Satellite Tracking of Eastern Chukchi Sea Beluga Whales into the Arctic Ocean

Beluga whales (Delphinapterus leucas) congregate in nearshore waters of the eastern Chukchi Sea, especially in Kotzebue Sound and Kasegaluk Lagoon, in June and July. Where they travel after they leave this area was unknown before this study. We live-captured five belugas in Kasegaluk Lagoon and attached satellite-linked depth recorders to them. The belugas, caught between 26 June and 1 July 1998, were all males, ranging in length from 398 to 440 cm. A 310 cm gray beluga accompanied the smallest male. Two tags transmitted for only about two weeks, during which time one animal remained in the vicinity of Icy Cape, 80 km north of the capture site, and the other traveled to Point Barrow, about 300 km north. The other three tags operated for 60-104 days, and those belugas traveled more than 2000 km, reaching 80° N and 133° W, almost 1100 km north of the Alaska coast. This journey required them to move through 700 km of more than 90% ice cover. Two of the whales then moved southward into the Beaufort Sea north and east of Point Barrow. Two whales later moved to an area north of the Mackenzie River delta, where they spent 2-3 weeks before once again heading southwest towards Barrow. En juin et juillet, des bélougas (Delphinapterus leucas) se rassemblent dans les eaux littorales de l'est de la mer des Tchouktches, en particulier dans le détroit de Kotzebue et la lagune de Kasegaluk. Avant la présente étude, on ne savait pas où ils allaient après avoir quitté la région. Dans la lagune de Kasegaluk, on a capturé vivants cinq bélougas qu'on a équipés de sondeurs acoustiques en liaison avec un satellite. Les bélougas, capturés entre le 26 juin et le 1er juillet 1998, étaient tous de mâles, et mesuraient de 398 à 440 cm de long. Un bélouga gris de 310 cm accompagnait le plus petit mâle. Deux sondes n'ont retransmis que durant deux semaines, au cours desquelles un individu est resté aux environs du cap Icy, à 80 km au nord du site de capture, tandis que l'autre s'est rendu à la pointe Barrow, à environ 300 km au nord. Les trois autres sondes ont fonctionné de 60 à 104 jours, période durant laquelle les bélougas ont parcouru plus de 2000 km, atteignant un point situé à 80° de lat. N. et 133° de long. O., à environ 1100 km au nord de la côte alaskienne. Ce voyage exigeait d'eux qu'ils franchissent 700 km d'eau couverte de glace à plus de 90 p. cent. Deux des baleines ont ensuite viré vers le sud pour pénétrer dans la mer de Beaufort au nord et à l'est de la pointe Barrow. Deux baleines se sont ensuite rendues dans une zone située au nord du delta du Mackenzie, où elles ont passé de 2 à 3 semaines avant de mettre à nouveau le cap sur le sud-ouest, en direction de Barrow.

Dive Behavior of Eastern Chukchi Beluga Whales (Delphinapterus leucas), 1998–2008

