A major feeding ground for cetaceans and seabirds in the south-western Greenland Sea

In the frame of our long-term study of the distribution of seabirds and marine mammals in polar seas, observers from this team participated in the European Arctic expeditions of icebreaking RV Polarstern during summer 2008. The main aims were to obtain more information on the mechanisms underlying the at-sea distribution of the ??higher trophic levels?? and to detect possible temporal and spatial changes in numbers, especially in function of climatic changes and decreasing ice coverage in the Arctic. In total, 1,175 half-an-hour transect counts were devoted to seabird and marine mammal distribution in the Greenland and Norwegian Seas, from 14 June to 15 August, 2008. A major feeding ground for cetaceans and seabirds was detected in the south-western Greenland Sea and the Denmark Strait in the Polar Front between Polar and Arctic Water masses. For the main cetacean and seabird species, almost all individuals recorded during the whole expedition were encountered in this limited zone of 33 counts: 135 humpback whales Megaptera novaeangliae and 1,940 common guillemots Uria aalge. Moreover, 4,400 fulmars Fulmarus glacialis light morph were observed in this zone, i.e. close to half of the total. All were actively feeding, making this zone the major feeding ground for the higher trophic levels in the European Arctic Seas and so confirming the great importance of fronts (upwellings) for the biological productivity of the oceans. Such data are essential for a successful conservation and management of the Denmark Strait and adjacent areas.     

A major autumn feeding ground for fin whales, southern fulmars and grey-headed albatrosses around the South Shetland Islands, Antarctica

The main aim of our long-term study on the at-sea distribution of the upper trophic levels in polar marine ecosystems is to deepen the understanding of the basic mechanisms affecting their distribution, i.e. hydrological factors such as water masses and fronts, pack ice and ice edge, eddies. A second goal consists in detecting spatial and temporal changes, with special attention to global climate changes, as well as possible consequences of (krill) fisheries. Seabirds and marine mammals were recorded during an autumn expedition of icebreaking RV Polarstern between Punta Arenas and the South Shetland Islands, Antarctica in March/ April 2012. During a total of 333 half-an-hour transect counts without width limitation, 113,500 seabirds were encountered, belonging to 40 species. The vast majority were southern fulmars and grey-headed albatross around the South Shetland Islands, with 76,800 and 7,000 individuals, respectively. Fin whale was by far the most abundant cetacean with 300 identified individuals in the same area, of which 100 in one count. These exceptional concentrations of fin whale seem to reflect an autumn pre-migration feeding aggregation. For most species, the majority was concentrated in very few counts, reflecting a very high patchiness and, as upper trophic levels, an important prey availability—mainly krill, nekton and small fish. Low biodiversity was reflected by both the low number of species and the fact that a few species represent the vast majority in numbers. It is suggested that the area deserves future biological studies, especially in autumn, and a special protection management.     

An important late summer aggregation of fin whales Balaenoptera physalus,little auks Alle alle and Brünnich’s guillemots Uria lomvia in the eastern Greenland Sea and Fram Strait: influence of hydrographic structures

The distribution at sea of upper trophic levels—seabirds and marine mammals—is depending on their food availability: high concentrations reflect high prey abundance and thus high biological production. Polar marine ecosystems are characterized by low biodiversity and high biological patchiness. The distribution of predators, as a consequence, shows a similar patchiness. During two expeditions of icebreaking RV Polarstern in June–July 2011, biodiversity in the arctic marine zone north of 70°N was very low, with low numbers of species: 20 seabirds, eight cetaceans, five pinnipeds and polar bear. Moreover, a few species accounted for the majority in numbers: four bird species for 95 % of the total of 23,000 seabirds recorded during 700 transect counts: fulmar Fulmarus glacialis, kittiwake Rissa tridactyla, Brünnich’s guillemot Uria lomvia and little auk Alle alle. Among the marine mammals, 250 fin whales Balaenoptera physalus accounted for 80 % of the identified large cetaceans, 270 white-beaked dolphin Lagenorhynchus albirostris for 100 % of the small cetaceans and 180 harp seals Pagophilus groenlandica for 80 % of the identified pinnipeds. Their quantitative distribution was depending on water masses and oceanic fronts, large cetaceans—mainly fin whales—showing an important aggregation on the shelf slope off western Spitsbergen, as well as little auks and Brünnich’s guillemots. So that this zone, shelf slope and front of mixed Arctic/Atlantic Waters, showed unusually high seabird and cetacean concentrations. Seasonal factors possibly influencing their distribution are addressed.     

