1. Quantifying the diet composition of apex marine predators such as killer whales (Orcinus orca) is critical to assessing their food web impacts. Yet, with few exceptions, the feeding ecology of ...these apex predators remains poorly understood.
2. Here, we use our newly validated quantitative fatty acid signature analysis (QFASA) approach on nearly 200 killer whales and over 900 potential prey to model their diets across the 5000 km span of the North Atlantic.
3. Diet estimates show that killer whales mainly consume other whales in the western North Atlantic (Canadian Arctic, Eastern Canada), seals in the mid-North Atlantic (Greenland), and fish in the eastern North Atlantic (Iceland, Faroe Islands, Norway). Nonetheless, diet estimates also varied widely among individuals within most regions. This level of inter-individual feeding variation should be considered for future ecological studies focusing on killer whales in the North Atlantic and other oceans.
4. These estimates reveal remarkable population- and individual-level variation in the trophic ecology of these killer whales, which can help to assess how their predation impacts community and ecosystem dynamics in changing North Atlantic marine ecosystems.
5. This new approach provides researchers with an invaluable tool to study the feeding ecology of oceanic top predators.
Determining the proportion of males and females in zooarchaeological assemblages can be used to reconstruct the diversity and severity of past anthropogenic impacts on animal populations, and can ...also provide valuable biological insights into past animal life-histories, behaviour and demography, including the effects of environmental change. However, such inferences have often not been possible due to the fragmented nature of the zooarchaeological record and a lack of clear diagnostic skeletal markers. In this study, we test whether the dog (Canis lupus familiaris) nuclear genome is suitable for genetic sex identification in pinnipeds. We initially tested 72 contemporary ringed seal (Pusa hispida) genomes with known sex, using the proportion of X chromosome DNA reads to chromosome 1 DNA reads (i.e. chrX/chr1-ratio) to distinguish males from females. This method was found to be highly reliable, with the ratios clustering in two clearly distinguishable sex groups, allowing 69 of the 72 individuals to be correctly identified according to sex. Secondly, to determine the lower limit of DNA reads required for this method, a subset of the ringed seal genome data was randomly down-sampled. We found a lower threshold of as few as 5000 mapped DNA sequence reads required for reliable sex identification. Finally, applying this standard, sex identification was successfully carried out on a broad set of ancient pinniped samples, including walruses (Odobenus rosmarus), grey seals (Halichoerus grypus) and harp seals (Pagophilus groenlandicus). All three species showed clearly distinct male and female chrX/chr1 ratio groups, providing sex identification of 42–98% of the samples, depending on species and sample quality. The approach described in this study should aid in untangling the putative effects of human activities and environmental change on populations of pinnipeds and other animal species.
•Sex identification of pinnipeds is possible using the dog genome.•ChrX/chr1 ratios defined by the dog genome was used for sex identification.•Downsampling tests suggests lower total read limit for reliable sex identification.•Sex identification was possible for 56% of all of our ancient pinniped samples.
Environmental change and increasing levels of human activity are threats to marine mammals in the Arctic. Identifying marine mammal hotspots and areas of high species richness are essential to help ...guide management and conservation efforts. Herein, space use based on biotelemetric tracking devices deployed on 13 species (ringed seal Pusa hispida, bearded seal Erignathus barbatus, harbour seal Phoca vitulina, walrus Odobenus rosmarus, harp seal Pagophilus groenlandicus, hooded seal Cystophora cristata, polar bear Ursus maritimus, bowhead whale Balaena mysticetus, narwhal Monodon monoceros, white whale Delphinapterus leucas, blue whale Balaenoptera musculus, fin whale Balaenoptera physalus and humpback whale Megaptera novaeangliae; total = 585 individuals) in the Greenland and northern Barents Seas between 2005 and 2018 is reported. Getis-Ord Gi* hotspots were calculated for each species as well as all species combined, and areas of high species richness were identified for summer/autumn (Jun-Dec), winter/spring (Jan-May) and the entire year. The marginal ice zone (MIZ) of the Greenland Sea and northern Barents Sea, the waters surrounding the Svalbard Archipelago and a few Northeast Greenland coastal sites were identified as key marine mammal hotspots and areas of high species richness in this region. Individual hotspots identified areas important for most of the tagged animals, such as common resting, nursing, moulting and foraging areas. Location hotspots identified areas heavily used by segments of the tagged populations, including denning areas for polar bears and foraging areas. The hotspots identified herein are also important habitats for seabirds and fishes, and thus conservation and management measures targeting these regions would benefit multiple groups of Arctic animals.