We provide an exploratory description of the dive behavior of 23 beluga whales of the eastern Chukchi Sea stock, tagged with satellite-linked time and depth recorders at Point Lay, Alaska, between 1998 and 2007. Because of differences in how transmitters were parameterized, we analyzed data from tags deployed from 1998 to 2002 (n = 20 tags) and data from tags deployed in 2007 (n = 3 tags) separately. Using cluster analysis, we found three basic dive types in the 1998–2002 dataset. “Shallow” diving behavior was characterized by dives mostly 50 m in depth. “Intermediate” diving behavior was characterized by having one mode near the surface and a second mode near 250 m. “Deep” diving behavior was characterized by having one mode near the surface and a second mode more than 400 m from the surface. The average number of dives per hour ranged from 5.1 (SD = 2.1) to 9.8 (SD = 2.9) across dive types, with the fewest dives per hour in the deep diving category. In general, duration of dives ranged from 1 to 18 minutes; however, dives up to 21 minutes occurred in the deepest diving category. We found little evidence that dive behavior of the belugas in our sample varied by sex or age. In general, belugas dove more deeply in the eastern Beaufort Sea than in the western Beaufort or Chukchi Seas. The depths to which belugas most commonly dive in Barrow Canyon and along the Beaufort shelf break (200–300 m) correspond to the boundary where colder Pacific water overlies warmer Atlantic water, which is probably where Arctic cod (Boreogadus saida) are most dense. Diving depths within the Arctic Basin suggest that belugas are foraging mostly within the warm layer of Atlantic Water (~200–1000 m).Nous dressons une description exploratoire du comportement de plongée de 23 bélugas du cheptel de l’est de la mer des Tchouktches dotés de marqueurs d’enregistreurs satellitaires de profondeur temporelle à Point Lay, en Alaska, entre 1998 et 2007. En raison des différences de paramétrage des transmetteurs, nous avons analysé séparément les données de marqueurs déployés de 1998 à 2002 (n = 20 marqueurs) et les données de marqueurs déployés en 2007 (n = 3 marqueurs). Grâce à une analyse par grappes, nous avons trouvé trois types de plongée fondamentaux dans l’ensemble des données de 1998 à 2002. Le comportement de plongée « en eau peu profonde » était principalement caractérisé par des plongées de 50 m de profondeur. Le comportement de plongée « intermédiaire » était caractérisé par un mode de plongée près de la surface et un autre mode à près de 250 m. Le comportement de plongée « en profondeur » était caractérisé par un mode de plongée près de la surface et un deuxième mode à plus de 400 m de la surface. Le nombre moyen de plongées à l’heure variait de 5,1 (écart-type = 2,1) à 9,8 (écart-type = 2,9) pour ce qui est de tous les types de plongée, la catégorie des plongées en profondeur ayant enregistré le moins grand nombre de plongées. En général, la durée des plongées durait de 1 à 18 minutes, mais cela dit, certaines des plongées en profondeur ont duré jusqu’à 21 minutes. Nous avons trouvé peu d’indices portant à croire que le comportement de plongée des bélugas de notre échantillon variait en fonction du sexe ou de l’âge. De manière générale, les bélugas plongeaient plus en profondeur dans l’est de la mer de Beaufort que dans l’ouest de la mer de Beaufort ou dans la mer des Tchouktches. Les profondeurs auxquelles les bélugas plongent le plus souvent dans le canyon Barrow et le long du rebord continental de Beaufort (de 200 à 300 m) correspondent à la limite où l’eau plus froide du Pacifique se superpose à l’eau plus chaude de l’Atlantique, là où la morue polaire (Boreogadus saida) est plus dense. Dans le bassin arctique, la profondeur des plongées suggère que les bélugas s’alimentent surtout dans la couche tempérée d’eau de l’Atlantique (~200 à 1 000 m)

Distribution and Movements of the Teshekpuk Caribou Herd 1990–2005: Prior to Oil and Gas Development

