| 1. |
- Liu, X. D., et al.
(författare)
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Origin and expansion of the world's most widespread pinniped: Range-wide population genomics of the harbour seal (Phoca vitulina)
- 2022
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Ingår i: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 31:6, s. 1682-1699
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Tidskriftsartikel (refereegranskat)abstract
- The harbour seal (Phoca vitulina) is the most widely distributed pinniped, occupying a wide variety of habitats and climatic zones across the Northern Hemisphere. Intriguingly, the harbour seal is also one of the most philopatric seals, raising questions as to how it colonized its current range. To shed light on the origin, remarkable range expansion, population structure and genetic diversity of this species, we used genotyping-by-sequencing to analyse similar to 13,500 biallelic single nucleotide polymorphisms from 286 individuals sampled from 22 localities across the species' range. Our results point to a Northeast Pacific origin of the harbour seal, colonization of the North Atlantic via the Canadian Arctic, and subsequent stepping-stone range expansions across the North Atlantic from North America to Europe, accompanied by a successive loss of genetic diversity. Our analyses further revealed a deep divergence between modern North Pacific and North Atlantic harbour seals, with finer-scale genetic structure at regional and local scales consistent with strong philopatry. The study provides new insights into the harbour seal's remarkable ability to colonize and adapt to a wide range of habitats. Furthermore, it has implications for current harbour seal subspecies delineations and highlights the need for international and national red lists and management plans to ensure the protection of genetically and demographically isolated populations.
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| 2. |
- Unger, B., et al.
(författare)
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MiniSCANS-II: Aerial survey for harbour porpoises in the western Baltic Sea, Belt Sea, the Sound and Kattegat in 2020 : Joint survey by Denmark, Germany and Sweden. Final report to Danish Environmental Protection Agency, German Federal Agency for Nature Conservation and Swedish Agency for Marine and Water Management.
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The Marine Strategy Framework Directive (MSFD) (Directive 2008/56/EC) emphasises the need for cross-border monitoring of wide-ranging species, such as the harbour porpoise (Phocoena phocoena), the most abundant cetacean species occurring year-round in the Baltic Sea. In June and July 2020, Germany, Denmark, and Sweden conducted a dedicated large-scale aerial survey (called MiniSCANS-II) for harbour porpoises in the management area of the Belt Sea population, i.e., between an east-west line between Denmark and Sweden at 56.95°N in the Kattegat Sea, and a north-south line between Sweden and Germany at 13.5°E in the southern Baltic Sea. This survey followed line-transect distance sampling methodology according to the SCANS protocol to derive an unbiased absolute abundance estimate. With a realised effort of 4,533 km in nine strata, the observers recorded a total of 202 sightings (251 individuals, of these 16 were calves). The large majority of survey effort (91.2%) was conducted in either good or moderate sighting conditions. The abundance of the Belt Sea population was estimated to be 17,301 harbour porpoises (95% CI = 11,695-25,688; CV = 0.20), with an average density of 0.41 individuals/km² (95% CI = 0.28-0.61). This is the lowest abundance estimate since the first (SCANS) survey was conducted in 1994. However, the variance (especially of the earlier abundance estimates) is high, and a dedicated trend analysis needs to be conducted to determine if there has been a decline in the population abundance over time. The results should raise some concern about the status of the population and emphasise the importance of repeated surveys in the near future to increase the time series of robust abundance estimates available. Such time series are essential for monitoring the progress of the population towards achieving favourable conservation status under the Habitats Directive and good environmental status (GES) as demanded by the MSFD.
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| 3. |
- Amundin, Mats, et al.
(författare)
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Estimating the abundance of the critically endangered Baltic Proper harbour porpoise (Phocoena phocoena) population using passive acoustic monitoring
- 2022
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 12:2
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Tidskriftsartikel (refereegranskat)abstract
- Knowing the abundance of a population is a crucial component to assess its conservationstatus and develop effective conservation plans. For most cetaceans, abundanceestimation is difficult given their cryptic and mobile nature, especially when thepopulation is small and has a transnational distribution. In the Baltic Sea, the numberof harbour porpoises (Phocoena phocoena) has collapsed since the mid-20thcenturyand the Baltic Proper harbour porpoise is listed as Critically Endangered by the IUCNand HELCOM; however, its abundance remains unknown. Here, one of the largestever passive acoustic monitoring studies was carried out by eight Baltic Sea nationsto estimate the abundance of the Baltic Proper harbour porpoise for the first time. Bylogging porpoise echolocation signals at 298 stations during May 2011–April2013,calibrating the loggers’ spatial detection performance at sea, and measuring the clickrate of tagged individuals, we estimated an abundance of 71–1105individuals (95% CI,point estimate 491) during May–Octoberwithin the population's proposed managementborder. The small abundance estimate strongly supports that the Baltic Properharbour porpoise is facing an extremely high risk of extinction, and highlights theneed for immediate and efficient conservation actions through international cooperation.It also provides a starting point in monitoring the trend of the populationabundance to evaluate the effectiveness of management measures and determine itsinteractions with the larger neighboring Belt Sea population. Further, we offer evidencethat design-basedpassive acoustic monitoring can generate reliable estimatesof the abundance of rare and cryptic animal populations across large spatial scales.
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| 4. |
- Khairy, M., et al.
(författare)
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Bioaccumulation of PCBs, OCPs and PBDEs in Marine Mammals From West Antarctica
- 2021
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Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- To understand the bioaccumulation and food web dynamics of persistent organic pollutants (POPs) as a function of species, age and sex in Antarctic mammals, blubber samples of 3 killer whales (Type C) and 77 pinnipeds (Weddell, Ross and crabeater seals) were collected from the Southern Ocean, Antarctica. They were analyzed for polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs). sigma DDTs, sigma(29)PCBs and chlordanes (12 - 4,600, 13 - 1,600, and < 1.5 - 1,700 ng/g lipid, respectively) were the most abundant POPs. Killer whales typically displayed several times greater concentrations of POPs compared to seals, except for PBDEs. PCBs and PBDEs were consistently higher in adult crabeater and Weddell seal males, and in adult female Ross seals than in other sex and age groups reflecting an age accumulation and possible influence of segregated diet, foraging areas, and metabolic transformation rates. POPs concentrations significantly correlated with gene transcription of nuclear receptors involved in detoxification of contaminants and immune relevant cell mediators in the crabeater seals, indicating possible immunotoxic and deleterious health effects. This represents one of the largest studies on POPs in Antarctic marine predators and highlights the complexity of POPs bioaccumulation.
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