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Sea-ice habitat preference of the Pa...

Sacco, Alexander Edward.

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Sea-ice habitat preference of the Pacific walrus (Odobenus rosmarus divergens) in the Bering Sea: A multiscaled approach.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Sea-ice habitat preference of the Pacific walrus (Odobenus rosmarus divergens) in the Bering Sea: A multiscaled approach./
作者:	Sacco, Alexander Edward.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2015,
面頁冊數:	137 p.
附註:	Source: Masters Abstracts International, Volume: 55-03.
Contained By:	Masters Abstracts International55-03(E).
標題:	Geophysics. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=1605428
ISBN:	9781339321851

Sea-ice habitat preference of the Pacific walrus (Odobenus rosmarus divergens) in the Bering Sea: A multiscaled approach.
Sacco, Alexander Edward.

Sea-ice habitat preference of the Pacific walrus (Odobenus rosmarus divergens) in the Bering Sea: A multiscaled approach. - Ann Arbor : ProQuest Dissertations & Theses, 2015 - 137 p.

Source: Masters Abstracts International, Volume: 55-03.

Thesis (M.S.)--University of Alaska Fairbanks, 2015.

The goal of this thesis is to define specific parameters of mesoscale sea-ice seascapes for which walruses show preference during important periods of their natural history. This research thesis incorporates sea-ice geophysics, marine-mammal ecology, remote sensing, computer vision techniques, and traditional ecological knowledge of indigenous subsistence hunters in order to quantitatively study walrus preference of sea ice during the spring migration in the Bering Sea. Using an approach that applies seascape ecology, or landscape ecology to the marine environment, our goal is to define specific parameters of ice patch descriptors, or mesoscale seascapes in order to evaluate and describe potential walrus preference for such ice and the ecological services it provides during an important period of their life-cycle.

ISBN: 9781339321851Subjects--Topical Terms:

535228
Geophysics.

Sea-ice habitat preference of the Pacific walrus (Odobenus rosmarus divergens) in the Bering Sea: A multiscaled approach.
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100 1 $a Sacco, Alexander Edward. $3 3282828
245 1 0 $a Sea-ice habitat preference of the Pacific walrus (Odobenus rosmarus divergens) in the Bering Sea: A multiscaled approach.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2015
300 $a 137 p.
500 $a Source: Masters Abstracts International, Volume: 55-03.
500 $a Adviser: Andrew R. Mahoney.
502 $a Thesis (M.S.)--University of Alaska Fairbanks, 2015.
520 $a The goal of this thesis is to define specific parameters of mesoscale sea-ice seascapes for which walruses show preference during important periods of their natural history. This research thesis incorporates sea-ice geophysics, marine-mammal ecology, remote sensing, computer vision techniques, and traditional ecological knowledge of indigenous subsistence hunters in order to quantitatively study walrus preference of sea ice during the spring migration in the Bering Sea. Using an approach that applies seascape ecology, or landscape ecology to the marine environment, our goal is to define specific parameters of ice patch descriptors, or mesoscale seascapes in order to evaluate and describe potential walrus preference for such ice and the ecological services it provides during an important period of their life-cycle.
520 $a The importance of specific sea-ice properties to walrus occupation motivates an investigation into how walruses use sea ice at multiple spatial scales when previous research suggests that walruses do not show preference for particular floes. Analysis of aerial imagery, using image processing techniques and digital geomorphometric measurements (floe size, shape, and arrangement), demonstrated that while a particular floe may not be preferred, at larger scales a collection of floes, specifically an ice patch (< 4 km2), was preferred. This shows that walruses occupy ice patches with distinct ice features such as floe convexity, spatial density, and young ice and open water concentration. Ice patches that are occupied by adult and juvenile walruses show a small number of characteristics that vary from those ice patches that were visually unoccupied. Using synthetic aperture radar imagery, we analyzed co-located walrus observations and statistical texture analysis of radar imagery to quantify seascape preferences of walruses during the spring migration. At a coarse resolution of 100 -- 9,000 km2, seascape analysis shows that, for the years 2006 -- 2008, walruses were preferentially occupying fragmented pack ice seascapes range 50 -- 89% of the time, when, all throughout the Bering Sea, only range 41 -- 46% of seascapes consisted of fragmented pack ice.
520 $a Traditional knowledge of a walrus' use of sea ice is investigated through semi-directed interviews conducted with subsistence hunters and elders from Savoonga and Gambell, two Alaskan Native communities on St. Lawrence Island, Alaska. Informants were provided with a large nautical map of the land and ocean surrounding St. Lawrence Island and 45 printed large-format aerial photographs of walruses on sea ice to stimulate discussion as questions were asked to direct the topics of conversation. Informants discussed change in sea ice conditions over time, walrus behaviors during the fall and spring subsistence hunts, and sea-ice characteristics that walruses typically occupy. These observations are compared with ice-patch preferences analyzed from aerial imagery. Floe size was found to agree with remotely-sensed ice-patch analysis results, while floe shape was not distinguishable to informants during the hunt. Ice-patch arrangement descriptors concentration and density generally agreed with ice-patch analysis results.
520 $a Results include possible preference of ice-patch descriptors at the ice-patch scale and fragmented pack ice preference at the seascape scale. Traditional knowledge suggests large ice ridges are preferential sea-ice features at the ice-patch scale, which are rapidly becoming less common during the fall and spring migration of sea ice through the Bering Sea. Traditional knowledge, combined with a scientific analysis and field work to study species habitat preferences and, ultimately, habitat partitioning, can stem from these results. Future work includes increased sophistication of the synthetic aperture radar classification algorithm, experimentation with various spatial scales to determine the optimal scale for walrus' life-cycle events, and incorporation of further traditional knowledge to investigate and interface cross-cultural sea-ice observations, knowledge and science to determine sea ice importance to marine mammals in a changing Arctic.
590 $a School code: 0006.
650 4 $a Geophysics. $3 535228
650 4 $a Remote sensing. $3 535394
650 4 $a Ecology. $3 516476
690 $a 0373
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710 2 $a University of Alaska Fairbanks. $b Geology & Geophysics. $3 3183245
773 0 $t Masters Abstracts International $g 55-03(E).
790 $a 0006
791 $a M.S.
792 $a 2015
793 $a English
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