Four caribou (Rangifer tarandus grantii) herds calve on the North Slope of Alaska, three of which have been exposed to little or no resource development. We present 15 years of baseline data on the distribution and movements of 72 satellite-collared and 10 GPS-collared caribou from the Teshekpuk caribou herd (TCH) that have had little to no exposure to oil and gas activities. Fixed-kernel home range analyses of collared caribou revealed that calving grounds were concentrated (i.e., 50% kernel utilization distribution) along the northeastern, eastern, and southeastern shores of Teshekpuk Lake. During the postcalving period, 51% and 35% of caribou moved through two constricted zones to the east and west of Teshekpuk Lake, respectively, and accessed insect-relief habitat along the Beaufort Sea coast. During late summer and early fall, TCH caribou were concentrated to the southeast and southwest of Teshekpuk Lake. Although 65% of the Teshekpuk caribou wintered in two areas on the central coastal plain around the village of Atqasuk and south of Teshekpuk Lake, other TCH animals wintered in a great variety of places, including the Seward Peninsula, the eastern and southern Brooks Range, and the Arctic National Wildlife Refuge. We detected an apparent emigration rate of 6.9%. One male and five female TCH caribou joined the breeding populations of the Western Arctic and Central Arctic herds. TCH caribou traveled an average distance of 2348 ± 190 km annually. Movement rates were at a maximum in midsummer, lowest in winter, and intermediate during spring and fall migrations. Restrictions on oil and gas leasing and surface occupancy have been in place to protect calving, migratory corridors, and insect-relief habitat for the TCH, but these protections are likely to be removed. These data will provide a good baseline that can be used to compare predevelopment distribution and movement patterns of TCH caribou to distribution and movement patterns during and after petroleum development.Quatre hardes de caribous (Rangifer tarandus grantii) vêlent sur la côte nord de l’Alaska, dont trois de ces hardes ont été exposées à peu ou pas d’aménagement des ressources. Nous présentons des données de base échelonnées sur 15 ans relativement à la répartition et aux déplacements de 72 caribous dotés d’un collier émetteur par satellite et de 10 caribous munis d’un collier émetteur GPS de la harde de caribous de Teshekpuk (HCT), caribous qui ont été peu ou pas du tout frottés aux activités pétrolières et gazières. L’analyse du noyau fixe des domaines vitaux des caribous à collier a révélé que les lieux de vêlage étaient concentrés (c’est-à-dire 50 % de la répartition de l’utilisation du noyau) le long des côtes nord-est, est et sud-est du lac Teshekpuk. Après la période de vêlage, 51 pour cent et 35 pour cent des caribous se déplaçaient au sein de deux zones de constriction à l’est et à l’ouest du lac Teshekpuk, respectivement, et accédaient un habitat où se trouvait moins d’insectes sur la côte de la mer de Beaufort. Vers la fin de l’été et le début de l’automne, les caribous de la HCT étaient concentrés au sud-est et au sud-ouest du lac Teshekpuk. Bien que 65 pour cent des caribous de Teshekpuk passaient l’hiver dans deux régions de la plaine côtière centrale autour du village d’Atqasuk et au sud du lac Teshekpuk, les autres bêtes de la HCT passaient l’hiver dans divers endroits, dont la péninsule de Seward, les versants est et sud des montagnes de Brooks et la Réserve faunique nationale de l’Arctique. Nous avons détecté un taux d’émigration apparent de 6,9 pour cent. Un caribou mâle et cinq caribous femelles de la HCT ont rejoint les populations de reproduction des hardes de l’ouest et du centre de l’Arctique. En moyenne, le caribou de la HCT parcourait une distance de 2348 ± 190 km annuellement. Les taux de déplacement étaient à leur point le plus élevé au milieu de l’été, tandis qu’ils étaient à leur niveau le plus bas l’hiver et à un niveau intermédiaire pendant les migrations du printemps et de l’automne. Il existe des restrictions en matière de location et d’occupation en surface pour le pétrole et le gaz afin de protéger le vêlage, les corridors de migration et les habitats à faible taux d’insectes pour la HCT, mais il est vraisemblable que ces restrictions soient éliminées. Ces données fourniront une bonne base pour comparer la répartition et les déplacements du caribou de la HCT avant la mise en valeur des ressources à la répartition et aux déplacements du caribou de la HCT pendant et après la mise en valeur pétrolière

Use of satellite telemetry data, GIS, and HTML to create an interactive display of caribou movements

The use of animation clearly reveals the large annual variation in wintering areas and large differences in daily movement rates for this herd. This interactive display can be adapted for school groups, subsistence hunters, the general public, or scientists

Use of satellite telemetry to evaluate movements of caribou within subsistence hunting areas in northern Alaska

Caribou from the Teshekpuk Herd (TH) are an important subsistence resource for residents of Inupiaq villages in northern Alaska. In recent years the use of satellite telemetry has increased the understanding of the herd's annual movements and interactions with other herds. Most caribou of the TH are within the National Petroleum Reserve—Alaska (NPRA) throughout the year. The northeastern portion of NPRA has undergone two lease sales for oil and gas exploration, and lease sales are tentatively scheduled for the central/northwest portion of the NPRA in 2004. During 1990—1999, the movements of 27 caribou from the TH were tracked using satellite collars. We evaluated the proportion of time caribou were available to Inupiaq hunters by incorporating maps depicting subsistence-use areas for each of seven Inupiaq villages, and then examining seasonal and annual movements of caribou relative to those areas. By combining caribou locations with subsistence hunting areas, we were able to explore spatial and temporal patterns in caribou availability to subsistence hunters. This information is useful for managers to set appropriate hunting regulations and for devising sensible alternatives and mitigation of likely petroleum development in NPRA