Environmental determinants of top predator distribution within the dynamic winter pack ice zone of the northern Antarctic Peninsula

Global warming is predicted to reduce the amount of sea ice concentration in polar environments, thus presenting profound changes for populations of seabirds and marine mammals dependent on sea ice. Using data from a shipboard survey during August 2012, I test the hypothesis that relative abundance of seabird and marine mammals reflects environmental variability associated with the dynamic pack ice zone. Using environmental data and observations of sea ice concentration, I quantified an environmental gradient that describes the spatial organization of the dynamic pack ice zone. The relationship of top predators to this environmental gradient revealed three important aspects: (1) an open water and pack ice community is present with some top predator species exhibiting higher abundance associated with moderate sea ice concentration (40–60 %) as opposed to the pack ice edge (10 %), (2) Antarctic fur seals (Arctocephalus gazella) were the most abundant pinniped and they were observed resting on ice floes and foraging within leads and polynyas, and (3) for the most abundant species, spatial regression models indicate that latitude and sea ice concentration (a principal north/south gradient) are the most important environmental determinants. Winter ocean conditions may strongly influence population dynamics of top predators; therefore, information regarding their habitat use during winter is needed for understanding ecosystem dynamics.     

Summer social structure of crabeater seal <Emphasis Type="Italic">Lobodon carcinophaga</Emphasis> in the Amundsen Sea,Antarctica

During the PS75 expedition of ice-breaking RV Polarstern in the Amundsen Sea, in February–March 2010, we studied the at-sea quantitative distribution of the “upper trophic levels,” seabirds and marine mammals. In the Amundsen Sea Embayment, 14,200 pinnipeds belonging to four species were recorded (2100 during 670 half-hour transect counts from the bridge and 12,100 during 50 h of helicopter flight). Crabeater seal Lobodon carcinophaga represented more than 97 % of the total. Two types of major aggregations of crabeaters were noted: on the one hand, very large groups hauled out on the pack ice, composed mainly of adults/bachelors and very few calves. On the other hand, swimming pods of calves were accompanied by one or two leading adults around icebergs. Our interpretation is that, after the beginning of the reproduction period with trios (cow, calf and future father) scattered on pack ice, such pods can be considered the last step of the breeding cycle.     

Combined Use of GPS and Accelerometry Reveals Fine Scale Three-Dimensional Foraging Behaviour in the Short-Tailed Shearwater

Determining the foraging behaviour of free-ranging marine animals is fundamental for assessing their habitat use and how they may respond to changes in the environment. However, despite recent advances in bio-logging technology, collecting information on both at-sea movement patterns and activity budgets still remains difficult in small pelagic seabird species due to the constraints of instrument size. The short-tailed shearwater, the most abundant seabird species in Australia (ca 23 million individuals), is a highly pelagic procellariiform. Despite its ecological importance to the region, almost nothing is known about its at-sea behaviour, in particular, its foraging activity. Using a combination of GPS and tri-axial accelerometer data-loggers, the fine scale three-dimensional foraging behaviour of 10 breeding individuals from two colonies was investigated. Five at-sea behaviours were identified: (1) resting on water, (2) flapping flight, (3) gliding flight, (4) foraging (i.e., surface foraging and diving events), and (5) taking-off. There were substantial intra- and inter- individual variations in activity patterns, with individuals spending on average 45.8% (range: 17.1–70.0%) of time at sea resting on water and 18.2% (range: 2.3–49.6%) foraging. Individuals made 76.4 ± 65.3 dives (range: 8–237) per foraging trip (mean duration 9.0 ± 1.9 s), with dives also recorded during night-time. With the continued miniaturisation of recording devices, the use of combined data-loggers could provide us with further insights into the foraging behaviour of small procellariiforms, helping to better understand interactions with their prey.     

