Circumpolar Distribution Research Articles

Gyrfalcon Disease Ecology: A Survey Across Western Alaska

ABSTRACT The Gyrfalcon (Falco rusticolus) is a top avian predator, an Arctic specialist, and among the bird species most vulnerable to climate change. This vulnerability is driven by their narrow ecological niche, limited or lack of southward migration, and circumpolar distribution where the most rapid climatic changes are occurring. Climatic and habitat changes may alter Gyrfalcon disease ecology due to changes in vector distributions, host ranges, and pathogen life cycles. Warmer Arctic temperatures and accompanying landscape changes may also alter the Gyrfalcon’s prey base, and dietary habits can influence transmission of pathogens. To better understand disease ecology in Gyrfalcons, we compared pathogen prevalence across varying time periods at three study sites in Alaska—the Seward Peninsula (2014–2022), the Alaska Peninsula (2021–2022), and the Yukon–Kuskokwim Delta (2008–2013). We collected Gyrfalcon whole blood, thin blood films, cloacal swabs, and fecal samples for serology, haemoparasite assays, microbiological cultures, and fecal tests for parasites. An aliquot of whole blood preserved on filter paper or in Longmire solution was kept for molecular diagnosis of haemoparasites. Serology revealed high exposure to Salmonella (77%), low seroprevalence of avian influenza antibodies (1.5%), exposure to falcon adenovirus type 1 in hatch-year Gyrfalcons (1.3%), and the first report of a Leucocytozoon spp. blood parasite in a Gyrfalcon. We found no antibodies indicative of prior exposure to avian paramyxovirus, West Nile virus, or Chlamydia. One nestling and one hatch-year bird sampled (2 of 12) on the Seward Peninsula exhibited oral plaques from capillarids (Eucoelus spp.) in contrast to those trapped in the Izembek National Wildlife Refuge on the Alaska Peninsula (0 of 6).

Inferences about the population history of Rangifer tarandus from Y chromosome and mtDNA phylogenies.

Reindeer, called caribou in North America, has a circumpolar distribution and all extant populations belong to the same species (Rangifer tarandus). It has survived the Holocene thanks to its immense adaptability and successful coexistence with humans in different forms of hunting and herding cultures. Here, we examine the paternal and maternal history of Rangifer based on robust Y-chromosomal and mitochondrial DNA (mtDNA) trees representing Eurasian tundra reindeer, Finnish forest reindeer, Svalbard reindeer, Alaska tundra caribou, and woodland caribou. We first assembled Y-chromosomal contigs, representing 1.3 Mb of single-copy Y regions. Based on 545 Y-chromosomal and 458 mtDNA SNPs defined in 55 males, maximum parsimony trees were created. We observed two well separated clades in both phylogenies: the "EuroBeringian clade" formed by animals from Arctic Islands, Eurasia, and a few from North America and the "North American clade" formed only by caribou from North America. The time calibrated Y tree revealed an expansion and dispersal of lineages across continents after the Last Glacial Maximum. We show for the first time unique paternal lineages in Svalbard reindeer and Finnish forest reindeer and reveal a circumscribed Y haplogroup in Fennoscandian tundra reindeer. The Y chromosome in domesticated reindeer is markedly diverse indicating that several male lineages have undergone domestication and less intensive selection on males. This study places R. tarandus onto the list of species with resolved Y and mtDNA phylogenies and builds the basis for studies of the distribution and origin of paternal and maternal lineages in the future.

Archaeological evidence of resource utilisation of walrus, Odobenus rosmarus, over the past two millennia: A systematic review protocol.

