Contemporary Diet of Bowhead Whales (Balaena mysticetus) from the Eastern Canadian Arctic Inferred from Fatty Acid Biomarkers

The diet and feeding ecology of Eastern Canada – West Greenland bowhead whales were examined using fatty acid (FA) composition of the outer blubber layer of 50 individuals sampled during the summers of 2008 and 2009. Bowhead blubber was rich in the following FAs: 14:0, 16:0, 16:1n – 7, 18:0, 18:1n – 11, 18:1n – 9, 18:1n – 7, 20:1n – 11, 20:1n – 9, 20:1n – 7, 20:5n – 3, 22:1n – 11, 22:1n – 9, 22:5n – 3, and 22:6n – 3, which together accounted for 91% of total FAs identified. Four groups of bowhead whales were identified from their FA signatures using multivariate analysis. Long-chain monounsaturated fatty acids (MUFAs) (20:1n – 9, 20:1n – 11, 22:1n – 9 and 22:1n – 11) and polyunsaturated fatty acids (PUFAs) (20:5n – 3, 22:5n – 3, 22:6n – 3) accounted for most of the variance among groups. Whales from a single sampling site segregated into different groups, some of which included whales from other sampling sites, suggesting summer mixing of whales from different wintering areas and prey assemblages, or alternatively, selective feeding. FA composition was similar in males and females and among whales of different age classes, which suggests that these different groups shared foraging areas and had similar diets. The blubber of bowhead whales from the eastern Canadian Arctic was composed of high proportions of calanoid copepod markers (20:1n – 9 and 22:1n – 11), especially compared to the adipose tissue of western Arctic bowhead whales. This finding suggests that Calanus spp. were likely a major prey item. Given the expected change in Arctic zooplankton assemblages with climate warming, bowhead whales, through their FA biomarkers, may serve as sentinels of change in Arctic ecosystems.Afin d’approfondir les connaissances sur la diète et l’écologie alimentaire de la baleine boréale de la population EC-WG, nous avons examiné la composition en acides gras de la couche de graisse sous-cutanée de 50 animaux échantil­lonnés durant les étés 2008 et 2009. Les baleines boréales étaient riches en certains acides gras (AG) notamment 14:0, 16:0, 16:1n-7, 18:0, 18:1n-11, 18:1n-9, 18:1n-7, 20:1n-11, 20:1n-9, 20:1n-7, 20:5n-3, 22:1n-11, 22:1n-9, 22:5n-3 et 22:6n-3. Ces 15 acides gras constituaient 91 % de tous les acides gras identifiés. Nous avons identifié quatre groupes de baleines à l’aide d’une analyse composée principale dans une analyse de fonction discriminante. Les acides gras monoinsaturés à longue chaîne (MUFAs) (20:1n-9, 20:1n-11, 22:1n-9 et 22:1n-11) et les acides gras Oméga-3 polyinsaturés (PUFAs) (20:5n-3, 22:5n-3 et 22:6n3) étaient responsables de la majorité de la variance entre les groupes de baleines. Chacun des quatre groupes de baleines était constitué d’animaux provenant d’une même région ainsi que de régions différentes. Ces résultats suggèrent que des baleines boréales avec des sites d’hivernage différents partagent un même site d’alimentation estival et/ou que les baleines boréales ont une alimentation sélective. La composition en acide gras du tissu adipeux était semblable chez les mâles et les femelles ainsi qu’entre les individus de différentes classes de tailles, ce qui suggère une diète similaire ou des aires d’alimentation communes. Le tissu adipeux des baleines boréales de l’Arctique de l’Est canadien était constitué d’une plus grande proportion de marqueurs spécifiques de copépodes calanoides (20:1n – 9 et 22:1n – 11) comparativement aux baleines boréales de l’Arctique de l’Ouest. Les résultats de notre étude suggèrent que Calanus spp. est une proie importante de la diète des baleines boréales de la population de l’est du Canada et de l’ouest du Groenland. Compte tenu de l’évolution attendue dans les assemblages de zooplancton de l’Arctique en raison du réchauffement climatique, les baleines boréales, par leurs biomarqueurs AG, peuvent servir de sentinelles des changements dans les écosystèmes.

