Geopolitics and shipping development in the Arctic

With the impact of climate change and the melting of sea ice, many narratives about the impending boom in Arctic transit shipping have emerged. Analyses also highlight the potential conflicts between Russia and Canada, on the one hand, claiming sovereignty over their respective Arctic passage, and the United States, the European Union and possibly Asian States, on the other hand, asserting to various degrees the international straits status for these Arctic passages. These geopolitical conflicts for the control of transit shipping and the Arctic straits have not taken place because of a very limited traffic volume stemming for the limited attraction of these Arctic routes for transit. Traffic is indeed expanding, but it is destinational traffic, under the firm control of the port State. The possible development of transshipment hubs for Arctic shipping could change this picture

Caractérisation de la biodiversité à l'aide d'une analyse génétique chez les moules d'eau douce du genre Pyganodon (Unionidae) dans le nord est de l'Amérique du Nord

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal

La réunification allemande à Bonn, Washington et Moscou : les mémoires politiques et le processus menant à l'unité de l'Allemange de 1989-1990

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal

Les impacts de la dispersion historique sur la variabilité génétique à différentes échelles spatiales : connaître l'histoire pour mieux comprendre le présent

La variabilité génétique actuelle est influencée par une combinaison complexe de variables historiques et contemporaines. Dès lors, une interprétation juste de l’impact des processus actuels nécessite une compréhension profonde des processus historiques ayant influencé la variabilité génétique. En se basant sur la prémisse que des populations proches devraient partager une histoire commune récente, nombreuses études, effectuées à petite échelle spatiale, ne prennent pas en considération l’effet potentiel des processus historiques. Cette thèse avait pour but de vérifier la validité de cette prémisse en estimant l’effet de la dispersion historique à grande et à petite échelle spatiale. Le premier volet de cette thèse avait pour but d’évaluer l’impact de la dispersion historique sur la répartition des organismes à grande échelle spatiale. Pour ce faire, les moules d’eau douce du genre flotteurs (Pyganodon spp.) ont servies de modèle biologique. Les moules d'eau douce se dispersent principalement au stade larvaire en tant que parasites des poissons. Une série de modèles nuls ont été développés pour évaluer la co-occurrence entre des parasites et leurs hôtes potenitels. Les associations distinctes du flotteur de Terre-Neuve (P. fragilis) avec des espèces de poissons euryhalins permettent d’expliquer sa répartition. Ces associations distinctes ont également pu favoriser la différenciation entre le flotteur de Terre-Neuve et son taxon soeur : le flotteur de l’Est (P. cataracta). Cette étude a démontré les effets des associations biologiques historiques sur les répartitions à grande échelle spatiale. Le second volet de cette thèse avait pour but d’évaluer l’impact de la dispersion historique sur la variabilité génétique, à petite échelle spatiale. Cette fois, différentes populations de crapet de roche (Ambloplites rupestris) et de crapet soleil (Lepomis gibbosus), dans des drainages adjacents ont servies de modèle biologique. Les différences frappantes observées entre les deux espèces suggèrent des patrons de colonisation opposés. La faible diversité génétique observée en amont des drainages et la forte différenciation observée entre les drainages pour les populations de crapet de roche suggèrent que cette espèce aurait colonisé les drainages à partir d'une source en aval. Au contraire, la faible différenciation et la forte diversité génétique observées en amont des drainages pour les populations de crapet soleil suggèrent une colonisation depuis l’amont, induisant du même coup un faux signal de flux génique entre les drainages. La présente étude a démontré que la dispersion historique peut entraver la capacité d'estimer la connectivité actuelle, à petite échelle spatiale, invalidant ainsi la prémisse testée dans cette thèse. Les impacts des processus historiques sur la variabilité génétique ne sont pas faciles à démontrer. Le troisième volet de cette thèse avait pour but de développer une méthode permettant de les détecter. La méthode proposée est très souple et favorise la comparaison entre