The walrus, Odobenus rosmarus, is an iconic pinniped and predominant molluscivore that is well adapted to Arctic and subarctic environments. Its circumpolar distribution, large body size and ivory tusks facilitated its vital role as food, raw material (for tools and art), income, and cultural influence on many Arctic Indigenous communities for millennia. Intensification of hunting (often due to the arrival of Europeans, especially between the 16 th and 19 th centuries) to obtain ivory, hide, blubber and meat, resulted in diminished, sometimes extirpated, walrus populations. Zooarchaeological, artefactual and documentary evidence of walrus material has been collated at local and regional scales and is frequently focused on a specific culture or period of time. Systematic collation of this evidence across the Northern Hemisphere will provide insight into the chronology and circumpolar distribution of walrus hunting and provide a tool to document societal change in walrus resource use. Here, we lay out a systematic review protocol to collate records of archaeological walrus artefacts, tusks and bones that have been documented primarily within published literature to archive when and where (as feasible) walrus extractions occurred between 1 CE and 2000 CE. These data will be openly available for the scientific community. The resulting dataset will be the first to provide spatiotemporal information (including the recognition of knowledge gaps) regarding past walrus populations and extirpations on a circumpolar scale. Our protocol is published to ensure reproducibility and comparability in the future, and to encourage the adoption of systematic review methodology (including pre-published protocols) in archaeology.

Mitochondrial DNA structuring of Antarctic prions (Pachyptila desolata, Procellariidae)

Prions (Pachyptila) are small seabirds with a Southern Hemisphere breeding distribution. Antarctic prion (Pachyptila desolata) and Salvin’s prion (P. salvini) are two species that are regularly recorded in New Zealand as beach-wrecks but they are difficult to distinguish morphologically. Salvin’s prion is restricted to breeding on the Prince Edward Islands and Crozet Islands in the Indian Ocean but Antarctic prions have a circumpolar breeding distribution on numerous sub-Antarctic and Antarctic islands in the Southern, South Atlantic and Indian Oceans. Our aim was to examine the level of mitochondrial DNA (mtDNA) structuring within Antarctic prion and Salvin’s prion colonies, to test whether this technique can determine the provenance of beach-cast birds. The Auckland Islands Antarctic prion population exhibited distinct mtDNA haplotypes from all other populations, supporting the suggestion that these islands may have been an ice-free refugium during the Last Glacial Maximum. All other sampled breeding populations shared haplotypes, limiting the use of these sequences for determining the provenance of beach-cast birds. None of our museum specimens of Salvin’s prion collected from breeding colonies produced DNA sequences. This result indicates that the method by which these specimens, which were collected in the 1960s and 70s, were preserved, or subsequent treatments, has resulted in the loss of their DNA.

Multiplexing PCR allows the identification of within-species genetic diversity in ancient eDNA.

Sedimentary ancient DNA (sedaDNA) has rarely been used to obtain population-level data due to either a lack of taxonomic resolution for the molecular method used, limitations in the reference material or inefficient methods. Here, we present the potential of multiplexing different PCR primers to retrieve population-level genetic data from sedaDNA samples. Vaccinium uliginosum (Ericaceae) is a widespread species with a circumpolar distribution and three lineages in present-day populations. We searched 18 plastid genomes for intraspecific variable regions and developed 61 primer sets to target these. Initial multiplex PCR testing resulted in a final set of 38 primer sets. These primer sets were used to analyse 20 lake sedaDNA samples (11,200 cal. yr BP to present) from five different localities in northern Norway, the Alps and the Polar Urals. All known V. uliginosum lineages in these regions and all primer sets could be recovered from the sedaDNA data. For each sample on average 28.1 primer sets, representing 34.15 sequence variants, were recovered. All sediment samples were dominated by a single lineage, except three Alpine samples which had co-occurrence of two different lineages. Furthermore, lineage turnover was observed in the Alps and northern Norway, suggesting that present-day phylogeographical studies may overlook past genetic patterns. Multiplexing primer is a promising tool for generating population-level genetic information from sedaDNA. The relatively simple method, combined with high sensitivity, provides a scalable method which will allow researchers to track populations through time and space using environmental DNA.