Marine Ecology of Seabirds in Polar Oceans

Patterns of seabird species' distributions differ between theAntarctic and the Arctic. In the Antarctic, distributions areannular or latitudinal, with strong similarities in speciescomposition of seabird communities in all ocean basins at agiven latitude. In the Arctic, communities are arranged meridionally,and show strong differences between ocean basins and, at a givenlatitude, between sides of ocean basins. These differences betweenthe seabird communi ies in the Northern Hemisphere and the SouthernHemisphere reflect differences in the patterns of flow of majorocean current systems. At smaller spatial scales, in both hemispheresthe species composition of seabird communities is sensitiveto changes in watermass characteristics. The distribution of avian biomass is affected by both physicaland biological features of the ocean. In the Antarctic, muchseabird foraging is over deep water, and withinseason, small-scalepatchiness in prey abundance and availability in ice-free watersis likely to be controlledprimarily by the behavior of the prey,rather than by physical features. Thus, prey availability maybe unpredictable in time and space. In contrast, in the NorthernHemisphere, most seabirdforaging is concentrated over shallowcontinental shelves, where currents interact with bathymetryto produce predictable physical features capable of concentratingprey or making prey more easily harvested by seabirds. Ice cover appears to be the most important physical featurein the Antarctic. An entire community of birds is specializedto use prey taken near the ice edge. These prey consist of avariety of species, some of which are normally found much deeperin the water than the birds takingthem can dive. The open-waterportion of the marginal ice zone is also an important foraginghabitat for Antarctic marine birds. In the Arctic, a food webbased on underice algae is used by marine birds, but few ifany data exist on avian use of the open water segment of themarginal ice zone. Recent simultaneous surveys of birds and their prey indicatethat only rarely does the small-scale abundance of birds matchthat of their prey; correlations between predators and preyaregenerally stronger at larger scales. Evidence is accumulatingin the Antarctic that the largestaggregations of krill may bedisproportionately important to foraging seabirds.     

Summer at-sea distribution of little auks Alle alle and harp seals Pagophilus (Phoca) groenlandica in the Fram Strait and the Greenland Sea: impact of small-scale hydrological events

Among the most numerous seabird and pinniped species of the Fram Strait and the Greenland Sea, little auks Alle alle and harp seals Pagophila (Phoca) groenlandica are very abundant in the mixed Polar/Arctic Waters at the front between the two water masses. This must reflect the presence of very high concentrations of their food, Arctic zooplankton and nekton, massively attracting their predators. Such a high biological production seems to be depending on new primary production based on upwelling and high nutrient concentration. This usually takes place at the ice edge (e.g. July 2005), but hydrological conditions such as eddies can modify its position, east of the front in open water as caused by a subsurface eddy (August 2005), or in ice-covered areas if westerly winds push the pack ice to the east, eventually covering an eddy and causing very high concentrations of little auks and harp seals (July 2008). On the other hand, a dramatic decrease of pack ice coverage can move this water mass farther north and west, making it inaccessible to little auks during their breeding season, and apparently causing breeding failure in Jan Mayen in July 2005. In future years, if a much stronger diminution in sea ice coverage will take place, similar to the retreat in 2005 and 2007, the failure might affect the whole Spitsbergen population, as well as other seabird species feeding mainly at the ice edge.     

