Uptake of stable N isotopes by Myriophyllum spicatum is not selective |
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Authors: | Risa A Cohen Andrew M Bradham |
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Institution: | Department of Biology, Georgia Southern University, PO Box 8042, Statesboro, GA 30460, USA |
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Abstract: | Preference for 14N over 15N was assessed for Myriophyllum spicatum L. by exposing shoots to the same initial concentration of N, but different isotopic compositions (100% 14N, 50% 14N and 50% 15N, and 100% 15N) for 6 weeks. Regardless of treatment, all available inorganic N was taken up by M. spicatum at similar rates. Significant differences in tissue isotopic composition were evident across treatments in 2 weeks, and persisted for the remainder of the experiment. At 6 weeks, atom (at) % 15N was twice as high in the 100% 15N treatment as in the 50% 15N treatment, and the at% of the 14N treatment (0% 15N) remained unchanged. This observed absence of preference for 14N in M. spicatum suggests that this species can be useful in determining N sources to freshwater systems, which often differ in 15N/14N ratio. |
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Keywords: | Freshwater Macrophyte Myriophyllum spicatum Stable nitrogen isotopes Uptake |
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