Chukotka as a Portal for the Rabies Introduction into Kamchatka (Systematic Review)

The aim of this review was to assess the peculiarities of distribution and epidemiological risk of rabies in the extreme northeast of Asia. The systematic review was prepared through synthesizing publications on rabies over 1860–2022 (n=22) and previously unpublished data for 2009–2023. From the late 19th century until the 1980s, rabies epizootics were consistently observed in Chukotka and Kamchatka. A correlation was found between the time of occurrence of rabies in those territories with a lag period of 1–2 years (r=0.349; p=0.054). In 2009–2023, 24 animal rabies cases were confirmed in Chukotka; rabies has not been registered in Kamchatka since 1981. Until 1982, 5 confirmed human rabies cases were described in Chukotka, as well as 4 lethal cases presumably due to rabies (Chukotka – 3, Kamchatka – 1). The similarity of the spatial distribution of epizootics in different periods of time was established. Rabies was detected mainly in the area of the permanent polar fox (Vulpes lagopus) habitation, in the coastal tundra from the mouth of the Kolyma River to the Anadyr Gulf. Outside this territory (the valleys of the Anadyr and Penzhina Rivers, the Kamchatka Peninsula), rabies was reported in red foxes (Vulpes vulpes). At present, the importance of the polar fox in the spread of rabies in Chukotka has decreased, while the significance of the red fox has increased substantially. Due to vaccination, rabies among dogs is recorded sporadically. Rabies virus isolates from Chukotka belong to the Arctic genetic lineage (Arctic-3 group), which has a circumpolar distribution. The possibility of independent circulation of the rabies virus in the Kamchatka Peninsula is doubtful because of the limited size of the red fox population. Based on the mapping, possible directions for the introduction of rabies to Kamchatka from Chukotka have been identified. Barrier oral rabies vaccination of foxes is recommended during the years of high abundance of red and polar foxes in Chukotka.

Connectivity of Greenland halibut in the northwestern Atlantic Ocean inferred from otolith chemistry

Greenland Halibut (Reinhardtius hippoglossoides) is a deepwater flatfish having a circumpolar distribution. Understanding the spatial connectivity and migratory patterns of this commercially valuable species is essential for ensuring a sustainable fishery; nonetheless, this information remains relatively scarce for many Greenland Halibut populations. Here we evaluate the connectivity and the population structure of halibut along coastal Greenland and Canada to better characterize the contribution of each production zone to the various stocks found in the northwestern Atlantic Ocean. In 2014 and 2016, we sampled 411 large Greenland Halibut from coastal Nunavut, Labrador, and Greenland. We used the elemental fingerprint (magnesium, strontium, and barium) from the otolith core and margin of the sampled fish to determine spatial differentiation of the source areas of the collected halibut. From the 17 sample sites, margin elemental fingerprint delineated four “elemental sectors”, representing pooled adjacent sites having similar chemistry. Overall, 62% of Greenland Halibut were correctly assigned to their sampled coast. Elemental fingerprint of the otolith cores indicated three chemically distinct natal sources for the captured halibut. The chemical record in the otolith cores suggested a high connectivity of Greenland Halibut in the northwestern Atlantic and a main natal source located potentially along the west coast of Greenland. Given that our results suggest the presence of a large nursery around Disko Bay–Hellefiske Bank, protection measures should be considered for this area.

