scholarly journals Female Pacific walruses (Odobenus rosmarus divergens) show greater partitioning of sea ice organic carbon than males: Evidence from ice algae trophic markers

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0255686
Author(s):  
Chelsea W. Koch ◽  
Lee W. Cooper ◽  
Ryan J. Woodland ◽  
Jacqueline M. Grebmeier ◽  
Karen E. Frey ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Sea Ice ◽  
Nitrogen Isotopes ◽  
Chukchi Sea ◽  
Trophic Position ◽  
Ice Algae ◽  
Pacific Walrus ◽  
Odobenus Rosmarus Divergens ◽  
Odobenus Rosmarus ◽  
The Pacific

The expected reduction of ice algae with declining sea ice may prove to be detrimental to the Pacific Arctic ecosystem. Benthic organisms that rely on sea ice organic carbon (iPOC) sustain benthic predators such as the Pacific walrus (Odobenus rosmarus divergens). The ability to track the trophic transfer of iPOC is critical to understanding its value in the food web, but prior methods have lacked the required source specificity. We analyzed the H-Print index, based on biomarkers of ice algae versus phytoplankton contributions to organic carbon in marine predators, in Pacific walrus livers collected in 2012, 2014 and 2016 from the Northern Bering Sea (NBS) and Chukchi Sea. We paired these measurements with stable nitrogen isotopes (δ15N) to estimate trophic position. We observed differences in the contribution of iPOC in Pacific walrus diet between regions, sexes, and age classes. Specifically, the contribution of iPOC to the diet of Pacific walruses was higher in the Chukchi Sea (52%) compared to the NBS (30%). This regional difference is consistent with longer annual sea ice persistence in the Chukchi Sea. Within the NBS, the contribution of iPOC to walrus spring diet was higher in females (~45%) compared to males (~30%) for each year (p < 0.001), likely due to specific foraging behavior of females to support energetic demands associated with pregnancy and lactation. Within the Chukchi Sea, the iPOC contribution was similar between males and females, yet higher in juveniles than in adults. Despite differences in the origin of organic carbon fueling the system (sea ice versus pelagic derived carbon), the trophic position of adult female Pacific walruses was similar between the NBS and Chukchi Sea (3.2 and 3.5, respectively), supporting similar diets (i.e. clams). Given the higher quality of organic carbon from ice algae, the retreat of seasonal sea ice in recent decades may create an additional vulnerability for female and juvenile Pacific walruses and should be considered in management of the species.

Pacific walrus diet across 4000 years of changing sea ice conditions

2019 ◽  
pp. 1-17 ◽  
Author(s):  
Casey T. Clark ◽  
Lara Horstmann ◽  
Anne de Vernal ◽  
Anne M. Jensen ◽  
Nicole Misarti
Keyword(s):  
Sea Ice ◽  
Chukchi Sea ◽  
Trophic Position ◽  
Bone Collagen ◽  
Pacific Walrus ◽  
Odobenus Rosmarus Divergens ◽  
Odobenus Rosmarus ◽  
Trophic Changes ◽  
Primary Driver ◽  
Ice Conditions

AbstractDeclining sea ice is expected to change the Arctic's physical and biological systems in ways that are difficult to predict. This study used stable isotope compositions (δ13C and δ15N) of archaeological, historic, and modern Pacific walrus (Odobenus rosmarus divergens) bone collagen to investigate the impacts of changing sea ice conditions on walrus diet during the last ~4000 yr. An index of past sea ice conditions was generated using dinocyst-based reconstructions from three locations in the northeastern Chukchi Sea. Archaeological walrus samples were assigned to intervals of high and low sea ice, and δ13C and δ15N were compared across ice states. Mean δ13C and δ15N values were similar for archaeological walruses from intervals of high and low sea ice; however, variability among walruses was greater during low-ice intervals, possibly indicating decreased availability of preferred prey. Overall, sea ice conditions were not a primary driver of changes in walrus diet. The diet of modern walruses was not consistent with archaeological low sea ice intervals. Rather, the low average trophic position of modern walruses (primarily driven by males), with little variability among individuals, suggests that trophic changes to this Arctic ecosystem are still underway or are unprecedented in the last ~4000 yr.

