Polar Bear Distribution and Habitat Association Reflect Long-term Changes in Fall Sea Ice Conditions in the Alaskan Beaufort Sea

The polar bear (Ursus maritimus) is considered an indicator species of ecosystem health because of its longevity, life-history requirements, reliance on sea ice (i.e., sea ice obligate), and position in the Arctic food web. Polar bear distribution and habitat association should both be reliable signals for environmental perturbation, as the bears respond behaviorally to changes in sea ice extent, the timing and duration of ice formation, and ablation. Polar bears and sea ice conditions were monitored as part of the annual fall bowhead whale (Balaena mysticetus) aerial survey in the Alaskan Beaufort Sea between 1979 and 2005. Habitats associated with polar bear sightings changed during the study, with fewer bears associated with ice (irrespective of ice type and percent) and more bears associated with land and open water. Large-scale differences were documented for both ice type and percent ice cover, particularly in September. In general, the pattern in September (and to a lesser extent in October) included a reduction in old ice and a concomitant increase in open water. In addition, there was an eastward and landward shift in polar bear sightings. From 1979 to 1987, polar bears were observed primarily on ice along the shelf break near Barrow, whereas from 1997 to 2005, polar bears were observed on barrier islands or along the mainland coast near Kaktovik. The changes in polar bear distribution and habitat association appear to reflect a behavioral response by polar bears to changes in ice (type and percent cover) and in the timing of ice formation and ablation.L’ours polaire (Ursus maritimus) est considéré comme une espèce indicatrice de la santé de l’écosystème en raison de sa longévité, des besoins de son cycle biologique, de sa dépendance de la glace de mer (c’est-à-dire la glace de mer obligatoire) et de la position qu’il occupe dans le réseau alimentaire de l’Arctique. La répartition de l’ours polaire et son association à un habitat devraient tous deux constituer des signaux fiables en matière de perturbation de l’environnement car le comportement des ours varie en fonction des changements caractérisant l’étendue de glace de mer, la synchronisation et la durée de la formation de la glace, de même que l’ablation. Les ours polaires et les conditions de la glace de mer ont fait l’objet d’une surveillance dans le cadre du levé aérien annuel de la baleine boréale (Balaena mysticetus) effectué à l’automne dans la mer de Beaufort alaskienne entre 1979 et 2005. Au cours de l’étude, les habitats liés aux observations d’ours polaires ont évolué, un moins grand nombre d’ours étant associés à la glace (sans égard au type et au pourcentage de glace) et un plus grand nombre d’ours étant associés à la terre et à l’eau libre. Les différences à grande échelle ont été répertoriées tant pour le type de glace que pour le pourcentage de couche de glace, particulièrement en septembre. En général, la tendance en septembre (et en octobre, dans une moindre mesure) comprenait une réduction de l’ancienne glace de même qu’une augmentation concomitante dans l’eau libre. De plus, on a enregistré un décalage vers l’est et vers l’intérieur des terres en ce qui a trait aux observations d’ours polaires. De 1979 à 1987, les ours polaires ont surtout été observés sur la glace le long du rebord continental près de Barrow, tandis que de 1997 à 2005, les ours polaires ont été observés sur les îles-barrières ou le long de la côte continentale près de Kaktovik. Les changements caractérisant la répartition des ours polaires et l’association à un habitat semblent refléter une réaction comportementale des ours polaires vis-à-vis des changements relatifs à la glace (le type et le pourcentage de la couche) ainsi que de la synchronisation de la formation et de l’ablation de la glace

Beavers, Castor canadensis, Feeding on Salmon Carcasses: Opportunistic Use of a Seasonally Superabundant Food Source

We report observations of Beavers (Castor canadensis) foraging and feeding on discarded Chinook Salmon (Oncorhynchus tshawytscha) carcasses within the confines of the Susitna River drainage in southcentral Alaska on three separate occasions between 1999 and 2004. In all three instances, Beavers were observed actively seeking out freshly discarded carcasses or transporting “fresh” salmon carcasses in their mouths. In one instance, Beavers were seen using their dextrous forefeet to “handle” chunks of salmon while hunched over carcasses and in this case we actually witnessed Beavers “chewing” and ingestion was assumed. In the other two instances, Beavers were observed swimming with salmon carcasses in their mouths. Though unique within the framework of Beaver foraging ecology, we suggest this behavior may be a fairly common strategy employed by Beavers in Alaskan streams and rivers to take advantage of a seasonally superabundant source of protein

Offshore Distances of Bowhead Whales (Balaena mysticetus) Observed during Fall in the Beaufort Sea, 1982–2000: An Alternative Interpretation