A SHORT NOTE ON WATER QUALITY AND SOME BIODIVERSITY COMPONENTS IN GURBAN VALLEY, GIURGIU COUNTY

Several field trips were carried out in 2022 and 2023, aiming to investigate the water quality parameters, ichthyofaunal and floristic diversity in some areas of Gurban Valley, located in the protected area Natural Park Comana, Giurgiu County, southern Romania. Throughout the study period were identified fish specimens belonging to nine species: Prussian carp Carassius gibelio (Bloch, 1782); Gobio obtusirostris Valenciennes, 1842; Dnieper chub Petroleuciscus borysthenicus (Kessler, 1859); Roach Rutilus rutilus (Linnaeus, 1758); Danubian spined loach Cobitis elongatoides Băcescu & Mayer, 1969; Belica Leucaspius delineatus (Heckel, 1843); Southern ninespine stickleback Pungitius platygaster (Kessler, 1859); European bitterling Rhodeus amarus (Bloch, 1782) and European mudminnow Umbra krameri Walbaum, 1792. A total of 147 captured specimens were measured, weighed and photographed. For the capture of fish, minnow traps and plankton nets were used, on the Gurban River, right tributary of the Neajlov River, Giurgiu County. The floristic inventory compiled so far included 58 plant species grouped into 31 families, with European, circumpolar, Eurasian, eurasiatic continental or cosmopolitan distribution. Related to physico-chemical characterization of water samples collected from four sampling points (SP), the results of laboratory analysis allowed to frame the water into quality classes and to evaluate if the water meets the requirements for aquatic organisms. Hence, on the basis of nitrite-nitrogen (N-NO2-) and nitrate-nitrogen (N-NO3-) water corresponds to Ist quality class, meanwhile chemical oxygen demand (COD), phosphate-phosphorus (P-PO43-) and ammonium-nitrogen (N-NH4+) allowed to associate water quality with IIIrd class. In addition, it has been found very significant correlations between electrical conductivity (EC) and total hardness (TH) with r=0.9230*** and between pH and TH with r=0.8821***, respectively.

A taxonomic revision of Australian Cenozoic Cassidae and Tonnidae species (Mollusca, Gastropoda)

Fifteen species of Cassidae, of which three are new, and one species of Tonnidae are recognized from the Cenozoic deposits of southern Australia. These are: Cassis exigua (incorporating the synonyms Cassis textilis, Cassis contusus, Cassis salisburyensis, and probably Cassis nana), Cassis fimbriata; Echinophoria statioliteralis sp. nov., Echinophoria wilsoni, Echinophoria aff. Echinophoria pollens, Echinophoria trinodosa; Galeodea fuscirivularis sp. nov., Galeodea goudeyi sp. nov., Galeodea gradata; Semicassis pyrum; Antephalium sufflatum, Antephalium transennum, Antephalium radiatum, Antephalium semigranosum (including Semicassis muelleri and Semicassis subgranosa as synonyms), Antephalium adcocki; and Eudolium bairdii (synonymous with Dolium biornatum). Cassids and tonnids have a sporadic record in southern Australia from late Eocene to the present, owing to breaks in the stratigraphical record and lack of suitable facies. All the genera found fossil are known in the living fauna, but species of Echinophoria, Galeodea and Eudolium, are now confined to warmer waters of northern Australia, whereas Antephalium, which ranges from early Miocene to the present, is confined to southern Australia. Living species of Cassis and Semicassis have a circum-Australian distribution. Semicassis pyrum has a circumpolar distribution occurring also in New Zealand, South America and South Africa. Thomas A. Darragh [tdarragh@museum.vic.gov.au], Museums Victoria, GPO Box 666 Melbourne 3001, Victoria, Australia.

Circumpolar distributions of age and anthropogenic CO2 content of Antarctic Bottom Water revealed by chlorofluorocarbon and sulfur hexafluoride

Antarctic Bottom Water (AABW) sequesters anthropogenic CO2 (Cant) over the long-term and impacts the global carbon cycle. In this study, data of chlorofluorocarbon and sulfur hexafluoride observed from 2005 to 2020 in the Southern Ocean (SO) were used to investigate the age and Cant content of AABW. In the coastal regions of the Cosmonaut, Cooperation, D’Urville, and Somov Seas and near the Pacific-Antarctic Ridge, the age of AABW was < 5 years, reflecting the spread of newly formed AABW. Higher Cant inventory in AABW was detected in the Atlantic Ocean sector of the SO such as the Weddell and Lazarev Seas (29–55 ± 19–39 mol m−2) and the Cosmonaut and Cooperation Seas (35 ± 14 mol m−2) than those in the other regions. The amount of Cant in AABW in this region (7 ± 1–2 PgC) was estimated to be 78 % of the total Cant in AABW of the SO, suggesting the Atlantic Ocean sector as a major player to Cant sequestration in the abyssal ocean. The high Cant inventory in the Cosmonaut and Cooperation Seas is attributed to the presence of new AABW. The high Cant inventory also corresponded to the thick layer and high formation rate of AABW. Similar to the Cosmonaut and Cooperation Seas, the high Cant inventory in the Weddell and Lazarev Seas reflects the thick layer and high formation rate of AABW. The total amount of Cant in AABW in the SO (9 ± 1–2 PgC that would be the upper limit) was roughly estimated to be 15 % of the total Cant in the whole water column in the SO. This study highlights that AABW formation, transport, and storage processes play important roles in the total Cant sequestration in the SO.

