Search

Similar to many freshwater ecosystems, the Laurentian Great Lakes of North America have undergone numerous anthropogenic stressors resulting in considerable loss of biodiversity and habitat. Among Great Lakes fishes, the coregonine sub-family has endured the most extensive declines, including extinction of several species (Coregonus johannae, C. alpenae, and C. kiyi orientalis) and at least 10 instances of local extirpations of other species (C. nigripinnis, C. reighardi, C. zenithicus, C. hoyi, and C. artedi) across all 5 lakes, much of which occurred prior to the 1960s owing to overfishing, interactions with non-indigenous species, and habitat loss. Despite these declines, no federal-, provincial-, or state-mandated actions were ever implemented to conserve coregonine diversity, potentially because so much of the coregonine declines occurred prior to the enactment of federal conservation legislation. Possible explanations for inaction since enactment of that legislation include insufficient data on biological vulnerability or threats, unresolved taxonomy, and limited support from the fishery management agencies and their stakeholders prior to the 2000s. In recent decades, however, several fishery management agencies have undertaken efforts to re-introduce coregonine diversity. These efforts helped lead to development of a science-based framework to restore coregonines that was universally endorsed by fishery managers representing eight U.S. states, four U.S. tribal organizations, and the province of ON, Canada, in May 2018. The basin-wide framework is based on principles of conservation biology and adaptive management. We describe details of its key steps, including planning, restoring, and evaluating, while also describing recent implementation efforts to develop methods, improve available resources, and enhance coordination across the basin. Although our paper describes a regional effort to restore native coregonines, our adaptive-management approach could be used by other multi-agency stakeholders seeking to conserve or restore native fishes. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The amaltheids are restricted temporally to the late Pliensbachian and geographically to the northern part of the northern hemisphere. Amaltheus stokesi is the only species that occurs in all areas of North America where amaltheids are found. The craton north of the Canada–U.S.A. border yields the most diverse amaltheid fauna, including six of the seven taxa known in North America. On Quesnellia and Stikinia, there are no endemic amaltheids, and diversity is low; A. stokesi increases in abundance northwards where, in Stikinia, A. margaritatus makes rare appearances. Wrangellia, with its rich Pliensbachian Tethyan and east Pacific faunas, is almost devoid of amaltheids, but its amaltheid fauna does include two specimens of A. viligaensis, an eastern Russian species that is unknown elsewhere in North America. Cratonal amaltheid faunas have more in common with those of northwest Europe than eastern Eurasia, suggesting that the Arctic and northern North Atlantic constituted the main dispersal route. Paleobiogeographic patterns on the major allochthonous terranes argue against terrane rotation and in support of post-Pliensbachian northward displacement relative to the North American craton. In addition, the presence of western Pacific faunal elements on Wrangellia suggests a more significant longitudinal displacement relative to the craton for this terrane compared to that for Quesnellia and Stikinia. The Chilliwack terrane of southwestern British Columbia is a Pliensbachian paleobiogeographic anomaly.Les Amaltheidés sont restreints dans le temps au Pliensbachien et géographiquement à la partie septentrionale de l'hémisphère Nord. Amaltheus stokesi est la seule espèce qui se trouve dans toutes les régions de l'Amérique du Nord où on retrouve des Amaltheidés. Le craton au nord de la frontière entre le Canada et les États-Unis fournit la faune Amaltheidé la plus diversifiée, incluant six des sept taxons connus en Amérique du Nord. À Quesnellia et Stikinia, il n'y a pas d'Amaltheidés endémiques et la diversité est faible; A. stokesi est de plus en plus abondant vers le nord où, à Stikinia, A. margaritatus apparaît rarement. Wrangellia, avec ses riches faunes tethysiennes et du Pacifique oriental (Pliensbachcien), ne contient presque pas d'Amaltheidés mais sa faune Amaltheidé comprend en effet deux spécimens de A. viligaensis, une espèce russe orientale inconnue ailleurs en Amérique du Nord. Les faunes