Saison d'éclosion, croissance initiale et survie de la morue arctique (Boreogadus saida) en mer de Laptev : impact des polynies

La morue arctique (Boreogadus saida) joue un rôle crucial dans l’écosystème marin arctique. Cette étude décrit pour la première fois la saison d’éclosion, la croissance et la survie larvaire de la morue arctique en mer de Laptev (océan Arctique sibérien). La saison d’éclosion y est hâtive et longue (janvier à juillet) par rapport aux polynies des eaux du Nord et du Nord-Est (mai et juin). La taille à l’âge était plus grande de 4 mm en 2005 (année de faible englacement) qu’en 2003 (année de fort englacement). La survie des larves dépendrait en grande partie des conditions de glace, plus spécialement de l’ampleur et de la durée de l’ouverture des polynies hivernales, caractéristique clé de la mer de Laptev qui démontre de fortes variations interannuelles. En particulier, l’absence de larve survivante pour la période de janvier à la mi-mars 2003 correspondait à l’absence de polynie dans la région d’étude.Arctic cod (Boreogadus saida) plays a crucial role in the marine Arctic ecosystem. For the first time, the hatching season, and the early growth and survival of Arctic cod are described for the Laptev Sea. The hatching season was early and long (January to July) compared to the North Water and Northeast Water Polynyas (May-June). Length at age was 4 mm longer in 2005 (a year of low ice cover) than in 2003 (heavy ice cover). Larval survival could depend mainly on ice conditions, particularly on the extent and duration of opening of winter polynyas, a key feature of the Laptev Sea that shows strong interannual variations. In particular, the absence of surviving larvae for the period of January to mid-March 2003 coincided with the absence of polynya in the study area

Boreogadus saida et Arctogadus glacialis : vie larvaire et juvénile de deux gadidés se partageant l'océan Arctique

Le très abondant Boreogadus saida occupe au sein de l’écosystème marin arctique une place prépondérante, ce qui lui vaut une attention croissante des scientifiques. Arctogadus glacialis, commun dans toutes les mers arctiques, est beaucoup moins étudié. Les deux espèces et leurs jeunes stades cohabitent mais ces derniers sont pratiquement impossibles à différencier. Seuls des outils génétiques, ou une méthode utilisant la taille du noyau de l’otolithe développée dans cette thèse, peuvent distinguer les deux espèces. Ces méthodes d’identification ont permis d’étudier pour la première fois l’écologie des jeunes stades d’Arctogadus et d’estimer la proportion de cette espèce dans des échantillons de gadidés arctiques. À la lumière des observations faites en mer de Beaufort, il apparait que les jeunes Arctogadus ont une abondance environ vingt fois moindre, une taille à l’éclosion supérieure, un taux de croissance similaire, et un taux de mortalité inférieur aux jeunes Boreogadus. Pour Boreogadus, l’hypothèse selon laquelle certaines larves éclosent en hiver près des panaches des fleuves, a été testé, d’abord en comparant la saison d’éclosion dans six régions de l’océan Arctique caractérisées par différents apports d’eau douce. Conformément à cette hypothèse, l’éclosion commence en hiver dans les mers recevant de forts apports fluviaux alors que l’éclosion débute au printemps dans les régions aux apports d’eau douce limités. Les larves qui éclosent en hiver profitent d’une longue saison de croissance leur permettant d’atteindre des tailles pré-hivernales largement supérieures aux larves qui éclosent en été, ce qui favoriserait leur survie. Cette même hypothèse a ensuite été testée en comparant la composition chimique des otolithes de Boreogadus provenant de ces six régions, et les différences observées semblent appuyer l’hypothèse. Les tendances actuelles au devancement de la débâcle, au réchauffement des eaux de surface et à l’augmentation du débit des fleuves pourraient favoriser le recrutement de Boreogadus, et possiblement aussi celui d’Arctogadus. Découle de cette thèse une connaissance accrue de l’écologie de gadidés habitant un océan confronté à une pléthore de changements.The very abundant polar cod (Boreogadus saida) plays a preponderant role in the Arctic marine ecosystem and consequently has received significant attention in recent years. The ice cod (Arctogadus glacialis), a common species in all Arctic seas, is much less studied. Both species co-occur on Arctic continental shelves and their early life stages are often found together in ichthyoplanktonic collections. However, larvae and juveniles of polar cod and ice cod are almost impossible to differentiate. Only genetic tools, or a method using the size of the otolith nucleus developed in this thesis, can distinguish the two species. These identification methods allowed to study for the first time ice cod early life stage ecology and estimate the proportion of this species in Arctic gadids samples. In light of observations made in the Beaufort Sea, it seems that young ice cod are about twenty times less abundant, hatch at a larger size, grow at the same rate, and have a mortality rate inferior to young polar cod. For polar cod, the hypothesis that some larvae hatch in winter near river plumes, was tested, first by comparing the hatching season in six regions of the Arctic characterized by different freshwater inputs. Consistent with this hypothesis, hatching starts in winter in seas receiving large river discharge while hatching starts in spring in regions with limited freshwater inputs. The larvae hatched in winter benefit from a long growth season allowing them to reach larger pre-winter size than larvae hacth in summer, a condition that likely favors their survival. This same hypothesis was further tested by comparing the otolith chemistry of polar cod juveniles from those six regions, and the differences observed seem to support the hypothesis. On-going trends of earlier ice break-up, warmer surface layer, and increased river discharge could favor polar cod, and possibly also ice cod, recruitment. Arise from this thesis an increased knowledge of the ecology of gadids living in an Ocean facing a plethora of changes

