Land-Based Pollution in the Arctic Ocean: Canadian Actions in a Regional and Global Context

The occurrence of high concentrations of anthropogenic contaminants in the Arctic environment has been a concern for many years. The present overview of the current threats of pollutants from atmospheric, oceanic, river, and local pathways uses results from recent national, pan-Arctic, and international reports to emphasize the need to address issues arising from climate change, particularly the effect of changing weather patterns on contaminant transportation via both waterways and the atmosphere. Regional and international actions over the past two decades attempting to manage pollutants in the Arctic environment from landbased sources have produced recommendations that focus primarily on increasing cooperation in research and monitoring activities, not only among the Arctic governments themselves, but also including the interests and resources of non-polar countries. Our Canadian perspective on the domestic and circumpolar context of the issue, with regard to mechanisms exerting immediate control on the spread of contaminants, describes national programs and policies that are important to the Canadian North and to the Arctic community as a whole. All levels of Canadian government, as well as foreign governments, have joined in working towards safeguarding the Arctic and other marine environments. Prioritization of concerns is an important approach to tackling the numerous current issues related to the spread of contaminants in the Arctic environment. The government needs to give increased priority to the North, and that action needs to be taken in partnership with local communities and pursued at the regional, national, and international levels.La présence de fortes concentrations de contaminants anthropogéniques dans l’environnement arctique est une source d’inquiétude depuis des années. Le présent aperçu des menaces actuelles découlant des polluants provenant de l’atmosphère, des océans, des fleuves et rivières ainsi que de la région s’appuie sur les résultats de récents rapports d’envergure nationale, panarctique et internationale pour faire ressortir la nécessité de résoudre les enjeux résultant du changement climatique, plus particulièrement l’effet de la situation météorologique changeante sur le transport des contaminants, tant par les cours d’eau que par l’atmosphère. Ces vingt dernières années, les mesures prises à l’échelle régionale et internationale pour tenter de gérer les polluants de sources terrestres dans l’environnement arctique ont donné lieu à des recommandations qui visent principalement une coopération accrue sur le plan des activités de recherche et de surveillance, non seulement au sein des gouvernements arctiques mêmes, mais aussi en faisant appel aux intérêts et aux ressources des pays non polaires. Notre perspective canadienne sur le contexte intérieur et circumpolaire à propos de cette question, en ce qui a trait aux mécanismes qui exercent un contrôle immédiat sur la propagation des contaminants, décrit des politiques et des programmes nationaux qui sont importants aux yeux des collectivités du Nord canadien et de l’Arctique dans l’ensemble. Tous les échelons de gouvernement canadien, de même que de gouvernements étrangers, travaillent de concert pour protéger l’environnement de l’Arctique et d’autres environnements marins. La priorisation des préoccupations constitue une manière importante de s’attaquer aux nombreux enjeux actuels relatifs à la propagation des contaminants dans l’environnement arctique. Le gouvernement doit accorder une priorité accrue au Nord, et cela doit se faire en collaboration avec les collectivités de la région, en plus de s’étendre aux échelons régionaux, nationaux et internationaux

Hierarchical analysis of genetic structure in the habitat-specialist Eastern Sand Darter (Ammocrypta pellucida)

Quantifying spatial genetic structure can reveal the relative influences of contemporary and historic factors underlying localized and regional patterns of genetic diversity and gene flow - important considerations for the development of effective conservation efforts. Using 10 polymorphic microsatellite loci, we characterize genetic variation among populations across the range of the Eastern Sand Darter (Ammocrypta pellucida), a small riverine percid that is highly dependent on sandy substrate microhabitats. We tested for fine scale, regional, and historic patterns of genetic structure. As expected, significant differentiation was detected among rivers within drainages and among drainages. At finer scales, an unexpected lack of within-river genetic structure among fragmented sandy microhabitats suggests that stratified dispersal resulting from unstable sand bar habitat degradation (natural and anthropogenic) may preclude substantial genetic differentiation within rivers. Among-drainage genetic structure indicates that postglacial (14kya) drainage connectivity continues to influence contemporary genetic structure among Eastern Sand Darter populations in southern Ontario. These results provide an unexpected contrast to other benthic riverine fish in the Great Lakes drainage and suggest that habitat-specific fishes, such as the Eastern Sand Darter, can evolve dispersal strategies that overcome fragmented and temporally unstable habitats

Mixed evidence for reduced local adaptation in wild salmon resulting from interbreeding with escaped farmed salmon: complexities in hybrid fitness

Interbreeding between artificially-selected and wild organisms can have negative fitness consequences for the latter. In the Northwest Atlantic, farmed Atlantic salmon recurrently escape into the wild and enter rivers where small, declining populations of wild salmon breed. Most farmed salmon in the region derive from an ancestral source population that occupies a nonacidified river (pH 6.0–6.5). Yet many wild populations with which escaped farmed salmon might interbreed inhabit acidified rivers (pH 4.6–5.2). Using common garden experimentation, and examining two early-life history stages across two generations of interbreeding, we showed that wild salmon populations inhabiting acidified rivers had higher survival at acidified pH than farmed salmon or F1 farmed-wild hybrids. In contrast, however, there was limited evidence for reduced performance in backcrosses, and F2 farmed-wild hybrids performed better or equally well to wild salmon. Wild salmon also survived or grew better at nonacidified than acidified pH, and wild and farmed salmon survived equally well at nonacidified pH. Thus, for acid tolerance and the stages examined, we found some evidence both for and against the theory that repeated farmed-wild interbreeding may reduce adaptive genetic variation in the wild and thereby negatively affect the persistence of depleted wild populations

Using ecosystem-services assessments to determine trade-offs in ecosystem-based management of marine mammals

The goal of ecosystem-based management (EBM) is to support a sustainable and holistic multisectored management approach, and is recognized in a number of international policy frameworks. However, it remains unknown how these goals should be linked to assessments and management plans for marine fauna, such as mammals and fish stocks. It appears particularly challenging to carry out trade-off analyses of various ocean uses without a framework that integrates knowledge of environmental, social, and economic benefits derived from nonstationary marine fauna. We argue this gap can be filled by applying a version of the ecosystem-service approach at the population level of marine fauna. To advance this idea, we used marine mammals as a case study to demonstrate what indicators could operationalize relevant assessments and deliver an evidence base for the presence of ecosystem services and disservices derived from marine mammals. We found indicators covering common ecosystem service categories feasible to apply; examples of indicator data are already available in the literature for several populations. We encourage further exploration of this approach for application to marina fauna and biodiversity management, with the caveat that conceptual tensions related to the use of the ecosystem service concept itself needs to be addressed to ensure acceptance by relevant stakeholders