Revisiting the link between depression symptoms and high school dropout : timing of exposure matters

Purpose Recent reviews concluded that past depression symptoms are not independently associated with high school dropout, a conclusion that could induce schools with high dropout rates and limited resources to consider depression screening, prevention, and treatment as low-priority. Even if past symptoms are not associated with dropout, however, it is possible that recent symptoms are. The goal of this study was to examine this hypothesis. Methods In 12 disadvantaged high schools in Montreal (Canada), all students at least 14 years of age were first screened between 2012 and 2015 (Nscreened = 6,773). Students who dropped out of school afterward (according to school records) were then invited for interviews about their mental health in the past year. Also interviewed were matched controls with similar risk profiles but who remained in school, along with average not at-risk schoolmates (Ninterviewed = 545). Interviews were conducted by trained graduate students. Results Almost one dropout out of four had clinically significant depressive symptoms in the 3 months before leaving school. Adolescents with recent symptoms had an odd of dropping out more than twice as high as their peers without such symptoms (adjusted odds ratio = 2.17; 95% confidence interval = 1.14–4.12). In line with previous findings, adolescents who had recovered from earlier symptoms were not particularly at risk. Conclusions These findings suggest that to improve disadvantaged youths' educational outcomes, investments in comprehensive mental health services are needed in schools struggling with high dropout rates, the very places where adolescents with unmet mental health needs tend to concentrate

Individual and population dietary specialization decline in fin whales during a period of ecosystem shift

Abstract This study sought to estimate the effect of an anthropogenic and climate-driven change in prey availability on the degree of individual and population specialization of a large marine predator, the fin whale (Balaenoptera physalus). We examined skin biopsies from 99 fin whales sampled in the St. Lawrence Estuary (Canada) over a nine year period (1998–2006) during which environmental change was documented. We analyzed stable isotope ratios in skin and fatty acid signatures in blubber samples of whales, as well as in seven potential prey species, and diet was quantitatively assessed using Bayesian isotopic models. An abrupt change in fin whale dietary niche coincided with a decrease in biomass of their predominant prey, Arctic krill (Thysanoessa spp.). This dietary niche widening toward generalist diets occurred in nearly 60% of sampled individuals. The fin whale population, typically composed of specialists of either krill or lipid-rich pelagic fishes, shifted toward one composed either of krill specialists or true generalists feeding on various zooplankton and fish prey. This change likely reduced intraspecific competition. In the context of the current “Atlantification” of northern water masses, our findings emphasize the importance of considering individual-specific foraging tactics and not only population or group average responses when assessing population resilience or when implementing conservation measures

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Baleen whale microsatellite panel for individual identification and parentage assignment in Mysticeti

Highly polymorphic single tandem repeat loci (STR, also known as microsatellite loci) remain a familiar, cost efficient class of genetic markers in genetic studies in ecology, behavior and conservation. Here we characterize a new, universal set of ten STR loci in seven species of baleen whales, optimized for PCR amplification in two multiplex reactions along with a Y chromosome marker for sex determination. The optimized, universal set of STR loci provides a convenient starting point for new genetic studies in baleen whales aimed at identifying individuals and populations. Data from the new STR loci were combined with genotypes from previously published STR loci to assess the power to assign parentage using paternity exclusion in four species: fin whale (Balaenoptera physalus), humpback whale (Megaptera novaeangliae), blue whale (B. musculus) and bowhead whale (Balaena mysticetus). Our results suggest that parentage studies should always be accompanied by a power analysis in order to ascertain that each individual specific study is based upon data with sufficient power to assign parentage with statistical rigor