Nineteen years (1982– 2000) of sighting data from fall aerial surveys of bowhead whales (Balaena mysticetus) in the Alaskan Beaufort Sea were analyzed to determine how patterns in the distribution of migrating bowhead whales relate to annual sea-ice conditions. Transect sighting rate (transect sightings/km) indicated (ANOVA; F2, 980 = 143.84, p < 0.0001) that bowhead whales occurred farther offshore in years of heavy ice conditions (73.4 km, 95% CL: 67.2–79.6 km) than in years of moderate (49.3 km, 95% CL: 44.8–53.84 km), or light (31.2 km, 95% CL: 30.0–32.4 km) ice conditions. The most plausible explanation for the observed pattern in bowhead whale distribution is that in years of heavy ice conditions (annual pack ice; 1983, 1988, 1991), the developing landfast ice limits availability of shallow nearshore habitat, thus necessitating use of leads and ice openings in deeper water. We acknowledge that factors such as bathymetry, ocean currents, transport, and food availability may also interact to influence autumn distribution of bowhead whales. In heavy ice years, however, these factors likely exert less influence on bowhead whale distribution than in years with light to moderate ice conditions.Les données automnales prélevées à partir de relevés aériens pendant 19 années chez les baleines boréales (1982– 2000) (Balaena mysticetus) de la mer de Beaufort alaskienne ont été analysées dans le but de déterminer comment les tendances caractérisant la répartition des baleines boréales en migration se rapportent à l’état annuel des glaces et de la mer. Le taux de repérage transect (repérage transect/km) a indiqué (ANOVA; F2, 980 = 143.84, p < 0,0001) que les baleines boréales se trouvaient plus loin au large pendant les années où il y avait beaucoup de glace (73,4 km, 95 % CL: 67,2–79,6 km) que pendant les années où la glace était modérée (49,3 km, 95 % CL: 44,8–53.84 km) ou légère (31,2 km, 95 % CL: 30,0–32,4 km). L’explication la plus plausible à la source de la tendance qui a été observée en matière de répartition des baleines boréales, c’est que pendant les années où il y a beaucoup de glace (banquise; 1983, 1988, 1991), la glace de rive en formation limite la disponibilité d’habitats de faible profondeur à proximité du littoral, ce qui nécessite l’utilisation de chenaux et d’ouvertures dans la glace en eau plus profonde. On reconnaît que des facteurs comme la bathymétrie, les courants océaniques, le transport et la disponibilité de la nourriture peuvent également entrer en interaction au point d’exercer une influence sur la répartition automnale des baleines boréales. Cependant, pendant les années où il y a beaucoup de glace, ces facteurs sont susceptibles d’exercer moins d’influence sur la répartition des baleines boréales que pendant les années où la couverture de glace varie de légère à moyenne

Late Summer Movements by Giant Canada Geese in Relation to a September Hunting Season

The population of giant Canada geese (Branta canadensis maxima) breeding in eastern South Dakota has increased dramatically since reintroduction efforts began in the 1960s. May breeding population levels of giant Canada geese exceeded population management goals set by the South Dakota Department of Game, Fish and Parks (SDGFP) by the mid-1990s, and the population has continued to increase into the 2000s. This population increase was accompanied by an increase in goose-related conflicts such as crop depredation. In 1996, a September hunting season was implemented in select counties in eastern South Dakota in an effort to reduce the giant Canada goose population. After its implementation, some hunters and biologists were concerned that the early September season was causing Canada geese to disperse from areas open to hunting due to hunting pressure. Herein, we describe post-molt movements by geese, particularly in relation to the September hunting season. We caught Canada geese in 7 counties in eastern South Dakota during the summer molting period, 2000 to 2003. We attached VHF (n = 153) and satellite transmitters (n = 43) on adult female geese with broods. We monitored movements of marked geese weekly from July through the fall freezing period. For this study, we considered major movements any postmolt movement ≥40 km from the wetland in which the goose was banded prior to October 15. Forty-six percent of marked geese made major movements from July to September, and 43% moved during the first week of the September season, indicating that the season may have triggered their post-molt movement. Major movements were primarily in a northerly direction, and the longest documented post-molt movement was 474 km north. It appears that the onset of the September hunting season may have caused geese to move immediately before or during the first 10 days of the season. Post-molt movements prior to the September hunting season may simply have been a function of established, learned traditions, but the punctuated movement of geese during the opening weekend of the hunting season may have resulted from geese responding to the hunting season itself

Harvest Demographics of Temperate-breeding Canada Geese in South Dakota, 1967–1995