Circumpolar assessment of mercury contamination: the Adélie penguin as a bioindicator of Antarctic marine ecosystems.

Due to its persistence and potential ecological and health impacts, mercury (Hg) is a global pollutant of major concern that may reach high concentrations even in remote polar oceans. In contrast to the Arctic Ocean, studies documenting Hg contamination in the Southern Ocean are spatially restricted and large-scale monitoring is needed. Here, we present the first circumpolar assessment of Hg contamination in Antarctic marine ecosystems. Specifically, the Adélie penguin (Pygoscelis adeliae) was used as a bioindicator species, to examine regional variation across 24 colonies distributed across the entire Antarctic continent. Mercury was measured on body feathers collected from both adults (n = 485) and chicks (n = 48) between 2005 and 2021. Because penguins' diet represents the dominant source of Hg, feather δ13C and δ15N values were measured as proxies of feeding habitat and trophic position. As expected, chicks had lower Hg concentrations (mean ± SD: 0.22 ± 0.08 μg·g‒1) than adults (0.49 ± 0.23 μg·g‒1), likely because of their shorter bioaccumulation period. In adults, spatial variation in feather Hg concentrations was driven by both trophic ecology and colony location. The highest Hg concentrations were observed in the Ross Sea, possibly because of a higher consumption of fish in the diet compared to other sites (krill-dominated diet). Such large-scale assessments are critical to assess the effectiveness of the Minamata Convention on Mercury. Owing to their circumpolar distribution and their ecological role in Antarctic marine ecosystems, Adélie penguins could be valuable bioindicators for tracking spatial and temporal trends of Hg across Antarctic waters in the future.

Apophytes in the flora of the Seymskiy Regional Landscape Park (Ukraine): analysis and list of species

The group of apophytes (native synanthropic plants) in the Seymskiy Regional Landscape Park (Sumy Oblast, northern Ukraine) has been studied with respect to its species composition and other features. This group in the park includes 285 species from 193 genera and 63 families. Among them, the most numerously represented families are the Asteraceae, Fabaceae, Caryophyllaceae, Poaceae, Scrophulariaceae, Lamiaceae, Rosaceae, Brassicaceae, Apiaceae, Polygonaceae, Boraginaceae, Cyperaceae, and Ranunculaceae, while the major genera are Trifolium, Veronica, Carex, Galium, Poa, Artemisia, Centaurea, Plantago, Potentilla, Rumex, Verbascum, and Viola. This study shows that hemicryptophytes dominate among plant life-forms, and most species are mesophytes. Meadow species of apophytes are the most numerous ecological group. The core of the group of apophytes consists of species of European-West Asian, Eurasian, European, and circumpolar distribution. According to the latitudinal types of distribution range, dominant positions are occupied by temperate-submeridional, boreal-submeridional, boreal-meridional, and temperate-meridional species. Hemiapophytes make up 41.4% of apophyte species, while accidental apophytes (38.2%), and euapophytes (20.4%) are less numerous. In the flora of the park, apophytes prevail over the adventive fraction (alien species introduced accidentally or intentionally). This contrasts with the contribution of apophytes to the flora of Ukraine and other protected areas.