Distinct patterns of Arctic cod (<Emphasis Type="Italic">Boreogadus saida</Emphasis>) presence and absence in a shallow high Arctic embayment,revealed across open-water and ice-covered periods through acoustic telemetry

With climate change resulting in unpredictable sea ice conditions between years, it is crucial to gain a more comprehensive understanding of the subsequent effects on Arctic marine ecosystems. Arctic cod (Boreogadus saida) play a key role in the Arctic marine food web, serving as a food source that is estimated to contribute up to 75 % of energy transfer to higher trophic levels. To investigate Arctic cod residency and distribution in Resolute Bay (74°44′N, 095°04′W), 85 individuals from four locations in the bay were captured, measured, weighed, implanted with acoustic tags and subsequently tracked on an acoustic array of 49 receivers. Two main periods of residence in the bay were identified, the first in open water and the second under ice cover, and both concluded with a collective mass departure of fish. A generalised linear mixed model was used to investigate the influence of variables on Arctic cod presence/absence in the bay, indicating that ingress and egress were influenced by environmental changes, particularly those associated with the transition from open-water to the ice-covered period. Timing and distribution, during the study period, appeared to be influenced by a combination of physiological acclimation, and a balance between resource availability and refuge from predators. Receiver site Residence Index (RI) analysis revealed strong site fidelity of fish towards the northern areas of the bay, and this behaviour was consistent between tagging groups and individuals, indicating that the majority of tagged cod were representative of a single school. This study represents the first employment of acoustic telemetry to monitor the movements of individual Arctic cod over 9 months, incorporating both open-water and ice-covered periods.     

A gravel-covered iceberg provides an offshore breeding site for ivory gulls <Emphasis Type="Italic">Pagophila eburnea</Emphasis> off Northeast Greenland

The ivory gull Pagophila eburnea is an Arctic seabird species whose distribution is tightly coupled to the availability of sea ice. During the last decades, strong declines have been reported for breeding colonies in Canada and Greenland, which are usually located on nunataks or remote coastal islands. Here, we report the observation of a colony of ivory gulls breeding on a gravel-covered iceberg 70 km off Northeast Greenland in August 2014. It concerned approximately 60 adults, including two ringed individuals, and many chicks. This represents an unusual breeding site for the species, to be compared with a few cases of colonies on gravel-covered sea ice. Breeding on an offshore iceberg may be advantageous since it provides ultimate protection from predators. Furthermore, the proximity to the productive North East Water polynya may have been attractive to these gulls. As a consequence of this and previous observations, colony surveys should not solely focus on inland and coastal breeding habitats, but should be extended towards the ocean.     

北极浮冰生态学研究进展

近年来随着北极地区的开放和全球变化对北极地区生态环境和海冰现存量的影响日益显现,北极浮冰生态学研究得到了广泛的重视和实质性的进展.最新研究结果显示,浮冰本身包含了一个复杂的生物群落,高纬度浮冰生物群落的初级产量远高于原先的估算,浮冰生物群落在北极海洋生态系统中的作用被进一步确认.但由于对浮冰生物群落的研究受后勤保障条件的制约,目前尚有大量科学问题有待今后进一步深入研究,预期我国科学家将在其中做出贡献.     

Climate change impacts on wildlife in a High Arctic archipelago – Svalbard,Norway

