δ15N examination of the Lindeman-Hutchinson-Peters theory of increasin omnivory with trophic height in aquatic foodwebs |
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Authors: | Robert L France |
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Institution: | (1) Harvard University Graduate School of Design, 48 Quincy Street, 02138 Cambridge, MA, USA |
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Abstract: | The advent of stable nitrogen isotope analysis in ecological research has at last enabled precise identification of trophic
position and omnivory due to the differential enrichment of15N over14N with progressive assimilation up the foodweb. I compiled literature data on δ15N values in freshwater and marine foodwebs to search for qeneral patterns in omnivory, specifically the supposition originally
proposed by Lindeman (1942) and most recently advanced by Peters (1977), that omnivory should increase with trophic height
or position. Omnivory, measured as average intraspecific variability in δ15N, was indeed found to increase with trophic height, such that species at the top of foodwebs were comprised of animals relying,
on average, on energy originating from a mixture of different trophic categories. |
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Keywords: | foodwebs omnivory δ 15N variability trophic position |
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