A review of aerial survey density estimates of bearded seals (Erignathus barbatus) in the Canadian Arctic highlights important knowledge gaps and research needs

AbstractThere has been significant sea ice loss in the Arctic as a result of climate change, with measurable impacts on available habitat for ice-obligate marine mammals. Bearded seals (Erignathus barbatus) have a circumpolar distribution and primarily inhabit coastal areas of shallower depths with seasonal pack ice cover. However, there is limited information and no formal estimates on population abundance and densities of bearded seals within Canada. Here, we review historic field reports and publications from aerial surveys conducted from 1974 to 2022 to compile the density and abundance estimates of bearded seals across Canadian waters. Aerial surveys for marine mammals have been flown in several areas across the Canadian Arctic, including the Beaufort Sea (1974–2006), Canadian High Arctic (1979–2022), Baffin Bay-Davis Strait (1979–2014), and the Hudson Complex (1994–2017). After reviewing all published data sources, we report that the density of bearded seals in Canada were highest (and highly variable) in the Beaufort Sea (0.01–8.68 seals*km−2), then in Baffin Bay-Davis Strait (0.004–8.3 seals*km−2), and lowest and less variable inter-annually in the Hudson Complex (0.02 to 0.12 seals*km−2) at the time of these surveys. We also determined that bearded seals are more often found in areas of patchy ice cover (50–75%) with shallow water depths ≤ 500 m. Further, this review identifies regions within the Canadian Arctic and sub-Arctic that require updated aerial survey information. Quantifying the abundance and density estimates of bearded seals in Canada is essential for monitoring population status over time to better understand how this species is responding to environmental variation from anthropogenic activity and climate change.

Records of leopard seals Hydrurga leptonyx ashore in South Australia, 2017–2022

The leopard seal Hydrurga leptonyx is one of five phocid species with a circumpolar distribution in the Southern Ocean. They do not breed on the Australian coast. We document records of 14 leopard seals (two collected specimens, 12 live sightings) in South Australia (SA) between November 2017 and November 2022, from Fowlers Bay to the mouth of the River Murray. We used records from the SA Museum, reports from coastal officers of SA Department for Environment and Water, and information from the public. All 14 seals were juvenile and most were in fair/thin body condition. Two collected specimens and two sighted animals showed evidence of blunt trauma. Stomachs contained fish remains and feathers, and one contained 21 semi-digested smooth toadfish Tetractenos glaber, a species which contains the toxin tetrodotoxin. Necropsies on two specimens involved gross, histopathological, and diagnostic assessment of pathogens, organs, and skin lesions. All records were between June and December, similar to the seasonal distribution reported previously in southern Australia. The 14 records over 5 years to 2022 averaged 2.8 per year, higher than during a previous study in SA that ran over three decades to October 2009 at 1.2 per year.

Sex‐specific mercury levels in skin samples of southern elephant seals (Mirounga leonina) at Isla 25 de Mayo (King George Island), Antarctic Peninsula

AbstractThe southern elephant seal (SES; Mirounga leonina) has a circumpolar distribution, breeding mainly on sub‐Antarctic islands and making long trips between breeding or molting and foraging areas. Most individuals from colonies in the South Shetland Islands (western Antarctic Peninsula; WAP) are distributed in Antarctic Specially Protected Areas (ASPA). Despite these protected habitats, pollutants can reach such remote areas far away from emission sources, affecting local fauna. To assess possible mercury (Hg) contamination in SES, we analyzed skin samples collected from free‐ranging molting individuals using the remote biopsy PAXARMS system in Isla 25 de Mayo/King George Island (62°15′S, 58°39′W; ASPA 132). Hairless skin samples were analyzed to determine total‐Hg (THg) concentrations, which ranged between 145 ng/g and 1,915 ng/g (M = 730, SD = 388 ng/g), showing significant differences between sexes, with adult‐females having higher concentrations (range = 306–1,915, M = 859, SD = 427 ng/g dw) than subadult‐males (range = 145–1,645, M = 629, SD = 329 ng/g dw). These differences may be explained mainly by feeding‐niche partitioning between sexes. Females prefer mesopelagic prey or prey associated with sea‐ice in the WAP, which are enriched in methylmercury. These results provide insight regarding Hg contamination in top Antarctic predators like SES, and the need to monitor for potential effects of Hg contamination in Antarctic marine mammals.