The Arctic is warming more rapidly than other region on the planet, and the northern Barents Sea, including the Svalbard Archipelago, is experiencing the fastest temperature increases within the circumpolar Arctic, along with the highest rate of sea ice loss. These physical changes are affecting a broad array of resident Arctic organisms as well as some migrants that occupy the region seasonally. Herein, evidence of climate change impacts on terrestrial and marine wildlife in Svalbard is reviewed, with a focus on bird and mammal species. In the terrestrial ecosystem, increased winter air temperatures and concomitant increases in the frequency of ‘rain‐on‐snow’ events are one of the most important facets of climate change with respect to impacts on flora and fauna. Winter rain creates ice that blocks access to food for herbivores and synchronizes the population dynamics of the herbivore–predator guild. In the marine ecosystem, increases in sea temperature and reductions in sea ice are influencing the entire food web. These changes are affecting the foraging and breeding ecology of most marine birds and mammals and are associated with an increase in abundance of several temperate fish, seabird and marine mammal species. Our review indicates that even though a few species are benefiting from a warming climate, most Arctic endemic species in Svalbard are experiencing negative consequences induced by the warming environment. Our review emphasizes the tight relationships between the marine and terrestrial ecosystems in this High Arctic archipelago. Detecting changes in trophic relationships within and between these ecosystems requires long‐term (multidecadal) demographic, population‐ and ecosystem‐based monitoring, the results of which are necessary to set appropriate conservation priorities in relation to climate warming.     

The insight into diatom diversity,ecology, and biogeography of an extreme cold ultraoligotrophic Lake Labynkyr at the Pole of Cold in the northern hemisphere

The freshwater ultraoligotrophic Lake Labynkyr is located near the Pole of Cold in the northern hemisphere (Yakutia, Russia). The lake is covered by ice during 240 days a year. We undertook several expeditions to the lake during the ice and open water periods for sampling ice fouling, plankton and periphyton that were then analyzed by means of scanning electron microscopy. As a result, we identified a high biodiversity of diatoms—123 species and intraspecific taxa from 53 genera, among them 3 species were new for Russia and 26 taxa were new for the algal flora of Yakutia. The oligo- and xenosaprobionts and their variations dominate—71 taxa. 18 Species were evaluated as tolerant to cold oligotrophic waters, 12 occurred on the ice bottom, and 62 in the water column under ice (0–25 m). 104 taxa were found during the open water period, 70 taxa were identified in the periphyton. We showed the diatom flora of Lake Labynkyr to be unique compared with other lakes of Yakutia and to share taxa with the diatom flora of Lake Baikal. The diatoms being indicators of the global climate changes and ecological status of lakes, our data can be used as an evidence of such changes as well as to be useful studies of biogeography and history of formation of flora in Arctic and Subarctic waters.

     

Using Seabird Habitat Modeling to Inform Marine Spatial Planning in Central California’s National Marine Sanctuaries

Understanding seabird habitat preferences is critical to future wildlife conservation and threat mitigation in California. The objective of this study was to investigate drivers of seabird habitat selection within the Gulf of the Farallones and Cordell Bank National Marine Sanctuaries to identify areas for targeted conservation planning. We used seabird abundance data collected by the Applied California Current Ecosystem Studies Program (ACCESS) from 2004–2011. We used zero-inflated negative binomial regression to model species abundance and distribution as a function of near surface ocean water properties, distances to geographic features and oceanographic climate indices to identify patterns in foraging habitat selection. We evaluated seasonal, inter-annual and species-specific variability of at-sea distributions for the five most abundant seabirds nesting on the Farallon Islands: western gull (Larus occidentalis), common murre (Uria aalge), Cassin’s auklet (Ptychorampus aleuticus), rhinoceros auklet (Cerorhinca monocerata) and Brandt’s cormorant (Phalacrocorax penicillatus). The waters in the vicinity of Cordell Bank and the continental shelf east of the Farallon Islands emerged as persistent and highly selected foraging areas across all species. Further, we conducted a spatial prioritization exercise to optimize seabird conservation areas with and without considering impacts of current human activities. We explored three conservation scenarios where 10, 30 and 50 percent of highly selected, species-specific foraging areas would be conserved. We compared and contrasted results in relation to existing marine protected areas (MPAs) and the future alternative energy footprint identified by the California Ocean Uses Atlas. Our results show that the majority of highly selected seabird habitat lies outside of state MPAs where threats from shipping, oil spills, and offshore energy development remain. This analysis accentuates the need for innovative marine spatial planning efforts and provides a foundation on which to build more comprehensive zoning and management in California’s National Marine Sanctuaries.     