la variabilité génétique et plusieurs hypothèses de dispersion. La méthode pourrait donc être utilisée pour comparer des hypothèses de dispersion basées sur le paysage historique et sur le paysage actuel et ainsi permettre l’évaluation des impacts historiques et contemporains sur la variabilité génétique. Les performances de la méthode sont présentées pour plusieurs scénarios de simulations, d’une complexité croissante. Malgré un impact de la différentiation globale, du nombre d’individus ou du nombre de loci échantillonné, la méthode apparaît hautement efficace. Afin d’illustrer le potentiel de la méthode, deux jeux de données empiriques très contrastés, publiés précédemment, ont été ré analysés. Cette thèse a démontré les impacts de la dispersion historique sur la variabilité génétique à différentes échelles spatiales. Les effets historiques potentiels doivent être pris en considération avant d’évaluer les impacts des processus écologiques sur la variabilité génétique. Bref, il faut intégrer l’évolution à l’écologie.Current genetic variability depends on a complex combination of historical and contemporary factors. Therefore, an unbiased interpretation of the impact of current processes requires a deep understanding of historical processes that shaped genetic variability. Based on the premise that spatially close populations should share a common recent history, many studies conducted at small spatial scale do not take into account the effect of historical processes. This thesis aims to verify the validity of this assumption by estimating the effect of historical dispersion at large and small spatial scales. The aim of the first part of this thesis was to evaluate the impact of the historical dispersion on the distribution of organisms, at large spatial scale. The freshwater mussels of the genus Floater (Pyganodon spp.) were used as biological model. The dispersal of freshwater mussels occurs when larvae parasitize fish. Also, a series of null models has been developed to evaluate the co-occurrence between parasites and their hosts. The distinct associations of the Newfoundland floater (P. fragilis) with euryhaline fish species can explain its distribution. These associations also promoted differentiation with its sister taxon: the Eastern floater (P. cataracta). This study demonstrated the effects of historical biological associations on the current distribution of species at a large spatial scale. The aim of the second part of this thesis was to evaluate the impact of historical dispersal on the genetic variability, at small spatial scale. This time populations of rock bass (Ambloplites rupestris) and sunfish (Lepomis gibbosus) in adjacent drainages were used as biological model. The striking differences observed between the two species suggest opposing colonization patterns. Rock bass have colonized the drainage from a downstream source, resulting in low genetic diversity upstream and a strong differentiation between drainages. However, the sunfish have colonized the system from upstream, resulting in a high genetic diversity and low differentiation upstream, inducing at the same time a false signal of gene flow between drainages. The present study shows that the historical dispersion may hinder the ability to estimate the actual connectivity at small spatial scale, thus invalidating the premise tested in this thesis. The impacts of historical processes on genetic variability are not easy to demonstrate. The aim of the third part of this thesis was to develop a method to facilitate their detection. The proposed method is very flexible and facilitates the comparison between genetic variability and multiple dispersal hypotheses. The method could be used to compare dispersal hypotheses based on the historic or the current landscape and allow the assessment of historical and contemporary processes on genetic variability. The performances of the method are presented in several simulation scenarios, of increasing complexity. Despite an overall impact of differentiation, the number of individuals or the number of loci sampled, the method is highly effective. To illustrate the potential of the method, two contrasted data sets from previously published studies, were re-analyzed. This thesis demonstrates the impacts of historical dispersal on genetic variability at different spatial scales. Potential historical effects must be taken into account before assessing the impacts of ecological processes on genetic variability. In short, we must bridge the gap between ecology and evolution