cratonales Amaltheidés ont plus en commun avec celles de l'Europe du Nord-ouest que celles de l'Eurasie de l'Est, suggérant que l'Arctique et l'Atlantique du Nord septentrional étaient les principales voies de dispersion. Les patrons paléobiogéographiques sur les grands terranes allochtones plaident contre une rotation du terrane et en faveur d'un déplacement relatif vers le nord par rapport au craton, après le Pliensbachien. De plus, la présence d'éléments fauniques du Pacifique ouest sur Wrangellia suggère, pour ce terrane, un déplacement longitudinal plus important par rapport au craton que celui pour Quesnellia et Stikinia. Le terrane de Chilliwack du sud-ouest de la Colombie-Britannique est une anomalie paléobiogéographique du Pliensbachien.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Large igneous provinces (LIPs) are high volume, short duration pulses of intraplate magmatism consisting mainly of flood basalts and their associated plumbing system, but also may include silicic components and carbonatites. Many LIPs have an associated radiating diabase dyke swarm, which typically converges on a cratonic margin, identifies a mantle plume centre, and is linked to breakup or attempted breakup to form that cratonic margin. We hypothesize that every major breakup margin in Canada can be associated with a LIP, and we attempt to identify this LIP. To this end, we focus mainly on high-precision age determinations and the distribution of diabase dyke swarms, which are uniquely valued for preserving the record of magmatic events. The analysis extends from the Phanerozoic to the Neoarchean, but our most complete information is for the Superior craton. There, events at 2.50–2.45, 2.22–2.17, and 2.12–2.08 Ga (LIP and plume) are linked with rifting and breakup or attempted breakup of the south-southeastern, northeastern, and southern margins, respectively. Events at 2.00–1.97 Ga are probably linked with the northern margin (Ungava promontory), while the Circum-Superior event at ca. 1.88 Ga is linked to the north to northwestern margins during a time of Manikewan Ocean closure. Similar linkages for other cratons of North America improve understanding of the breakup history to help identify which blocks were nearest neighbours to Canadian crustal blocks in Precambrian supercontinents. Such interpretations provide a framework for interpreting other geological features of these margins to further test models for the timing and location of breakup. De nombreuses grandes provinces ignées (LIP) résultent de pulsations de courte durée et de grand volume de magmatisme intraplaque. Elles comprennent principalement des basaltes de plateaux et les systèmes de « plomberie »associés; elles peuvent aussi inclure des composantes siliceuses et des carbonatites. De nombreuses LIP ont un essaim de dykes de diabase qui en rayonnent, lequel converge typiquement vers une bordure cratonique, identifie un centre de panache de manteau et est relié à un fractionnement ou à une tentative de fractionnement pour former la bordure du craton. Nous posons l’hypothèse que chaque grand fractionnement au Canada peut être associé à une LIP et nous tentons d’identifier cette LIP. Pour ce faire, nous nous concentrons surtout sur les déterminations d’âge de grande précision et la distribution des essaims de dykes de diabase, lesquels sont très estimés pour leur préservation des données des événements magmatiques. L’analyse s’étend du Phanérozoïque au Néoarchéen, mais nos données les plus complètes concernent le craton du Supérieur. Là, les événements à 2,50–2,45 Ga, 2,22–2,17 Ga et 2,12–2,08 Ga (LIP et panache) sont reliés à la distension et au fractionnement ou à une tentative de fractionnement respectivement des bordures sud–sud-est, nord-est et sud. Les événements qui se sont déroulés vers 2,00–1,97 Ga sont probablement reliés à la bordure nord (promontoire de l’Ungava) alors que l’événement Circum-Supérieur, vers 1,88 Ga est relié aux bordures nord à nord-ouest durant l’époque de la fermeture de l’océan Manikewan. Des liens semblables pour d’autres cratons nord-américains améliorent notre compréhension de l’historique de fractionnement et aident à identifier les blocs qui étaient les plus près des blocs de croûte canadiens dans les supercontinents précambriens. De telles interprétations constituent un cadre pour interpréter d’autres caractéristiques géologiques de ces bordures afin de faire d’autres essais sur les modèles, c’est-à-dire pour le temps et l’endroit du fractionnement. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)