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Full-Text Articles in Life Sciences
Variable Δ15n Diet-Tissue Discrimination Factors Among Sharks: Implications For Trophic Position, Diet And Food Web Models, Jill A. Olin, Nigel E. Hussey, Alice Grgicak-Mannion, Mark W. Fritts, Sabine T. Wintner, Aaron T. Fisk
Variable Δ15n Diet-Tissue Discrimination Factors Among Sharks: Implications For Trophic Position, Diet And Food Web Models, Jill A. Olin, Nigel E. Hussey, Alice Grgicak-Mannion, Mark W. Fritts, Sabine T. Wintner, Aaron T. Fisk
Great Lakes Institute for Environmental Research Publications
The application of stable isotopes to characterize the complexities of a species foraging behavior and trophic relationships is dependent on assumptions of δ15N diet-tissue discrimination factors (∆15N). As ∆15N values have been experimentally shown to vary amongst consumers, tissues and diet composition, resolving appropriate speciesspecific ∆15N values can be complex. Given the logistical and ethical challenges of controlled feeding experiments for determining ∆ 15N values for large and/or endangered species, our objective was to conduct an assessment of a range of reported ∆ 15N values that can hypothetically serve as surrogates for describing the predator-prey relationships of four shark species …
Diatom Assemblages Promote Ice Formation In Large Lakes, N. A. D'Souza, Y. Kawarasaki, J. D. Gantz, R. E. Lee, B. F.N. Beall, Y. M. Shtarkman, Z. A. Koçer, S. O. Rogers, H. Wildschutte, G. S. Bullerjahn, R. M.L. Mckay
Diatom Assemblages Promote Ice Formation In Large Lakes, N. A. D'Souza, Y. Kawarasaki, J. D. Gantz, R. E. Lee, B. F.N. Beall, Y. M. Shtarkman, Z. A. Koçer, S. O. Rogers, H. Wildschutte, G. S. Bullerjahn, R. M.L. Mckay
Great Lakes Institute for Environmental Research Publications
We present evidence for the directed formation of ice by planktonic communities dominated by filamentous diatoms sampled from the ice-covered Laurentian Great Lakes. We hypothesize that ice formation promotes attachment of these non-motile phytoplankton to overlying ice, thereby maintaining a favorable position for the diatoms in the photic zone. However, it is unclear whether the diatoms themselves are responsible for ice nucleation. Scanning electron microscopy revealed associations of bacterial epiphytes with the dominant diatoms of the phytoplankton assemblage, and bacteria isolated from the phytoplankton showed elevated temperatures of crystallization (T c) as high as -3 °C. Ice nucleation-active bacteria were …
Environmental Associations With Gene Transcription In Babine Lake Rainbow Trout: Evidence For Local Adaptation., K. W. Wellband, Daniel D. Heath
Environmental Associations With Gene Transcription In Babine Lake Rainbow Trout: Evidence For Local Adaptation., K. W. Wellband, Daniel D. Heath
Great Lakes Institute for Environmental Research Publications
The molecular genetic mechanisms facilitating local adaptation in salmonids continue to be poorly characterized. Gene transcription is a highly regulated step in the expression of a phenotype and it has been shown to respond to selection and thus may be one mechanism that facilitates the development of local adaptation. Advances in molecular genetic tools and an increased understanding of the functional roles of specific genes allow us to test hypotheses concerning the role of variable environments in shaping transcription at known-function candidate loci. To address these hypotheses, wild rainbow trout were collected in their first summer and subjected to metabolic …
Rates And Controls Of Nitrification In A Large Oligotrophic Lake, Gaston E. Small, George S. Bullerjahn, Robert W. Sterner, Benjamin F.N. Beall, Sandra Brovold, Jacques C. Finlay, Robert M.L. Mckay, Maitreyee Mukherjee
Rates And Controls Of Nitrification In A Large Oligotrophic Lake, Gaston E. Small, George S. Bullerjahn, Robert W. Sterner, Benjamin F.N. Beall, Sandra Brovold, Jacques C. Finlay, Robert M.L. Mckay, Maitreyee Mukherjee
Great Lakes Institute for Environmental Research Publications
Recent discoveries have altered prevailing paradigms concerning the conditions under which nitrification takes place and the organisms responsible for nitrification in aquatic ecosystems. In Lake Superior, nitrate (NO-3) concentrations have increased fivefold in the past century. Although previous evidence indicated that most NO-3 is generated by nitrification within the lake, important questions remain concerning the magnitude and controls of nitrification, and which microbial groups are primarily responsible for this process. We measured water-column nitrification rates in the western basin of Lake Superior during five research cruises from November 2009 to March 2011. Using in situ bottle incubations at 10 depths, …