There has been a considerable number of reports on Hg concentrations in Arctic mammals since the last Arctic Monitoring and Assessment Programme (AMAP) effort to review biological effects of the ...exposure to mercury (Hg) in Arctic biota in 2010 and 2018. Here, we provide an update on the state of the knowledge of health risk associated with Hg concentrations in Arctic marine and terrestrial mammal species. Using available population-specific data post-2000, our ultimate goal is to provide an updated evidence-based estimate of the risk for adverse health effects from Hg exposure in Arctic mammal species at the individual and population level. Tissue residues of Hg in 13 species across the Arctic were classified into five risk categories (from No risk to Severe risk) based on critical tissue concentrations derived from experimental studies on harp seals and mink. Exposure to Hg lead to low or no risk for health effects in most populations of marine and terrestrial mammals, however, subpopulations of polar bears, pilot whales, narwhals, beluga and hooded seals are highly exposed in geographic hotspots raising concern for Hg-induced toxicological effects. About 6% of a total of 3500 individuals, across different marine mammal species, age groups and regions, are at high or severe risk of health effects from Hg exposure. The corresponding figure for the 12 terrestrial species, regions and age groups was as low as 0.3% of a total of 731 individuals analyzed for their Hg loads. Temporal analyses indicated that the proportion of polar bears at low or moderate risk has increased in East/West Greenland and Western Hudson Bay, respectively. However, there remain numerous knowledge gaps to improve risk assessments of Hg exposure in Arctic mammalian species, including the establishment of improved concentration thresholds and upscaling to the assessment of population-level effects.
The presence of grey seals has never before been confirmed in Greenland, but on 30 August 2009 a grey seal was photographed near shore in Southeast Greenland (59°53' N, 43°28' W). The seal was ...observed within a small group of islands that hosts a harbour seal colony. The following day, a seal that might be a young grey seal was photographed at the same location. Information from Inuit hunters suggests that grey seals periodically visit Greenland, but the pictures taken in summer 2009 are the first solid proof of this seal species in Greenland. RÉSUMÉ. La présence de phoques gris n'avait jamais été confirmée au Groenland, mais le 30 août 2009, un phoque gris a été photographié près de la côte sud-est du Groenland (59?53? N, 43?28? O). Le phoque a été observé au sein d'un petit groupement d'Îles où se tient une colonie de phoques communs. Le lendemain, un phoque qui était peut-être un jeune phoque gris a été photographié au même endroit. D'après les chasseurs inuits, les phoques gris se rendraient périodiquement au Groenland, mais les photographies prises à l'été 2009 constituent les premières preuves tangibles de la présence de cette espèce de phoque au Groenland. Although the observations described above might be valid, authors who were Robert Brown's contemporaries do not mention grey seals when describing the Greenlandic fauna. H.J. Rink was a scientist and inspector of the colonies in southwest Greenland and lived in Greenland from 1853 to 1868. In his book about the people living in Greenland (Rink, 1877), he thoroughly described species hunted by the Inuit, but he never mentioned grey seals. Winge (1902) reviewed all the available literature about mammals in Greenland up until the start of the 20th century, including information from Brown (1868), but he did not include the grey seal as part of Greenland's fauna. Apparently Brown had not convinced Winge of the existence of grey seals in Greenland, and none of the successive authors that have described Greenland's fauna have included the grey seal.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Aim: Identify hotspots and areas of high species richness for Arctic marine mammals. Location: Circumpolar Arctic. Methods: A total of 2115 biologging devices were deployed on marine mammals from 13 ...species in the Arctic from 2005 to 2019. Getis-Ord Gi* hotspots were calculated based on the number of individuals in grid cells for each species and for phyloge-netic groups (nine pinnipeds, three cetaceans, all species) and areas with high spe-cies richness were identified for summer (Jun-Nov), winter (Dec-May) and the entire year. Seasonal habitat differences among species’ hotspots were investigated using Principal Component Analysis. Results: Hotspots and areas with high species richness occurred within the Arctic continental-shelf seas and within the marginal ice zone, particularly in the “Arctic gateways” of the north Atlantic and Pacific oceans. Summer hotspots were generally found further north than winter hotspots, but there were exceptions to this pattern, including bowhead whales in the Greenland-Barents Seas and species with coastal distributions in Svalbard, Norway and East Greenland. Areas with high species rich-ness generally overlapped high-density hotspots. Large regional and seasonal dif-ferences in habitat features of hotspots were found among species but also within species from different regions. Gap analysis (discrepancy between hotspots and IUCN ranges) identified species and regions where more research is required. Main conclusions: This study identified important areas (and habitat types) for Arctic marine mammals using available biotelemetry data. The results herein serve as a benchmark to measure future distributional shifts. Expanded monitoring and teleme-try studies are needed on Arctic species to understand the impacts of climate change and concomitant ecosystem changes (synergistic effects of multiple stressors). While efforts should be made to fill knowledge gaps, including regional gaps and more com-plete sex and age coverage, hotspots identified herein can inform management ef-forts to mitigate the impacts of human activities and ecological changes, including creation of protected areas.