scholarly journals Observations of Annual Walrus (Odobenus rosmarus divergens) Migrations in the Nearshore Waters of the Chukotka Peninsula from 1990 to 2012

ARCTIC ◽  
2020 ◽  
Vol 73 (1) ◽  
pp. 99-113
Author(s):  
Vladimir V. Melnikov
Keyword(s):  
Marine Mammals ◽  
Chukchi Sea ◽  
Relative Number ◽  
Bering Strait ◽  
Pacific Walrus ◽  
Odobenus Rosmarus Divergens ◽  
Odobenus Rosmarus ◽  
Commercial Harvest ◽  
The Pacific ◽  
Pass Through

After the end of the commercial harvest, research regarding the Pacific walrus (Odobenus rosmarus divergens) in Russia was reduced and focused on the observation of animals at land-based haul-outs. This paper presents the long-term observations of the distribution, relative abundance, and direction of seasonal movements of walruses in the offshore waters of the Chukotka Peninsula, based on data obtained in 1990 – 2012. Observations of Pacific walruses and other marine mammals were conducted mainly from April through November, but some were conducted all year round. In some years up to 30 Native Chukotkan observers were employed at this task. Some watched from observation posts in Native villages onshore, and others from motorboats during hunting trips. These observations have shown that walruses are rare in January and February in the nearshore waters of the Chukotka Peninsula. Their numbers begin to increase in March. The northward movement of walruses begins in April, and walruses migrate from the Bering Sea to the Chukchi Sea throughout the summer months and early autumn. Based on observations from posts located directly in front of the southern Bering Strait, I conclude that 106 – 1055 walruses pass through the Bering Strait from July to September, to the northwest and north. At the haul-outs in the Gulf of Anadyr, the relative number of walruses remains stable during the summer (up to 11 000 individuals at all haul-outs in total based on observers’ estimates) and decreases only with the appearance of ice in October – November.

scholarly journals Panmixia in a sea ice-associated marine mammal: evaluating genetic structure of the Pacific walrus (Odobenus rosmarus divergens) at multiple spatial scales

2020 ◽  
Vol 101 (3) ◽  
pp. 755-765 ◽  
Author(s):  
William S Beatty ◽  
Patrick R Lemons ◽  
Suresh A Sethi ◽  
Jason P Everett ◽  
Cara J Lewis ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Sea Ice ◽  
Spatial Scales ◽  
Pacific Walrus ◽  
Ice Dynamics ◽  
Odobenus Rosmarus Divergens ◽  
Odobenus Rosmarus ◽  
The Pacific ◽  
Kin Structure ◽  
Broad Scale

Abstract The kin structure of a species at relatively fine spatial scales impacts broad-scale patterns in genetic structure at the population level. However, kin structure rarely has been elucidated for migratory marine mammals. The Pacific walrus (Odobenus rosmarus divergens) exhibits migratory behavior linked to seasonal patterns in sea ice dynamics. Consequently, information on the spatial genetic structure of the subspecies, including kin structure, could aid wildlife managers in designing future studies to evaluate the impacts of sea ice loss on the subspecies. We sampled 8,303 individual walruses over a 5-year period and used 114 single-nucleotide polymorphisms to examine both broad-scale patterns in genetic structure and fine-scale patterns in relatedness. We did not detect any evidence of genetic structure at broad spatial scales, with low FST values (≤ 0.001) across all pairs of putative aggregations. To evaluate kin structure at fine spatial scales, we defined a walrus group as a cluster of resting individuals that were less than one walrus body length apart. We found weak evidence of kin structure at fine spatial scales, with 3.72% of groups exhibiting mean relatedness values greater than expected by chance, and a significantly higher overall observed mean value of relatedness within groups than expected by chance. Thus, the high spatiotemporal variation in the distribution of resources in the Pacific Arctic environment likely has favored a gregarious social system in Pacific walruses, with unrelated animals forming temporary associations.

scholarly journals Abundance and distribution of pacific walrus Odobenus rosmarus divergens in vicinity of Cape Serdtse-Kamen in 2009-2013