Population Genetics of Bowhead Whales (Baleana mysticetus) in the Western Arctic

Bowhead whales (Balaena mysticetus) in the Bering, Chukchi, and Beaufort seas experienced a severe reduction as a result of commercial whaling in the 19th century. Since the cessation of commercial whaling, the population has recovered to a size that is approaching pre-whaling estimates. Inupiat and Yupik communities in northern and western Alaska hunt these Western Arctic (WA) bowheads along their migratory path during spring and fall. This hunting is regulated by the International Whaling Commission. Recent but preliminary analysis of available genetic data (207 whales and 10 microsatellite markers) raised the question of the presence of multiple, genetically distinct populations within the WA bowheads. Here we re-examined this question on the basis of a study of 414 whales and 22 newly developed microsatellite loci. We identified widespread departures from Hardy-Weinberg equilibrium; however, we were unable to detect significant evidence of multiple genetic populations within the WA bowheads that could explain this Hardy-Weinberg disequilibrium, particularly when compared to the strength of evidence for differentiation between WA bowheads and other populations from distant regions such as the Okhotsk Sea and eastern Canada. There was conclusive evidence of genetic differentiation among the three regions. The statistical rejection of panmixia within the WA improves our understanding of bowhead whale biology, and the lack of evidence for multiple populations within the WA enables risk-averse management of aboriginal hunting of Western Arctic bowhead whales.La population de baleines boréales (Balaena mysticetus) des mers de Béring, de Tchoukotka et de Beaufort a enregistré un grave déclin en raison de la pêche commerciale à la baleine au XIXe siècle. Depuis que la pêche commerciale à la baleine a cessé, la population de baleines boréales a connu un certain essor au point où elle approche maintenant les estimations de la taille qu’elle avait avant la pêche commerciale à la baleine. Les collectivités Inupiat et Yupik du nord et de l’ouest de l’Alaska chassent les baleines boréales de l’ouest de l’Arctique le long de leur voie de migration au printemps et à l’automne. La chasse est réglementée par l’International Whaling Commission. Des analyses récentes, bien que préliminaires, des données génétiques disponibles (207 baleines et 10 marqueurs microsatellites) ont soulevé la question de la présence de multiples populations génétiquement distinctes au sein de la population de baleines boréales de l’ouest de l’Alaska. Ici, nous avons réexaminé cette question en fonction de l’étude de 414 baleines et de 22 locis microsatellites nouvellement mis au point. Nous avons remarqué d’importantes déviations de l’équilibre de Hardy-Weinberg; toutefois, nous n’avons pas pu trouver de preuve significative de populations génétiques multiples au sein des baleines boréales de l’ouest de l’Alaska qui pourrait expliquer ce déséquilibre de Hardy-Weinberg, plus particulièrement en comparaison avec la force de la preuve de différenciation entre les baleines boréales de l’ouest de l’Arctique et d’autres populations de régions distantes telles que la mer d’Okhotsk et l’est du Canada. Il y avait des preuves concluantes de différenciation génétique entre les trois régions. Le rejet statistique de la panmixie au sein de l’ouest de l’Arctique améliore notre compréhension de la biologie des baleines boréales, et le manque de preuves de populations multiples dans l’ouest de l’Arctique donne lieu à la gestion de l’aversion au risque de la chasse à la baleine boréale de l’ouest de l’Arctique par les Autochtones

Beluga whales in the western Beaufort Sea : current state of knowledge on timing, distribution, habitat use and environmental drivers

