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)

Bridging immunogenetics and immunoproteomics: Model positional scanning library analysis for Major Histocompatibility Complex class II DQ in Tursiops truncatus.

The Major Histocompatibility Complex (MHC) is a critical element in mounting an effective immune response in vertebrates against invading pathogens. Studies of MHC in wildlife populations have typically focused on assessing diversity within the peptide binding regions (PBR) of the MHC class II (MHC II) family, especially the DQ receptor genes. Such metrics of diversity, however, are of limited use to health risk assessment since functional analyses (where changes in the PBR are correlated to recognition/pathologies of known pathogen proteins), are difficult to conduct in wildlife species. Here we describe a means to predict the binding preferences of MHC proteins: We have developed a model positional scanning library analysis (MPSLA) by harnessing the power of mixture based combinatorial libraries to probe the peptide landscapes of distinct MHC II DQ proteins. The algorithm provided by NNAlign was employed to predict the binding affinities of sets of peptides generated for DQ proteins. These binding affinities were then used to retroactively construct a model Positional Scanning Library screen. To test the utility of the approach, a model screen was compared to physical combinatorial screens for human MHC II DP. Model library screens were generated for DQ proteins derived from sequence data from bottlenose dolphins from the Indian River Lagoon (IRL) and the Atlantic coast of Florida, and compared to screens of DQ proteins from Genbank for dolphin and three other cetaceans. To explore the peptide binding landscape for DQ proteins from the IRL, combinations of the amino acids identified as active were compiled into peptide sequence lists that were used to mine databases for representation in known proteins. The frequency of which peptide sequences predicted to bind the MHC protein are found in proteins from pathogens associated with marine mammals was found to be significant (p values <0.0001). Through this analysis, genetic variation in MHC (classes I and II) can now be associated with the binding repertoires of the expressed MHC proteins and subsequently used to identify target pathogens. This approach may be eventually applied to evaluate individual population and species risk for outbreaks of emerging diseases