2014 ◽  
Vol 179 (4) ◽  
pp. 103-112
Author(s):  
Maxim V. Chakilev ◽  
Anatoly A. Kochnev
Keyword(s):  
Chukchi Sea ◽  
River Mouth ◽  
Native People ◽  
Economic Activities ◽  
Pacific Walrus ◽  
Traditional Use ◽  
Odobenus Rosmarus Divergens ◽  
Pacific Population ◽  
Odobenus Rosmarus ◽  
The Pacific

Results of the first special research of pacific walrus Odobenus rosmarus divergens at Cape Serdtse-Kamen conducted in the 2009-2011 and 2013 are presented. The coastal haulout place looks as series of relatively isolated areas (up to 36) located alongshore about 20 km from Cape Serdtse-Kamen to the Ikalyurynveem River mouth. Initially the walruses were on the northwestern edge of the haulout place between Cape Serdtse-Kamen and Cape Sulyn but expanded southeastward with increasing of their number. In the years with early and intense ice melting, the walruses come to the area in early September, and the haulout forms to the end of the first 10-day period of this month. In conditions of late ice retreat, as in the 2013, the walruses on the whole come to Cape Serdthse-Kamen later. The maximum number of walruses in this area was observed in 2009 (about 98,000 animals) and 2010 (118,500). This is the record number of walruses ever recorded simultaneously on one coastal haulout in the species range. Almost the whole Pacific population gathers in the vicinity of Cape Serdtse-Kamen for feeding in late autumn and continues to feed there until freezing of the Chukchi Sea. In spite of obvious significance of the area at Cape Serdtse-Kamen for the pacific walrus population, there still aren’t any special measures of their protection in this part of the coast when they are ashore - the measures are definitely necessary to prevent intensive economic activities in this key for the walruses area and to save the coastal haulout for traditional use of native people.

Genetic diversity of the Pacific walrus (Odobenus rosmarus divergens) in the western part of the Chukchi Sea

2017 ◽  
Vol 53 (2) ◽  
pp. 242-251 ◽  
Author(s):  
M. V. Shitova ◽  
A. A. Kochnev ◽  
O. G. Dolnikova ◽  
N. V. Kryukova ◽  
T. V. Malinina ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Chukchi Sea ◽  
Pacific Walrus ◽  
Odobenus Rosmarus Divergens ◽  
Odobenus Rosmarus ◽  
The Pacific

scholarly journals Mating Behaviors Exhibited by a Captive Male Pacific Walrus (Odobenus rosmarus divergens)

2016 ◽  
Vol 29 ◽  
Author(s):  
Jessica M McCord ◽  
Erin E. Frick ◽  
Dianne Cameron ◽  
Stan A. Kuczaj II
Keyword(s):  
Behavioral Repertoire ◽  
Pacific Walrus ◽  
Odobenus Rosmarus Divergens ◽  
Odobenus Rosmarus ◽  
The Pacific ◽  
In The Wild ◽  
Mating Behaviors ◽  
Present Case Study ◽  
Future Management

The population of the Pacific walrus (Odobenus rosmarus divergens) is currently a topic of conservation efforts. Understanding the mating behaviors of a species can be utilized in conservation efforts to preserve the species. Little is known about the behavioral repertoire of Pacific walruses, due to their isolated Arctic habitats, with limited studies previously describing observations of walrus mating behaviors. The aim of the present case study was to observe the mating behaviors of a single captive male Pacific walrus to examine overall frequency of specific mating behaviors in both social and solitary contexts. The subjects, one male and two females, were recorded at Six Flags Discovery Kingdom from November 2013 through January 2014. Only behaviors exhibited by the male walrus directly associated with mating were noted. Grabs were the most frequently observed behavior, and holds were not significantly observed which could contribute to the infrequent successful copulation attempts. Pharyngeal sac inflation, a vocal and visual behavior, was not frequently observed in a sexual context but has been observed in mating contexts in the wild. The male walrus used other sexual outlets such as self-gratification and toy use; however, these behaviors occurred significantly less than sexual encounters with females. There appeared to be a mate preference for the female with tusks, as the male interacted significantly more with the tusked female compared to the non-tusked female who was in estrus. Studying mating behavior in controlled settings such as this can be revealing of the capabilities of the species as a whole. Understanding more about how walruses interact in their environment can be used for future management and breeding strategies.

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