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Title (Primary) Consumer-resource stoichiometry as a predictor of trophic discrimination (Δ13C, Δ15N) in aquatic invertebrates
Author Brauns, M.; Boëchat, I.G.; de Carvalho, A.P.C.; Graeber, D.; Gücker, B.; Mehner, T.; von Schiller, D.;
Journal Freshwater Biology
Year 2018
Department ASAM; FLOEK;
Volume 63
Issue 10
Language englisch;
POF III (all) T32;
Supplements https://onlinelibrary.wiley.com/doi/abs/10.1111/fwb.13129
Keywords consumer-resource elemental imbalance; ecological stoichiometry; lipids; macroinvertebrates; stable isotopes
Abstract
  1. Trophic interactions are important pathways of energy and matter fluxes in food webs and are commonly quantified using stable isotopes of carbon (δ13C) and nitrogen (δ15N). An important prerequisite for this approach is knowledge on the isotopic difference between consumer and resource (trophic discrimination, Δ13C and Δ15N). The range and mechanism causing variation of trophic discrimination factors remain unclear.
  2. We conducted a controlled feeding experiment with 13 freshwater benthic invertebrate taxa fed with six resources to test if the C:N, C:P and N:P ratios of consumer, resources and consumerresource imbalances are significant predictors of Δ13C and Δ15N. We compiled the available literature on discrimination factors for aquatic invertebrates from controlled feeding experiments and field studies to compare the variation in trophic discrimination.
  3. Molar C:N and C:P ratios of resources as well as consumerresource imbalances of C:N were significantly related to Δ13C and explained more than 40% of variation of Δ13C, respectively. Resource %N was unrelated to Δ15N, but consumer N:P explained 20% of variation of Δ15N.
  4. Our data taken together with the literature compilation provide a mean Δ13C of 0.1‰ (SD = 2.2, N = 157) and a mean Δ15N of 2.6‰ (SD = 2.0, N = 155) for aquatic invertebrates to be used in mixing model analysis for estimating dietary proportions.
  5. Our study bridges the currently separated disciplines of stable isotope discrimination and ecological stoichiometry and shows that resource C:N:P and consumerresource imbalances are powerful predictors of invertebrate trophic discrimination. Including these stoichiometric predictors into stable isotope mixing models may improve the estimates of the contribution of organic matter sources to the diet of invertebrate consumers. The overall discrimination factors for aquatic invertebrates derived from this study may help to produce precise estimates in trophic ecology if taxonspecific discrimination factors are unavailable.
ID 20613
Persistent UFZ Identifier http://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=20613
Brauns, M., Boëchat, I.G., de Carvalho, A.P.C., Graeber, D., Gücker, B., Mehner, T., von Schiller, D. (2018):
Consumer-resource stoichiometry as a predictor of trophic discrimination (Δ13C, Δ15N) in aquatic invertebrates
Freshw. Biol. 63 (10), 1240 - 1249