslop ◽  
J. F. Orwin ◽  
M. A. Pope ◽  
A. J. Schevers ◽  
...  
Keyword(s):  
Late Summer ◽  
Summer Rainfall ◽  
High Arctic ◽  
Particulate Material ◽  
Buffering Capacity ◽  
Stream Power ◽  
Material Transfer ◽  
Carbon Export ◽  
Aquatic Connectivity ◽  
Order Of Magnitude

AbstractHydrological transformations induced by climate warming are causing Arctic annual fluvial energy to shift from skewed (snowmelt-dominated) to multimodal (snowmelt- and rainfall-dominated) distributions. We integrated decade-long hydrometeorological and biogeochemical data from the High Arctic to show that shifts in the timing and magnitude of annual discharge patterns and stream power budgets are causing Arctic material transfer regimes to undergo fundamental changes. Increased late summer rainfall enhanced terrestrial-aquatic connectivity for dissolved and particulate material fluxes. Permafrost disturbances (<3% of the watersheds’ areal extent) reduced watershed-scale dissolved organic carbon export, offsetting concurrent increased export in undisturbed watersheds. To overcome the watersheds’ buffering capacity for transferring particulate material (30 ± 9 Watt), rainfall events had to increase by an order of magnitude, indicating the landscape is primed for accelerated geomorphological change when future rainfall magnitudes and consequent pluvial responses exceed the current buffering capacity of the terrestrial-aquatic continuum.

scholarly journals Terrestrial Inputs Shape Coastal Bacterial and Archaeal Communities in a High Arctic Fjord (Isfjorden, Svalbard)

2021 ◽  
Vol 12 ◽  
Author(s):  
Lisa-Marie Delpech ◽  
Tobias R. Vonnahme ◽  
Maeve McGovern ◽  
Rolf Gradinger ◽  
Kim Præbel ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Coastal Waters ◽  
Environmental Gradients ◽  
Late Summer ◽  
High Arctic ◽  
Atlantic Water ◽  
The Arctic ◽  
Rrna Gene ◽  
Terrestrial Runoff ◽  
Terrestrial Inputs

The Arctic is experiencing dramatic changes including increases in precipitation, glacial melt, and permafrost thaw, resulting in increasing freshwater runoff to coastal waters. During the melt season, terrestrial runoff delivers carbon- and nutrient-rich freshwater to Arctic coastal waters, with unknown consequences for the microbial communities that play a key role in determining the cycling and fate of terrestrial matter at the land-ocean interface. To determine the impacts of runoff on coastal microbial (bacteria and archaea) communities, we investigated changes in pelagic microbial community structure between the early (June) and late (August) melt season in 2018 in the Isfjorden system (Svalbard). Amplicon sequences of the 16S rRNA gene were generated from water column, river and sediment samples collected in Isfjorden along fjord transects from shallow river estuaries and glacier fronts to the outer fjord. Community shifts were investigated in relation to environmental gradients, and compared to river and marine sediment microbial communities. We identified strong temporal and spatial reorganizations in the structure and composition of microbial communities during the summer months in relation to environmental conditions. Microbial diversity patterns highlighted a reorganization from rich communities in June toward more even and less rich communities in August. In June, waters enriched in dissolved organic carbon (DOC) provided a niche for copiotrophic taxa including Sulfitobacter and Octadecabacter. In August, lower DOC concentrations and Atlantic water inflow coincided with a shift toward more cosmopolitan taxa usually associated with summer stratified periods (e.g., SAR11 Clade Ia), and prevalent oligotrophic marine clades (OM60, SAR92). Higher riverine inputs of dissolved inorganic nutrients and suspended particulate matter also contributed to spatial reorganizations of communities in August. Sentinel taxa of this late summer fjord environment included taxa from the class Verrucomicrobiae (Roseibacillus, Luteolibacter), potentially indicative of a higher fraction of particle-attached bacteria. This study highlights the ecological relevance of terrestrial runoff for Arctic coastal microbial communities and how its impacts on biogeochemical conditions may make these communities susceptible to climate change.

scholarly journals Distribution and abundance of Canadian High Arctic belugas, 1974-1979

2002 ◽  
Vol 4 ◽  
pp. 87 ◽  
Author(s):  
William R Koski ◽  
Kerwin J Finley
Keyword(s):  
Late Summer ◽  
High Arctic ◽  
Delphinapterus Leucas ◽  
Polar Cod ◽  
Canadian High Arctic ◽  
Devon Island ◽  
The North ◽  
Polar Cod Boreogadus Saida ◽  
North Water ◽  
Somerset Island

