Non-stationary temporal characterization of the temperature profile of a soil exposed to frost in south-eastern Canada

The objective of this work was to compare time and frequency fluctuations of air and soil temperatures (2-, 5-, 10-, 20- and 50-cm below the soil surface) using the continuous wavelet transform, with a particular emphasis on the daily cycle. The analysis of wavelet power spectra and cross power spectra provided detailed non-stationary accounts with respect to frequencies (or periods) and to time of the structure of the data and also of the relationships that exist between time series. For this particular application to the temperature profile of a soil exposed to frost, both the air temperature and the 2-cm depth soil temperature time series exhibited a dominant power peak at 1-d periodicity, prominent from spring to autumn. This feature was gradually damped as it propagated deeper into the soil and was weak for the 20-cm depth. Influence of the incoming solar radiation was also revealed in the wavelet power spectra analysis by a weaker intensity of the 1-d peak. The principal divergence between air and soil temperatures, besides damping, occurred in winter from the latent heat release associated to the freezing of the soil water and the insulation effect of snowpack that cease the dependence of the soil temperature to the air temperature. Attenuation and phase-shifting of the 1-d periodicity could be quantified through scale-averaged power spectra and time-lag estimations. Air temperature variance was only partly transferred to the 2-cm soil temperature time series and much less so to the 20-cm soil depth

Changes in Isotopic Niches across Stages of the Annual Cycle in the Arctic Tern (Sterna paradisaea)

 Arctic Terns (Sterna paradisaea) are iconic seabirds of polar latitudes, whose successful reproduction is thought to depend on local food supplies near breeding colonies. We used stable isotopes of carbon and nitrogen in eggs, blood, and feathers of terns breeding in the Canadian High Arctic to compare their isotopic niche between life history stages and between two years. The isotopic niche of terns was smaller during incubation than during pre-breeding or winter. Over two breeding seasons, isotopic profiles of Arctic Terns suggested the high importance of local, exogenous nutrient supplies to form eggs (i.e., an income breeding strategy). Our results illustrate that using stable isotopes to assess the niche of a seabird population during critical periods of its annual cycle could be an essential tool in determining the influence that local forage conditions have on breeding decisions, especially for species that mostly rely on exogenous sources of nutrients and energy for egg production. La sterne arctique (Sterna paradisaea) est un oiseau de mer emblématique des latitudes polaires, dont la reproduction réussie dépendrait de l’approvisionnement en aliments à proximité des colonies de nidification. Nous avons utilisé les isotopes stables du carbone et de l’azote provenant des oeufs, du sang et des plumes des sternes se reproduisant dans l’Extrême-Arctique canadien pour comparer leur niche isotopique entre divers stades de leur cycle biologique ainsi qu’entre deux années différentes. La niche isotopique des sternes était plus petite pendant l’incubation qu’avant la reproduction ou que pendant l’hiver. Au cours des deux saisons de reproduction, les profils isotopiques des sternes arctiques ont laissé entrevoir la grande importance d’approvisionnements en nutriments locaux et exogènes pour la formation des oeufs (soit une stratégie de reproduction à approvisionnement). Nos résultats illustrent que l’utilisation des isotopes stables pour évaluer la niche de la population d’oiseaux de mer pendant les périodes critiques de leur cycle annuel pourrait constituer un outil essentiel pour déterminer l’influence qu’ont les conditions d’alimentation locales sur les décisions de reproduction, surtout pour les espèces qui dépendent de sources d’énergie et de nutriments exogènes pour la production des oeufs

Quorum Sensing Signal Production and Microbial Interactions in a Polymicrobial Disease of Corals and the Coral Surface Mucopolysaccharide Layer

Black band disease (BBD) of corals is a complex polymicrobial disease considered to be a threat to coral reef health, as it can lead to mortality of massive reef-building corals. The BBD community is dominated by gliding, filamentous cyanobacteria with a highly diverse population of heterotrophic bacteria. Microbial interactions such as quorum sensing (QS) and antimicrobial production may be involved in BBD disease pathogenesis. In this study, BBD (whole community) samples, as well as 199 bacterial isolates from BBD, the surface mucopolysaccharide layer (SML) of apparently healthy corals, and SML of apparently healthy areas of BBD-infected corals were screened for the production of acyl homoserine lactones (AHLs) and for autoinducer-2 (AI-2) activity using three bacterial reporter strains. AHLs were detected in all BBD (intact community) samples tested and in cultures of 5.5% of BBD bacterial isolates. Over half of a subset (153) of the isolates were positive for AI-2 activity. AHL-producing isolates were further analyzed using LC-MS/MS to determine AHL chemical structure and the concentration of (S)-4,5-dihydroxy-2,3-pentanedione (DPD), the biosynthetic precursor of AI-2. C6-HSL was the most common AHL variant detected, followed by 3OC4-HSL. In addition to QS assays, 342 growth challenges were conducted among a subset of the isolates, with 27% of isolates eliciting growth inhibition and 2% growth stimulation. 24% of BBD isolates elicited growth inhibition as compared to 26% and 32% of the bacteria from the two SML sources. With one exception, only isolates that exhibited AI-2 activity or produced DPD inhibited growth of test strains. These findings demonstrate for the first time that AHLs are present in an active coral disease. It is possible that AI-2 production among BBD and coral SML bacteria may structure the microbial communities of both a polymicrobial infection and the healthy coral microbiome