In South Dakota, breeding giant Canada geese (Branta canadensis maxima) have increased substantially, and harvest management strategies have been implemented to maximize hunting opportunity (e.g., special early-September seasons) on local, as well as molt-migrant giant Canada geese (B. c. interior) while still protecting lesser abundant Arcticbreeding Canada geese and cackling geese (e.g., B. hutchinsii, B. minima). Information on important parameters, such as survival and recovery rates, are generally lacking for giant Canada geese in the northern Great Plains. Patterns in Canada goose band recoveries can provide insight into the distribution, chronology, and harvest pressures to which a given goose population segment is exposed. We studied spatial and temporal recovery patterns of molting Canada geese during annual banding efforts in South Dakota between 1967 and 1995. Recovery rates (% ± SE) for Canada geese increased over time in both western South Dakota (0.034 ± 0.005 [1967 to 1976], 0.056 ± 0.009 [1977 to 1986]) and eastern (0.026 ± 0.002 [1967 to 1978], 0.058 ± 0.003 [1987 to 1995]) South Dakota. Although recovery rates for Canada geese west of the Missouri River (WR) and east of the Missouri River (ER) were relatively similar, recovery distribution and harvest chronology indicate spatial and temporal differences for geese banded in these 2 geographic regions. Overall, Canada geese banded in South Dakota were recovered in 23 states and 5 Canadian provinces, and recovery distribution varied relative to banding region. Distribution of recoveries suggests a south-southwesterly movement for WR-banded geese compared to a south-southeasterly movement for ERbanded geese. For WR-banded geese, 40 to 52% and 30 to 34% of direct and indirect recoveries, respectively, occurred in December. In contrast, for ER-banded geese, 19 to 38% and 15 to 19% of direct and indirect recoveries, respectively, occurred in December. Waterfowl managers need to consider that recovery rates and harvest chronology of banded giant Canada geese may vary geographically within a state or province. Refinement of harvest management strategies at multiple spatial scales may be required

Natural Killer Cell Killing of Acute Myelogenous Leukemia and Acute Lymphoblastic Leukemia Blasts by Killer Cell Immunoglobulin-Like Receptor–Negative Natural Killer Cells after NKG2A and LIR-1 Blockade

Although the study of natural killer (NK) cell alloreactivity has been dominated by studies of killer cell immunoglobulin-like receptors (KIRs), we hypothesized that NKG2A and LIR-1, present on 53% ± 13% and 36% ± 18% of normal NK cells, respectively, play roles in the NK cell killing of primary leukemia targets. KIR- cells, which compose nearly half of the circulating NK cell population, exhibit tolerance to primary leukemia targets, suggesting signaling through other inhibitory receptors. Both acute myelogenous leukemia and acute lymphoblastic leukemia targets were rendered susceptible to lysis by fresh resting KIR- NK cells when inhibitory receptor–major histocompatibility class I interactions were blocked by pan-HLA antibodies, demonstrating that these cells are functionally competent. Blockade of a single inhibitory receptor resulted in slightly increased killing, whereas combined LIR-1 and NKG2A blockade consistently resulted in increased NK cell cytotoxicity. Dual blockade of NKG2A and LIR-1 led to significant killing of targets by resting KIR- NK cells, demonstrating that this population is not hyporesponsive. Together these results suggest that alloreactivity of a significant fraction of KIR- NK cells is mediated by NKG2A and LIR-1. Thus strategies to interrupt NKG2A and LIR-1 in combination with anti-KIR blockade hold promise for exploiting NK cell therapy in acute leukemias

The International Surface Pressure Databank version 2

The International Surface Pressure Databank (ISPD) is the world's largest collection of global surface and sea-level pressure observations. It was developed by extracting observations from established international archives, through international cooperation with data recovery facilitated by the Atmospheric Circulation Reconstructions over the Earth (ACRE) initiative, and directly by contributing universities, organizations, and countries. The dataset period is currently 1768–2012 and consists of three data components: observations from land stations, marine observing systems, and tropical cyclone best track pressure reports. Version 2 of the ISPD (ISPDv2) was created to be observational input for the Twentieth Century Reanalysis Project (20CR) and contains the quality control and assimilation feedback metadata from the 20CR. Since then, it has been used for various general climate and weather studies, and an updated version 3 (ISPDv3) has been used in the ERA-20C reanalysis in connection with the European Reanalysis of Global Climate Observations project (ERA-CLIM). The focus of this paper is on the ISPDv2 and the inclusion of the 20CR feedback metadata. The Research Data Archive at the National Center for Atmospheric Research provides data collection and access for the ISPDv2, and will provide access to future versions

The Caenorhabditis elegans GATA Factor ELT-1 Works through the Cell Proliferation Regulator BRO-1 and the Fusogen EFF-1 to Maintain the Seam Stem-Like Fate

Seam cells in Caenorhabditis elegans provide a paradigm for the stem cell mode of division, with the ability to both self-renew and produce daughters that differentiate. The transcription factor RNT-1 and its DNA binding partner BRO-1 (homologues of the mammalian cancer-associated stem cell regulators RUNX and CBFβ, respectively) are known rate-limiting regulators of seam cell proliferation. Here, we show, using a combination of comparative genomics and DNA binding assays, that bro-1 expression is directly regulated by the GATA factor ELT-1. elt-1(RNAi) animals display similar seam cell lineage defects to bro-1 mutants, but have an additional phenotype in which seam cells lose their stem cell-like properties and differentiate inappropriately by fusing with the hyp7 epidermal syncytium. This phenotype is dependent on the fusogen EFF-1, which we show is repressed by ELT-1 in seam cells. Overall, our data suggest that ELT-1 has dual roles in the stem-like seam cells, acting both to promote proliferation and prevent differentiation