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Quantifying nutritional sources for Mysis diluviana will help to clarify the basis for production in lakes with Mysis and improve models of migration-driven nutrient and contaminant transport. We sampled Mysis, plankton, and benthos across Lake Superior using a stratified-random design that provided a statistically valid representation of the lake across depths. We then estimated nutritional contributions to Mysis using stable isotope ratios of Mysis, zooplankton, Bythotrephes, Diporeia, oligochaetes, and detritus in a multiple-source, dual-isotope mixing model. Lake-wide, small ( L'analyse quantitative des sources de nourriture de Mysis diluviana va aider a clarifier la base de la production dans les lacs a Mysis et ameliorer les modeles de transport des nutriments et des contaminants bases sur la migration. Nous avons echantillonne les Mysis, le plancton et le benthos a travers le lac Superieur selon un plan stratifie-aleatoire qui fournit une representation statistiquement valide du lac en fonction des profondeurs. Nous avons ensuite estime les contributions alimentaires aux Mysis en utilisant les rapports d'isotopes stables des Mysis, du zooplancton, de Bythotrephes, de Diporeia, des oligochetes et du detritus dans un modele de melange de deux isotopes a sources multiples. A l'echelle du lac, les petits ( [Traduit par la Redaction], Introduction Understanding the role of Mysis in lake food webs continues to be an important and fertile area of research. In the Laurentian Great Lakes, Mysis diluviana (formerly Mysis relicta) [...]

The freshwater amphipod Diporeia is a crucial part of the food web in the Laurentian Great Lakes, but has faced serious declines correlated with the invasion of zebra mussels (Dreissena polymorpha), except in Lake Superior, which has seen an increase in Diporeia abundance. Speculation on the mechanisms causing changes in Diporeia densities has not included the possibility of evolutionarily distinct lineages of Diporeia within the Great Lakes. In this study, we use cytochrome c oxidase subunit I (COI) DNA sequence data to investigate the evolutionary history of Lake Superior Diporeia relative to the other Great Lakes and consider potential population structuring within Lake Superior based upon depth or geography. Our analyses reveal that Lake Superior Diporeia represent a distinct lineage that diverged from populations of the other lakes at least several hundred thousand years ago. F statistics show that two localities within Lake Superior were significantly differentiated from all other locales, but analysis of molecular variance did not find significant structure based on depth or geography. Genetic diversity within Lake Superior was not correlated with depth, although abundance was significantly negatively correlated with increasing depth. L'amphipode d'eau douce Diporeia est un maillon essentiel du reseau alimentaire des Grands Lacs laurentiens; il a cependant subi de serieux declins en rapport avec l'invasion de la moule zebree (Dreissena polymorpha), excepte au lac Superieur ou la population de Diporeia a cru en abondance. Les speculations entourant les mecanismes qui ont provoque les changements de densite des Diporeia n'ont pas pris en compte la possibilite de l'existence de lignees evolutives distinctes de Diporeia au sein des Grands Lacs. Nous utilisons, dans notre etude, les donnees de sequencage de l'ADN de cytochrome c oxydase sous-unite I (COI) pour examiner l'histoire evolutive des Diporeia du lac Superieur en rapport avec ceux des autres Grands Lacs et pour evaluer la possibilite de l'existence d'une structure de la population du lac Superieur en fonction de la profondeur ou de la geographie. Nos analyses revelent que les Diporeia du lac Superieur representent une ligne distincte qui a diverge des populations des autres Grands Lacs il y a au moins plusieurs centaines de milliers d'annees. La statistique F montre que deux sites au lac Superieur se distinguent significativement de tous les autres sites, mais une analyse de la variance moleculaire ne discerne pas de structure significative basee sur la profondeur ou la geographie. La diversite genetique au sein du lac Superieur n'est pas en correlation avec la profondeur, bien que l'abondance soit en correlation negative significative avec l'augmentation de la profondeur. [Traduit par la Redaction], Introduction The amphipod genus Diporeia Bousfield is restricted to deep, glacial relict lakes in northern North America (Bousfield 1989). In the Laurentian Great Lakes, Diporeia (6-9 mm long as adults) [...]

Abstract: In an investigation of the spatial characteristics of Laurentian Great Lakes food webs, we examined the trophic relationship between benthic amphipods (Diporeia) and plankton in Lake Superior. We analyzed [...]

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