Rebelle devant les extrêmes : Paul Levi, une biographie politique

Cette thèse de doctorat est une biographie politique de Paul Levi, militant marxiste qui a fait carrière en Allemagne durant la période de l’entre-deux-guerres. Dès 1914, Levi incarne un courant radical à l’intérieur du Parti social-démocrate d’Allemagne (SPD). Il dénonce, entre autres, aux côtés de Rosa Luxemburg l’appui du parti à l’effort militaire national. Levi s’inspire également de Lénine qu’il rencontre pour la première fois en Suisse en 1916-1917. Lorsqu’il prend les commandes du Parti communiste d’Allemagne (KPD) en 1919, Levi dirige celui-ci d’une main de fer, selon le concept du « centralisme démocratique ». Il fait également tout en son pouvoir pour faire éclater la révolution ouvrière en Allemagne afin d’installer une dictature du prolétariat qui exclurait toutes les classes non ouvrières du pouvoir. En ce sens, Levi imagine un État socialiste semblable à celui fondé par Lénine en Russie en 1917. Contrairement à l’historiographie traditionnelle, notre thèse montre conséquemment que Levi n’était guère un « socialiste démocrate ». Il était plutôt un militant marxiste qui, par son radicalisme, a contribué à diviser le mouvement ouvrier allemand ce qui, en revanche, a fragilisé la république de Weimar. Cette thèse fait également ressortir le caractère résolument rebelle de Paul Levi. Partout où il passe, Levi dénonce les politiques bourgeoises des partis non-ouvriers, mais aussi celles de la majorité des organisations dont il fait partie, c’est-à-dire les partis ouvriers de la république de Weimar et le Reichstag. Son tempérament impulsif fait de lui un homme politique isolé qui, d’ailleurs, se fait de nombreux ennemis. En 1921, à titre d’exemple, il se brouille avec d’importants bolcheviques, ce qui met fin à sa carrière au sein du KPD. Les communistes voient désormais en lui un ennemi de la classe ouvrière et mènent contre lui de nombreuses campagnes diffamatoires. Levi, de son côté, dénonce ouvertement la terreur stalinienne qui, selon lui, est en train de contaminer le mouvement communiste européen. Notre travail montre également que Levi, cette fois en tant qu’avocat juif, lutte corps et âme contre les nazis. En 1926, dans le cadre d’une commission d’enquête publique du Reichstag chargée de faire la lumière sur des meurtres politiques commis en Bavière, il tente par tous les moyens d’inculper certains criminels nazis. Levi est conséquemment la cible de la presse antisémite allemande. Il refuse toutefois de céder à l’intimidation et choisit plutôt de poursuivre en justice quelques-uns des plus importants membres du Parti nazi, dont Alfred Rosenberg et Hitler lui-même, en plus de forcer de nombreux autres nazis à comparaître devant la commission d’enquête du Reichstag. Bref, si ce travail se veut critique envers la pensée révolutionnaire de Levi, il souligne aussi l’intégrité politique de cet homme dont les convictions sont demeurées inébranlables face aux dérives criminelles des extrêmes idéologiques de son époque.This Ph.D. thesis is a political biography of Paul Levi, a German Marxist of the interwar period. Already in 1914, Levi embodied a radical faction within the Social Democratic Party of Germany (SPD). Alongside Rosa Luxemburg, the leader of this same left wing, he is contesting, above all, the party’s participation in the national war effort. But Levi is also inspired by Lenin, who he met in Switzerland in 1916-1917. In fact, when taking over the leadership of the German Communist Party (KPD) in March 1919, Levi ruled with an iron fist according to the theory of “democratic centralism”. As Lenin has done in Russia in October 1917, Levi also did everything in his power to promote a workers’ revolution in Germany in order to set in power a dictatorship of the proletariat, which would exclude all other social classes from sitting in the government. Consequently, in opposition to traditional historiography, this thesis shows that Levi was not a “democratic Socialist” of the Luxemburg school, but rather a Marxist whose political thought resembled that of the Bolsheviks. In fact, his action contributed to further weaken an already frail Weimar Republic and all its democratic institutions. This study also shows that Levi’s outstanding career was in large part the result of his rebellious character. Throughout his life, Levi consistently denounced the bourgeois politics of the non-workers’ parties, but he also systematically went against the majority within the political organizations in which he took part: the workers’ parties and the Reichstag. His impulsive nature set him apart as a solitary politician. In fact, Levi had many enemies. In 1921, he ran afoul of major Bolshevik leaders, which caused him to lose the leadership of the KPD. The Communists subsequently saw him as an enemy of the working class, slandering him in the press and in the Reichstag. Levi denounced, for his part, the Stalinist terror and made a mockery of the KPD, which had become, according to him, no more than a Soviet puppet. But this thesis also reveals that Levi, as a Jewish lawyer, led a major political campaign against the Nazis. In 1926, for example, as he served on a Reichstag public commission investigating Bavarian political assassinations, he tried by all possible means to charge important Nazis with murder. The Nazi press replied with a vicious anti-Semitic press campaign against him. Levi, however, refused to kneel before such intimidation and rather chose to sue important Nazi leaders, such as Alfred Rosenberg and Hitler himself before the court, in addition to summoning many others before the above-mentioned Reichstag commission. In the end, despite the fact that this study very critically evaluates Levi’s ideology, it praises his political integrity, which remained unshakable though faced with adversity and the criminal drift of the political extremes of the interwar period

