δ15N examination of the Lindeman-Hutchinson-Peters theory of increasin omnivory with trophic height in aquatic foodwebs

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.