Abstract
The distribution of terrestrial surface runoff to Ilulissat Icefjord, west Greenland, is simulated for the period 2009–13 to better emphasize the spatiotemporal variability in freshwater ...flux and the link between runoff spikes and observed hydrographic conditions at the Greenland Ice Sheet tidewater glacier margins. Runoff model simulations were forced with automatic weather station data and verified against snow water equivalent depth, equilibrium line altitude, and quasi-continuous salinity and temperature observations obtained by ringed seals. Instrumented seals provide a novel platform to examine the otherwise inaccessible waters beneath the dense ice mélange within the first 0–10 km of the calving front. The estimated mean freshwater flux from land was 70.6 ± 4.2 km
3
yr
−1
, with an 85% contribution of ice discharge from Jakobshavn Isbrae (also known as Sermeq Kujalleq), 14% from runoff, and the remaining 1% from precipitation on the fjord surface area, subglacial geothermal melting, and frictional melting due to basal ice motion. Runoff was simulated to be present from May to November and to vary spatially according to glacier cover and individual catchment size. Salinity and temperature observations correlate (significantly) with simulated runoff for the upper part of both the main fjord and southern fjord arm. Also, at the tidewater glacier margins in the northern and southern arm of Ilulissat Icefjord, salinity changes in the upper water column (upper 50 m) are significant after temporal spikes in runoff during late summer, while small-amplitude runoff variability during the recession of runoff did not create a clear signal in observed salinity variability. Also, in the southern arm near the glacier margin (between 100- and 150-m depth), the heterogeneous distribution in salinity could be because of the mixing of meltwater going upward from passing the grounding line. The effect of runoff spikes on observed salinity is less pronounced near the ice margin of Jakobshavn Isbrae than in the north and south arms.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
Andersen, J. M., Wiersma, Y. F., Stenson, G. B., Hammill, M. O., Rosing-Asvid, A., and Skern-Maurizen, M. 2013. Habitat selection by hooded seals (Cystophora cristata) in the Northwest ...Atlantic Ocean. – ICES Journal of Marine Science, 70:173–185. We examined annual habitat use for 65 hooded seals (32 adult females, 17 adult males, and 16 juveniles) equipped with satellite relay data loggers (SRDLs) in spring or summer during five field seasons (2004–2008). A combined approach using first passage time (FPT) analysis and a generalized additive model (GAM) was applied to test for habitat selection, with a focus on environmental parameters of depth, slope, ice, sea surface temperature (SST), and chlorophyll. The models were run on adult males, adult females, and juveniles separately, and the results identified SST, depth, and chlorophyll as the most important factors influencing habitat selection across all categories. Furthermore, males and females preferred similar habitat conditions, but were separated geographically, and by depth, at various times of the year. Males appeared to be more localized in their habitat use patterns, focusing their search effort in areas of complex seabed relief such as Baffin Bay, Davis Strait, and the Flemish cap, while females concentrated their search effort along shelf areas (e.g. the Labrador shelf). These findings support our hypothesis that hooded seals prefer areas where topography and oceanographic processes create favourable foraging conditions.
Recent studies have shown that the complementary analysis of mercury (Hg) concentrations and stable isotopic ratios of nitrogen (δ
15
N) and carbon (δ
13
C) can be useful for investigating the ...trophic influence on the Hg exposure and accumulation in marine top predators. In this study, we propose to evaluate the interspecies variability of Hg concentrations in phocids from polar areas and to compare Hg bioaccumulation between both hemispheres. Mercury concentrations, δ
15
N and δ
13
C were measured in fur from 85 individuals representing 7 phocidae species, a Ross seal (
Ommatophoca rossii
), Weddell seals (
Leptonychotes weddellii
), crabeater seals (
Lobodon carcinophagus
), harbour seals (
Phoca vitulina
), grey seals (
Halichoerus grypus
), ringed seals (
Pusa hispida
) and a bearded seal (
Erignathus barbatus
), from Greenland, Denmark and Antarctica. Our results showed a positive correlation between Hg concentrations and δ
15
N values among all individuals. Seals from the Northern ecosystems displayed greater Hg concentrations, δ
15
N and δ
13
C values than those from the Southern waters. Those geographical differences in Hg and stable isotopes values were likely due to higher environmental Hg concentrations and somewhat greater number of steps in Arctic food webs. Moreover, dissimilarities in feeding habits among species were shown through δ
15
N and δ
13
C analysis, resulting in an important interspecific variation in fur Hg concentrations. A trophic segregation was observed between crabeater seals and the other species, resulting from the very specific diet of krill of this species and leading to the lowest observed Hg concentrations.
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