Long-term Declines in the Size of Northern Fulmar (Fulmarus glacialis) Colonies on Eastern Baffin Island, Canada

We censused three colonies of Northern Fulmars (Fulmarus glacialis) along eastern Baffin Island, Canada, that were estimated to support 155 000 breeding pairs in 1973, but had not been adequately counted since then. The colonies were surveyed in July and August 2018 using photographs taken from a helicopter or a drone. The combined estimated colony sizes were 36 500 pairs, much smaller than historical estimates. Although the 1973 estimates were coarse, this difference represents an apparent 3+% annual decline in numbers at each colony over approximately four decades or more than 87% over three generations (66 years). Several factors may be contributing to these declines, including changes in winter food supplies and the susceptibility of fulmars to fisheries bycatch. We recommend efforts to survey the remaining major fulmar colonies in Arctic Canada to assess the overall population size and trends, and allow for further analyses of potential population drivers.Nous avons recensé trois colonies de fulmars boréaux (Fulmarus glacialis) sur la côte est de l’île de Baffin, au Canada. Selon des estimations réalisées en 1973, 155 000 couples reproducteurs y nichaient, mais aucun dénombrement adéquat n’avait été effectué depuis. Les colonies ont été recensées en juillet et en août 2018 au moyen de photographies prises à partir d’un hélicoptère ou d’un drone. La taille combinée des colonies a été estimée à 36500 couples, soit un nombre beaucoup moins élevé que les estimations précédentes. Bien que les estimations de 1973 étaient des estimations grossières, cette différence représente une baisse annuelle apparente de plus de 3 % à chacune des colonies sur environ quatre décennies, soit plus de 87 % sur trois générations (66 ans). Ces diminutions peuvent être attribuables à plusieurs facteurs, dont les changements caractérisant les approvisionnements en nourriture pendant l’hiver et la susceptibilité des fulmars à faire l’objet de captures accessoires. Nous recommandons que des efforts soient faits pour recenser les grandes colonies de fulmars qui restent dans l’Arctique canadien afin d’évaluer la taille globale de la population et les tendances la caractérisant, ainsi que pour pousser plus loin l’analyse des facteurs susceptibles d’avoir un effet sur leurs populations

Partnerships and Public Service: Normative Issues for Journalists in Converged Newsrooms

As media companies test and implement newsroom “convergence,” growing numbers of journalists are producing content not only for their own employer but also for other media outlets with which that employer has a business relationship. This article, based on case studies in four converged news markets, explores journalists’ perceptions of normative pressures in this new media environment, particularly in relation to the overarching concept of public service. The findings suggest that although journalists do not see convergence itself as posing significant ethical problems, they do raise concerns related to specific components of public service, including a devotion to accuracy, an avoidance of sensationalism, and independence from economic pressures

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 large

Female and male Leach\u27s Storm Petrels (Hydrobates leucorhous) pursue different foraging strategies during the incubation period

Reproduction in procellariiform birds is characterized by a single egg clutch, slow development, a long breeding season and obligate biparental care. Female Leach\u27s Storm Petrels Hydrobates leucorhous, nearly monomorphic members of this order, produce eggs that are between 20 and 25% of adult bodyweight. We tested whether female foraging behaviour differs from male foraging behaviour during the ~ 44-day incubation period across seven breeding colonies in the Northwest Atlantic. Over six breeding seasons, we used a combination of Global Positioning System and Global Location Sensor devices to measure characteristics of individual foraging trips during the incubation period. Females travelled significantly greater distances and went farther from the breeding colony than did males on individual foraging trips. For both sexes, the longer the foraging trip, the greater the distance. Independent of trip duration, females travelled farther, and spent a greater proportion of their foraging trips prospecting widely, as defined by behavioural categories derived from a hidden Markov Model. For both sexes, trip duration decreased with date. Sex differences in these foraging metrics were apparently not a consequence of morphological differences or spatial segregation. Our data are consistent with the idea that female foraging strategies differed from male foraging strategies during incubation in ways that would be expected if females were still compensating for egg formation