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Rescaling the trophic structure of marine food webs
Author(s) -
Hussey Nigel E.,
MacNeil M. Aaron,
McMeans Bailey C.,
Olin Jill A.,
Dudley Sheldon F.J.,
Cliff Geremy,
Wintner Sabine P.,
Fennessy Sean T.,
Fisk Aaron T.
Publication year - 2014
Publication title -
ecology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.852
H-Index - 265
eISSN - 1461-0248
pISSN - 1461-023X
DOI - 10.1111/ele.12226
Subject(s) - trophic level , food web , apex predator , ecosystem , isotope analysis , ecology , predation , marine ecosystem , food chain , stable isotope ratio , δ15n , environmental science , biology , δ13c , physics , quantum mechanics
Measures of trophic position ( TP ) are critical for understanding food web interactions and human‐mediated ecosystem disturbance. Nitrogen stable isotopes (δ 15 N) provide a powerful tool to estimate TP but are limited by a pragmatic assumption that isotope discrimination is constant (change in δ 15 N between predator and prey, Δ 15 N = 3.4‰), resulting in an additive framework that omits known Δ 15 N variation. Through meta‐analysis, we determine narrowing discrimination from an empirical linear relationship between experimental Δ 15 N and δ 15 N values of prey consumed. The resulting scaled Δ 15 N framework estimated reliable TP s of zooplanktivores to tertiary piscivores congruent with known feeding relationships that radically alters the conventional structure of marine food webs. Apex predator TP estimates were markedly higher than currently assumed by whole‐ecosystem models, indicating perceived food webs have been truncated and species‐interactions over simplified. The scaled Δ 15 N framework will greatly improve the accuracy of trophic estimates widely used in ecosystem‐based management.