Managing Expectations: the European Union and Human Security at the United Nations

This thesis explores the conditions under which the EU is an effective actor at the United Nations in the policy area of human security. Since the late 1990s, the United Nations has been increasingly active in addressing challenges posed by human security concerns. The concept of human security was introduced to emphasize the post-Cold War shift from a state-centred approach to security to an approach focused on the security of individuals. The EU is considered by some as a driving force in the UN policy process and has presented itself as a leader in the promotion of concrete initiatives to address human security challenges. This thesis seeks to examine whether the EU is truly an effective actor at the UN in human security negotiations and aims to identify conditions which influence the EU’s effectiveness. This thesis suggests that the analysis of conditions affecting the EU’s effectiveness at the UN requires the understanding of the ways in which a complex web of actors and institutions interact at three different levels: international, European Union and domestic. Using a multilevel game approach, this thesis examines the willingness of EU actors to work collectively at the UN (internal effectiveness) and the achievements of the EU’s objectives (external effectiveness). This thesis analyzes three cases of human security negotiations: 1) the ban on anti-personnel landmines, 2) the illicit trade in small arms and light weapons (SALW) and 3) the involvement of children in armed conflicts. Factors which have affected the EU’s internal and external effectiveness are identified in each of the case studies. The thesis uses qualitative methods such as expert interviews, documentary analysis and nonparticipant observation. This thesis demonstrates that, at the international level, the commitment of the EU to multilateralism can have an effect on the EU’s effectiveness in human security negotiations. The position of other key UN actors (such as the United States and the G-77) regarding a potential agreement also appears to directly influence EU Member States in achieving their objectives. The thesis argues that the use of consensus in the negotiations process can have a significant impact on the EU’s effectiveness. At the EU level, the analysis reveals that several key EU Member States channelled their efforts to convince their EU partners to act on all three issues. This thesis shows how the role of the EU presidency in coordinating the position of EU Member States can also affect the EU effectiveness in human security negotiations. The support of France, Germany and the United Kingdom, three dominant players in the EU’s Common Foreign and Security Policy, seems also particularly influential in negotiations. Finally, the case studies suggest that domestic politics can directly shape the EU’s effectiveness. Internal negotiations in EU Member States and the involvement of NGOs at the domestic level are two other factors which influence the EU’s effectiveness

Interactions parent-enfant et développement langagier d'enfants négligés âgés de 3,5 ans

Child neglect is a parent's failure to respond to his child's fundamental needs. In this context, language development is particularly vulnerable as it depends on frequent and sensitive parent-child interactions. After having established the prevalence of language delays among neglected children, this study aims to compare dimensions of parent-child interactions in neglectful and non-neglectful dyads and to identify interactional dimensions associated with the language skills of neglected children. Fifteen neglected and 61 nonneglected children aged 3.5 years and their parents participated in the study. Results show that neglected children present significant delays in all language measures. Neglectful parents displayed less responsiveness and less positive affect toward their child than nonneglectful parents. Clinical and research implications conclude this paper