Seabird diversity hotspot linked to ocean productivity in the Canary Current Large Marine Ecosystem

Upwelling regions are highly productive habitats targeted by wide-ranging marine predators and industrial fisheries. In this study, we track the migratory movements of eight seabird species from across the Atlantic; quantify overlap with the Canary Current Large Marine Ecosystem (CCLME) and determine the habitat characteristics that drive this association. Our results indicate the CCLME is a biodiversity hotspot for migratory seabirds; all tracked species and more than 70% of individuals used this upwelling region. Relative species richness peaked in areas where sea surface temperature averaged between 15 and 20°C, and correlated positively with chlorophyll a, revealing the optimum conditions driving bottom-up trophic effects for seabirds. Marine vertebrates are not confined by international boundaries, making conservation challenging. However, by linking diversity to ocean productivity, our research reveals the significance of the CCLME for seabird populations from across the Atlantic, making it a priority for conservation action.     

Spatial variation and low diversity in the major histocompatibility complex in walrus (Odobenus rosmarus)

Increased global temperature and associated changes to Arctic habitats will likely result in the northward advance of species, including an influx of pathogens novel to the Arctic. How species respond to these immunological challenges will depend in part on the adaptive potential of their immune response system. We compared levels of genetic diversity at a gene associated with adaptive immune response [Class II major histocompatibility complex (MHC), DQB exon 2] between populations of walrus (Odobenus rosmarus), a sea ice-dependent Arctic species. Walrus was represented by only five MHC DQB alleles, with frequency differences observed between Pacific and Atlantic populations. MHC DQB alleles appear to be under balancing selection, and most (80 %; n = 4/5) of the alleles were observed in walruses from both oceans, suggesting broad scale differences in the frequency of exposure and diversity of pathogens may be influencing levels of heterozygosity at DQB in walruses. Limited genetic diversity at MHC, however, suggests that walrus may have a reduced capacity to respond to novel immunological challenges associated with shifts in ecological communities and environmental stressors predicted for changing climates. This is particularly pertinent for walrus, since reductions in summer sea ice may facilitate both northward expansion of marine species and associated pathogens from more temperate regions, and exchange of marine mammals and associated pathogens through the recently opened Northwest Passage between the Atlantic and Pacific Oceans in the Canadian high Arctic.     

The biodiversity of the deep Southern Ocean benthos

Our knowledge of the biodiversity of the Southern Ocean (SO) deep benthos is scarce. In this review, we describe the general biodiversity patterns of meio-, macro- and megafaunal taxa, based on historical and recent expeditions, and against the background of the geological events and phylogenetic relationships that have influenced the biodiversity and evolution of the investigated taxa. The relationship of the fauna to environmental parameters, such as water depth, sediment type, food availability and carbonate solubility, as well as species interrelationships, probably have shaped present-day biodiversity patterns as much as evolution. However, different taxa exhibit different large-scale biodiversity and biogeographic patterns. Moreover, there is rarely any clear relationship of biodiversity pattern with depth, latitude or environmental parameters, such as sediment composition or grain size. Similarities and differences between the SO biodiversity and biodiversity of global oceans are outlined. The high percentage (often more than 90%) of new species in almost all taxa, as well as the high degree of endemism of many groups, may reflect undersampling of the area, and it is likely to decrease as more information is gathered about SO deep-sea biodiversity by future expeditions. Indeed, among certain taxa such as the Foraminifera, close links at the species level are already apparent between deep Weddell Sea faunas and those from similar depths in the North Atlantic and Arctic. With regard to the vertical zonation from the shelf edge into deep water, biodiversity patterns among some taxa in the SO might differ from those in other deep-sea areas, due to the deep Antarctic shelf and the evolution of eurybathy in many species, as well as to deep-water production that can fuel the SO deep sea with freshly produced organic matter derived not only from phytoplankton, but also from ice algae.     