ECG was supported by a National Research Council-National Academy of Sciences Postdoctoral Fellowship.The seasonal and geographic patterns in the distribution, residency, and density of two populations (Chukchi and Beaufort) of beluga whales (Delphinapterus leucas) were examined using data from aerial surveys, passive acoustic recordings, and satellite telemetry to better understand this arctic species in the oceanographically complex and changing western Beaufort Sea. An aerial survey data-based model of beluga density highlights the Beaufort Sea slope as important habitat for belugas, with westerly regions becoming more important as summer progresses into fall. The Barrow Canyon region always had the highest relative densities of belugas from July-October. Passive acoustic data showed that beluga whales occupied the Beaufort slope and Beaufort Sea from early April until early November and passed each hydrophone location in three broad pulses during this time. These pulses likely represent the migrations of the two beluga populations: the first pulse in spring being from Beaufort animals, the second spring pulse Chukchi belugas, with the third, fall pulse a combination of both populations. Core-use and home range analyses of satellite-tagged belugas showed similar use of habitats as the aerial survey data, but also showed that it is predominantly the Chukchi population of belugas that uses the western Beaufort, with the exception of September when both populations overlap. Finally, an examination of these beluga datasets in the context of wind-driven changes in the local currents and water masses suggests that belugas are highly capable of adapting to oceanographic changes that may drive the distribution of their prey.PostprintPeer reviewe

Functional and Structural Insights Revealed by Molecular Dynamics Simulations of an Essential RNA Editing Ligase in Trypanosoma brucei

RNA editing ligase 1 (TbREL1) is required for the survival of both the insect and bloodstream forms of Trypanosoma brucei, the parasite responsible for the devastating tropical disease African sleeping sickness. The type of RNA editing that TbREL1 is involved in is unique to the trypanosomes, and no close human homolog is known to exist. In addition, the high-resolution crystal structure revealed several unique features of the active site, making this enzyme a promising target for structure-based drug design. In this work, two 20 ns atomistic molecular dynamics (MD) simulations are employed to investigate the dynamics of TbREL1, both with and without the ATP substrate present. The flexibility of the active site, dynamics of conserved residues and crystallized water molecules, and the interactions between TbREL1 and the ATP substrate are investigated and discussed in the context of TbREL1's function. Differences in local and global motion upon ATP binding suggest that two peripheral loops, unique to the trypanosomes, may be involved in interdomain signaling events. Notably, a significant structural rearrangement of the enzyme's active site occurs during the apo simulations, opening an additional cavity adjacent to the ATP binding site that could be exploited in the development of effective inhibitors directed against this protozoan parasite. Finally, ensemble averaged electrostatics calculations over the MD simulations reveal a novel putative RNA binding site, a discovery that has previously eluded scientists. Ultimately, we use the insights gained through the MD simulations to make several predictions and recommendations, which we anticipate will help direct future experimental studies and structure-based drug discovery efforts against this vital enzyme

Biochemical, Structural and Molecular Dynamics Analyses of the Potential Virulence Factor RipA from Yersinia pestis

Human diseases are attributed in part to the ability of pathogens to evade the eukaryotic immune systems. A subset of these pathogens has developed mechanisms to survive in human macrophages. Yersinia pestis, the causative agent of the bubonic plague, is a predominately extracellular pathogen with the ability to survive and replicate intracellularly. A previous study has shown that a novel rip (required for intracellular proliferation) operon (ripA, ripB and ripC) is essential for replication and survival of Y. pestis in postactivated macrophages, by playing a role in lowering macrophage-produced nitric oxide (NO) levels. A bioinformatics analysis indicates that the rip operon is conserved among a distally related subset of macrophage-residing pathogens, including Burkholderia and Salmonella species, and suggests that this previously uncharacterized pathway is also required for intracellular survival of these pathogens. The focus of this study is ripA, which encodes for a protein highly homologous to 4-hydroxybutyrate-CoA transferase; however, biochemical analysis suggests that RipA functions as a butyryl-CoA transferase. The 1.9 Å X-ray crystal structure reveals that RipA belongs to the class of Family I CoA transferases and exhibits a unique tetrameric state. Molecular dynamics simulations are consistent with RipA tetramer formation and suggest a possible gating mechanism for CoA binding mediated by Val227. Together, our structural characterization and molecular dynamic simulations offer insights into acyl-CoA specificity within the active site binding pocket, and support biochemical results that RipA is a butyryl-CoA transferase. We hypothesize that the end product of the rip operon is butyrate, a known anti-inflammatory, which has been shown to lower NO levels in macrophages. Thus, the results of this molecular study of Y. pestis RipA provide a structural platform for rational inhibitor design, which may lead to a greater understanding of the role of RipA in this unique virulence pathway