We conducted >236,000 km of aerial surveys and some supplementary studies of belugas (Delphinapterus leucas) in the central and eastern Canadian High Arctic in 974-79. Belugas that wintered in the “North Water” in Baffin Bay moved southwest into Lancaster Sound in April and early May. The main westward migration into Lancaster Sound occurred over a 2 to 3 week period during late June to late July. Estuaries along Somerset Island were occupied for <3 weeks from mid-July to mid-August. Little feeding occurred in estuaries. From mid-August until fall migration began in mid-September belugas occupied estuaries and offshore waters in Peel Sound. Fall migration eastward through Lancaster Sound was exclusively along the south coast of Devon Island, highly co-ordinated, and rapid; most of the population passed through the sound in <1 week. The whales then moved north along the east coast of Devon Island; some entered Jones Sound while others crossed directly to SE Ellesmere Island. Most calving occurred in July and early August; calving was not seen in estuaries and probably occurred offshore. Excluding calves, adults and yearlings formed 77% and 8.4%, respectively, of the population. The proportion of calves during mid-August was consistent with a triennial calving cycle. During late summer, belugas fed on coastal concentrations of polar cod (Boreogadus saida), under pan ice offshore (probably on cod), and in deep offshore waters. The size of the Canadian High Arctic population in the late 1970s was estimated to be at least 10,250 to 12,000 animals without allowing for animals that may have passed between surveys or that were below the surface at the time of the counts.

scholarly journals Modeling Late-Summer Distribution of Golden Eagles (Aquila chrysaetos) in the Western United States

PLoS ONE ◽  
2016 ◽  
Vol 11 (8) ◽  
pp. e0159271 ◽  
Author(s):  
Ryan M. Nielson ◽  
Robert K. Murphy ◽  
Brian A. Millsap ◽  
William H. Howe ◽  
Grant Gardner
Keyword(s):  
United States ◽  
Late Summer ◽  
Western United States ◽  
Aquila Chrysaetos ◽  
Golden Eagles ◽  
Summer Distribution

Habitat selection by juvenile coho salmon in response to food and woody debris manipulations in suburban and rural stream sections

2000 ◽  
Vol 57 (9) ◽  
pp. 1804-1813 ◽  
Author(s):  
Guillermo Roberto Giannico
Keyword(s):  
Habitat Selection ◽  
Coho Salmon ◽  
Woody Debris ◽  
Dominant Role ◽  
Oncorhynchus Kisutch ◽  
Late Summer ◽  
Abundant Food ◽  
Summer Distribution ◽  
Habitat Enhancement

This study explored the effects of food and woody debris manipulations on the summer distribution of juvenile coho salmon (Oncorhynchus kisutch) in small suburban streams. To examine fish responses to these factors, three different experiments were carried out in modified sections of two streams. The results showed that the distribution of juvenile coho salmon in a stream section was primarily controlled by the availability and distribution of food among pools and by the presence and density of woody debris. Food, however, played a dominant role because the foraging quality of a pool not only affected the density of fish in it but also the response of those fish towards instream debris. In food-rich stream sections, low proportions of juvenile coho salmon occupied pools with dense woody debris in the spring, which changed towards late summer. In contrast, in food-poor reaches, high proportions of fish were found in pools with abundant debris in the spring. Pools that combined abundant food with sparse woody debris were the most favoured by the fish. It is important that salmonid habitat enhancement projects consider that open foraging areas interspersed with woody debris characterize the type of summer habitat that juvenile coho salmon prefer.

Marine zooplanktonic and benthic community respiration rates at Resolute, Canadian high Arctic

1997 ◽  
Vol 54 (5) ◽  
pp. 995-1005 ◽  
Author(s):  
H E Welch ◽  
T D Siferd ◽  
P Bruecker
Keyword(s):  
Benthic Community ◽  
Ecosystem Respiration ◽  
Seasonal Pattern ◽  
Late Summer ◽  
Dry Weight ◽  
High Arctic ◽  
Early Summer ◽  
Community Respiration ◽  
Respiration Rates ◽  
Total Ecosystem Respiration

Benthic community respiration rates and macrozooplankton (>202 µm) biomass and respiration rates were measured throughout a calender year at Resolute (74°42 prime N, 94°50 prime W). The plankton averaged 7.2 g dry weight · m-2 with no seasonal pattern and respired 82 g O2 · m-2 · yr-1. Gelatinous and chaetognath predators made up 10% of macrozooplankton biomass and respired 6.4% of planktonic respiration. The lipid content of the nongelatinous fraction fluctuated seasonaly from 64% of dry weight in midwinter to 46% in early summer. The benthic soft-bottom community inside Resolute Bay respired about 125 g O2 · m-2 · yr-1, with a twofold rate increase in late summer. Offshore on hard bottom the few measurements we obtained suggested a respiration rate of about 75 g O2 · m-2 · yr-1. The macrozooplankton and benthos were therefore approximately equal in energy flow. The total ecosystem respiration of 157 g O2 · m-2 · yr-1 corroborated a previous independent estimate of photosynthesis of 60 g C · m-2 · yr-1 for the region. Microplankton respiration appeared to be relatively low. Our results are consistent with the hypothesis that the proporion of primary production exported to the benthos increases with decreasing water temperature and depth, increasing latitude, and increasing cell size.

Sign in / Sign up

Export Citation Format

Share Document