KRILLPODYM: a mechanistic, spatially resolved model of Antarctic krill distribution and abundance

Robust prediction of population responses to changing environments requires the integration of factors controlling population dynamics with processes affecting distribution. This is true everywhere but especially in polar pelagic environments. Biological cycles for many polar species are synchronised to extreme seasonality, while their distributions may be influenced by both the prevailing oceanic circulation and sea-ice distribution. Antarctic krill (krill, Euphausia superba) is one such species exhibiting a complex life history that is finely tuned to the extreme seasonality of the Southern Ocean. Dependencies on the timing of optimal seasonal conditions have led to concerns over the effects of future climate on krill’s population status, particularly given the species’ important role within Southern Ocean ecosystems. Under a changing climate, established correlations between environment and species may breakdown. Developing the capacity for predicting krill responses to climate change therefore requires methods that can explicitly consider the interplay between life history, biological conditions, and transport. The Spatial Ecosystem And Population Dynamics Model (SEAPODYM) is one such framework that integrates population and general circulation modelling to simulate the spatial dynamics of key organisms. Here, we describe a modification to SEAPODYM, creating a novel model – KRILLPODYM – that generates spatially resolved estimates of krill biomass and demographics. This new model consists of three major components: (1) an age-structured population consisting of five key life stages, each with multiple age classes, which undergo age-dependent growth and mortality, (2) six key habitats that mediate the production of larvae and life stage survival, and (3) spatial dynamics driven by both the underlying circulation of ocean currents and advection of sea-ice. We present the first results of KRILLPODYM, using published deterministic functions of population processes and habitat suitability rules. Initialising from a non-informative uniform density across the Southern Ocean our model independently develops a circumpolar population distribution of krill that approximates observations. The model framework lends itself to applied experiments aimed at resolving key population parameters, life-stage specific habitat requirements, and dominant transport regimes, ultimately informing sustainable fishery management.

Quantifying circumpolar summer habitat for Antarctic krill and Ice krill, two key species of the Antarctic marine ecosystem

AbstractAntarctic krill (Euphausia superba) and Ice krill (Euphausia crystallorophias) are key species within Southern Ocean marine ecosystems. Given their importance in regional food webs, coupled with the uncertain impacts of climate change, the on-going recovery of krill-eating marine mammals, and the expanding commercial fishery for Antarctic krill, there is an increasing need to improve current estimates of their circumpolar habitat distribution. Here, we provide an estimate of the austral summer circumpolar habitat distribution of both species using an ensemble of habitat models and updated environmental covariates. Our models were able to resolve the segregated habitats of both species. We find that extensive potential habitat for Antarctic krill is mainly situated in the open ocean and concentrated in the Atlantic sector of the Southern Ocean, while Ice krill habitat was concentrated more evenly around the continent, largely over the continental shelf. Ice krill habitat was mainly predicted by surface oxygen concentration and water column temperature, while Antarctic krill was additionally characterized by mixed layer depth, distance to the continental shelf edge, and surface salinity. Our results further improve understanding about these key species, helping inform sustainable circumpolar management practices.

Estimation of total population size of southern elephant seals (Mirounga leonina) on Kerguelen and Crozet Archipelagos using very high-resolution satellite imagery