Variable sea‐ice conditions influence trophic dynamics in an Arctic community of marine top predators

Sea‐ice coverage is a key abiotic driver of annual environmental conditions in Arctic marine ecosystems and could be a major factor affecting seabird trophic dynamics. Using stable isotope ratios of carbon (δ¹³C) and nitrogen (δ¹⁵N) in eggs of thick‐billed murres (Uria lomvia), northern fulmars (Fulmarus glacialis), glaucous gulls (Larus hyperboreus), and black‐legged kittiwakes (Rissa tridactyla), we investigated the trophic ecology of prebreeding seabirds nesting at Prince Leopold Island, Nunavut, and its relationship with sea‐ice conditions. The seabird community of Prince Leopold Island had a broader isotopic niche during lower sea‐ice conditions, thus having a more divergent diet, while the opposite was observed during years with more extensive sea‐ice conditions. Species' trophic position was influenced by sea ice; in years of lower sea‐ice concentration, gulls and kittiwakes foraged at higher trophic levels while the opposite was observed for murres and fulmars. For murres and fulmars over a longer time series, there was no evidence of the effect of sea‐ice concentration on species' isotopic niche. Results suggest a high degree of adaptation in populations of high Arctic species that cope with harsh and unpredictable conditions. Such different responses of the community isotopic niche also show that the effect of variable sea‐ice conditions, despite being subtle at the species level, might have larger implications when considering the trophic ecology of the larger seabird community. Species‐specific responses in foraging patterns, in particular trophic position in relation to sea ice, are critical to understanding effects of ecosystem change predicted for a changing climate.     

Spatio-temporal overlap between the at-sea distribution of Southern Giant Petrels and fisheries at the Patagonian Shelf

The interactions between seabirds and fisheries pose significant threats for the seabird species such as incidental capture. In contrast, several species of seabirds meet part of their energetic requirements through the use of fisheries discards. Knowledge about the relationship between at-sea distribution of Procellariiformes and fisheries is a key tool in marine ecosystem management. We analysed the spatio-temporal relationship between the areas used by 16 satellite-tracked breeding adults of the Southern Giant Petrel and fisheries distribution and catch at the Patagonian Shelf. We also determined the time spent by adults in different marine jurisdictions. Results indicated a marked spatio-temporal association between birds and fisheries, mainly trawlers. The Southern Giant Petrels concentrated their foraging effort over Argentinean waters. The use of an abundant and predictable food source provided by the fisheries discards may be one of the factors affecting the dynamics of the Southern Giant Petrel populations in Patagonia, Argentina.     

Weak population genetic differentiation in the most numerous Arctic seabird,the little auk

Quantifying patterns of genetic diversity and differentiation among populations of Arctic birds is fundamental for understanding past and ongoing population processes in the Arctic. However, the genetic differentiation of many important Arctic species remains uninvestigated. Here, phylogeography and population genetics were examined in the worldwide population of a small seabird, the little auk (dovekie, Alle alle)—the most numerous avian species of the Arctic ecosystem. Blood samples or feathers were collected from 328 little auks (325 from the nominate subspecies and 3 from the A. a. polaris) in nine main breeding aggregations in the northern Atlantic and one location from the Pacific Ocean. The mtDNA haplotypes of the two subspecies were not segregated into separate groups. Also, no genetic structure was found within the nominate race based on microsatellite markers. The level of genetic differentiation among populations was low yet significant (mean F _ST = 0.005). Some pairwise F _ST comparisons revealed significant differences, including those involving the most distant Pacific colony as well as among some Atlantic populations. Weak population differentiation following the model of isolation by distance in the little auk is similar to the patterns reported in other high-Arctic bird species, indicating that a lack of distinct genetic structure is a common phenomenon in the Arctic avifauna.