Impacts of intraguild predation on Arctic copepod communities

Communities of large copepods form an essential hub of matter and energy fluxes in Arctic marine food webs. Intraguild predation on eggs and early larval stages occurs among the different species of those communities and it has been hypothesized to impact its structure and function. In order to better understand the interactions between dominant copepod species in the Arctic, we conducted laboratory experiments that quantified intraguild predation between the conspicuous and omnivorous Metridia longa and the dominant Calanus hyperboreus. We recorded individual egg ingestion rates for several conditions of temperature, egg concentration, and alternative food presence. In each of these experiments, at least some females ingested eggs but individual ingestion rates were highly variable. The global mean ingestion rate of M. longa on C. hyperboreus eggs was 5.8 eggs ind−1 d−1, or an estimated 37% of M. longa daily metabolic need. Among the different factors tested and the various individual traits considered (prosome length, condition index), only the egg concentration had a significant and positive effect on ingestion rates. We further explored the potential ecological impacts of intraguild predation in a simple 1D numerical model of C. hyperboreus eggs vertical distribution in the Amundsen Gulf. Our modeling results showed an asymmetric relationship in that M. longa has little potential impact on the recruitment of C. hyperboreus (<3% egg standing stock removed by IGP at most) whereas the eggs intercepted by the former can account for a significant portion of its metabolic requirement during winter (up to a third)

Strong water stratification provides a refuge for rainbow smelt larvae Osmerus mordax in a sub-arctic estuary (Lake Melville, Labrador)

Estuaries provide nurseries for early life stages of fish that rely on the interaction between fresh- and saltwater. The 250 km long Lake Melville spans 2100 km2 and is the largest estuary of Labrador (northeastern Canada). This sub-arctic fjard hosts freshwater, anadromous, and marine fishes on which depend marine mammals and seabirds, but also coastal communities. Yet, how different fish species and life stages use the estuary as a habitat, in particular the importance of the low salinity surface layer for the development of fish larvae, remains unknown. By pairing seasonal hydroacoustic surveys conducted in summers 2018–2019 and winters 2019–2020 with net sampling and environmental DNA (eDNA) analyses, we test the hypothesis that the strong water stratification prevailing in upper Lake Melville provides a nursery for early life stages of fish, where they are protected from their predators. Ichthyoplankton aggregated just above and at the pycnocline, in the low salinity surface layer down to 25 m. Most adult pelagic fish occupied the bottom waters below the sharp pycnocline, although some ventured in the low salinity surface layer. Ten species of adult fish were captured in gill and fyke nets and 53 species were detected with eDNA. Larvae of rainbow smelt (Osmerus mordax) were ubiquitous in the surface layer in July and August and represented 100% of the ichthyoplankton assemblage sampled during these months. No fish larvae were detected in winter (February). We conclude that the low salinity surface layer provides a refuge for rainbow smelt larvae, a key forage species in the estuary. This study provides baseline information from which to assess future changes in biodiversity and distribution of fish in the Lake Melville estuary. It further supports the use of eDNA as a complementary tool for monitoring fish diversity in sub-arctic estuaries

Southern Ocean food-webs and climate change:A short review and future directions

Food-webs are a critical feature of ecosystems and help us understand how communities will respond to climate change. The Southern Ocean is facing rapid and accelerating changes due to climate change. Though having evolved in an isolated and somewhat extreme environment, Southern Ocean biodiversity and food-webs are among the most vulnerable. Here, we review 1) current knowledge on Southern Ocean food-webs; 2) methods to study food-webs; 3) assessment of current and future impacts of climate change on Southern Ocean food-webs; 4) knowledge gaps; and 5) the role of Early Career Researchers (ECRs) in future studies. Most knowledge on Southern Ocean food-webs come from the pelagic environment, both at macro- and microbial levels. Modelling and diet studies of individual species are major contributors to the food-web knowledge. These studies revealed a short food-web, predominantly sustained by Antarctic Krill (Euphausia superba). Additionally, alternative pathways exist, involving other krill species, fish, and squid, which play equally important roles in connecting primary producers with top predators. Advantages and disadvantages of several techniques used to study Southern Ocean food-webs were identified, from the classical analyses of stomach contents, scats, or boluses to the most recent approaches such as metabarcoding and trophic-biomarkers. Observations show that climate change can impact the food-web in different ways. As an example, changes to smaller phytoplankton species can lengthen the food-web, increasing assimilation losses and/or changing nutrient cycles. Future studies need to focus on the benthic-dominated food-webs and the benthopelagic coupling. Furthermore, research during the winter season and below the ice-shelves is needed as these areas may play a crucial role in the functioning of this ecosystem. ECRs can play a significant role in advancing the study of Southern Ocean food-webs due to their willingness for interdisciplinary collaboration and proficiency in employing various methodologies, contributing to the construction of high-resolution food-webs