Southern elephant seals (Mirounga leonina) play a pivotal role in the Southern Ocean as wide-ranging marine predators and major prey consumers within Southern Ocean marine ecosystems. Due to their circumpolar distribution and the remoteness of their habitat, large uncertainties remain about their total population sizes. This is especially true for elephant seal populations in the French Southern Territories in the southern Indian Ocean (i.e. Crozet and Kerguelen Archipelagos) as many breeding sites are inaccessible for ground censuses. Here, we present a simple and efficient approach for estimating the total elephant seal populations of the Kerguelen and Crozet Archipelagos by using very high-resolution satellite imagery (&amp;lt;1m resolution). Twenty-eight satellite images taken during the breeding season to count female elephant seals in inaccessible areas were used and complemented the traditional annual ground counts in accessible areas. For Kerguelen Island sectors likely to host colonies and where no satellite images were available for the breeding season, a statistical predictive model was built to estimate the most likely number of breeding females to be present on a given beach according to its physiographic characteristics. Our results show the reliability of using very high-resolution satellite images, a relatively low-cost platform, to count pinniped populations and provide the first estimation of the total southern elephant seal population for both the Kerguelen 347,995 (s e = 4,950) and Crozet 13,065 (s e = 169) Archipelagos. The combined total represents over 35% of the global elephant seal population with the Kerguelen stock being numerically equivalent to the South Georgia stock. In addition, we re-examined the population trends since the last mid-century for Kerguelen and over the last five decades for Crozet. The demographic trends of the southern Indian Ocean populations show marked growth over the last decade (5.1% and 1.6% annual growth rate for Crozet and Kerguelen respectively), particularly on Crozet where the elephant seal population has more than tripled.

Will current protected areas harbor refugia for threatened Arctic vegetation types until 2050? A first assessment

ABSTRACT Arctic vegetation is crucial for fauna and the livelihoods of Northern peoples and is tightly linked to climate, permafrost soils, and water. Yet, a comprehensive understanding of climate change effects on Arctic vegetation is lacking. Protected areas cannot halt climate change but could reduce future pressure from additional drivers, like land use change and local industrial pollution. Therefore, it is crucial to understand the contribution of protected areas in safeguarding threatened Arctic vegetation types. We compare the present baseline with 2050 predictions of circumpolar Arctic vegetation type distributions and demonstrate an overrepresentation of dominant vegetation types and an underrepresentation of declining vegetation types within protected areas. Our study predicts five of eight assessed tundra vegetation types to be threatened by 2050, following International Union for Conservation of Nature criteria. Further, we mapped potential climate change refugia, areas with the highest potential for safeguarding threatened vegetation types. This study provides an essential first step assessing vegetation type vulnerability based on predictions covering 42 percent of Arctic landscapes. The co-development of new protective measures by policymakers and Indigenous peoples at a pan-Arctic scale requires more robust and spatially complete vegetation predictions, as increasing pressures from resource exploration and infrastructure development threaten the sustainable development of the rapidly thawing and greening Arctic.

Three forms of killer whales (Orcinus orca) in Antarctic waters

This paper provides field descriptions and biological observations of three different forms of killer whale (Orcinus orca) that occur in Antarctica based on field observations and a review of available photographs. Identifications were based on the relative size and orientation of the white eyepatch and the presence or absence of a dorsal cape. Type A (presumably the nominate form) has a medium-sized eyepatch oriented parallel to the body axis, no dorsal cape, it occurs mainly off-shore in ice-free water, has a circumpolar distribution and apparently preys mainly upon Antarctic minke whales (Balaenoptera bonaerensis). Type B also has an eyepatch oriented parallel to the body axis, but the eyepatch is at least twice as large as in Type A, it has a dorsal cape, mainly inhabits inshore waters, regularly occurs in pack-ice, is distributed around the continent and is regularly sighted in the Antarctic Peninsula area. Although it may also prey upon Antarctic minke whales and possibly humpback whales (Megaptera novaeangliae), seals seem to be the most important prey item. Type C has a small, forward-slanted eyepatch, a dorsal cape, inhabits inshore waters and lives mainly in the pack-ice; it occurs mostly off East Antarctica, and to date it has been recorded feeding only on Antarctic toothfish (Dissostichus mawsoni). Type C appears to be referable to Orcinus glacialis as described by Berzin and Vladimirov (1983). Although similar ecological specialisations have been reported for sympatric killer whale populations in the Northeast Pacific (i.e. an inshore mammal-eater, an inshore fish-eater and an offshore form), the extent of morphological divergence, habitat segregation and, perhaps, reproductive isolation, appears to be more pronounced among Antarctic populations. Although under a Biological Species Concept these forms appear to warrant separate species status, it will be important to show that this interpretation is consistent with results of molecular genetic analyses and additional morphological studies.