From Sea to Sea: Canada's Three Oceans of Biodiversity

Evaluating and understanding biodiversity in marine ecosystems are both necessary and challenging for conservation. This paper compiles and summarizes current knowledge of the diversity of marine taxa in Canada's three oceans while recognizing that this compilation is incomplete and will change in the future. That Canada has the longest coastline in the world and incorporates distinctly different biogeographic provinces and ecoregions (e.g., temperate through ice-covered areas) constrains this analysis. The taxonomic groups presented here include microbes, phytoplankton, macroalgae, zooplankton, benthic infauna, fishes, and marine mammals. The minimum number of species or taxa compiled here is 15,988 for the three Canadian oceans. However, this number clearly underestimates in several ways the total number of taxa present. First, there are significant gaps in the published literature. Second, the diversity of many habitats has not been compiled for all taxonomic groups (e.g., intertidal rocky shores, deep sea), and data compilations are based on short-term, directed research programs or longer-term monitoring activities with limited spatial resolution. Third, the biodiversity of large organisms is well known, but this is not true of smaller organisms. Finally, the greatest constraint on this summary is the willingness and capacity of those who collected the data to make it available to those interested in biodiversity meta-analyses. Confirmation of identities and intercomparison of studies are also constrained by the disturbing rate of decline in the number of taxonomists and systematists specializing on marine taxa in Canada. This decline is mostly the result of retirements of current specialists and to a lack of training and employment opportunities for new ones. Considering the difficulties encountered in compiling an overview of biogeographic data and the diversity of species or taxa in Canada's three oceans, this synthesis is intended to serve as a biodiversity baseline for a new program on marine biodiversity, the Canadian Healthy Ocean Network. A major effort needs to be undertaken to establish a complete baseline of Canadian marine biodiversity of all taxonomic groups, especially if we are to understand and conserve this part of Canada's natural heritage

Contribution à la validation fonctionnelle du gène majeur contrôlant la dureté / tendreté de l'albumen du grain de blé par l'étude de lignées quasi-isogéniques

Wheat grain hardness, a major trait for endosperm texture and flour end-use properties, is strongly associated to absence or modification of puroindolines. To gain insight into biological function of those proteins in bread wheat kernel (Triticum aestivum L.), puroindolines’ subcellular localization was sought by immunocytochemistry and proteomes were analyzed at four stages of developing kernels in two near-isogenic lines for hardness, differing mainly in the absence of Pina in the Hardline. As early as the end of endosperm cellularisation, puroindolines were localized onto vesicular membranes and into protein bodies, where storage proteins accumulate. Using AFFFF (Asymmetrical Flow Field-Flow Fractionation), we observed a correlation between hardness and storage protein polymer size. Proteomic analyses of the albumin/globulin and amphiphilic fractions revealed an increase in folding and stress-related proteins in the Hard line, as compared to the Soft one. Both ultrastructural and proteomic studies suggested also that the Hard/Soft genotype affects the kinetics of kernel development. These lines of evidence imply that puroindolines interact with storage proteins and display the same routage. Puroindolines could therefore be involved in prolamines folding and assembly mechanisms.La dureté du grain de blé est un des paramètres fondamentaux de la texture de l’albumen. Ce caractère, essentiel pour la valeur d’utilisation des farines, est fortement lié à l’absence ou à la modification des puroindolines. Afin de mieux comprendre la fonction biologique de ces protéines dans le grain de blé (Triticum aestivum L.), nous avons étudié à quatre stades de développement du grain la localisation subcellulaire des puroindolines par immunocytochimie et les protéomes dans deux lignées de blé quasi-isogéniques pour la dureté. Dès la fin de la cellularisation de l’albumen, les puroindolines sont localisées sur la face interne des membranes vésiculaires et dans les corps protéiques en formation, structures dans lesquelles s’accumulent les protéines de réserve du grain. L’analyse par AFFFF (Asymmetrical Flow Field-Flow Fractionation) des deux lignées Hard et Soft, qui diffèrent essentiellement par l’absence du gène Pina dans la lignée Hard, a montré une corrélation entre la dureté et la taille des polymères de protéines de réserve. L’analyse protéomique des fractions albumines/globulines et amphiphiles des grains en développement a révélé une augmentation des protéines de la machinerie de repliement et de réponse au stress dans la lignée Hard, par rapport à la lignée Soft. Les deux approches méthodologiques utilisées semblent également mettre en évidence une cinétique de développement du grain raccourcie dans la lignée Hard. Ces observations suggèrent que les puroindolines interagissent avec les protéines de réserve du grain et suivent le même routage cellulaire. Elles pourraient être impliquées dans les mécanismes de repliement et d’assemblage des prolamines