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Stoichiometric imbalances between detritus and detritivores are related to shifts in ecosystem functioning

Frainer, André and Jabiol, Jérémy and Gessner, Mark O. and Bruder, Andreas and Chauvet, Eric and McKie, Brendan G. Stoichiometric imbalances between detritus and detritivores are related to shifts in ecosystem functioning. (2016) Oikos, 125 (6). 861-871. ISSN 0030-1299

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Official URL: http://dx.doi.org/10.1111/oik.02687

Abstract

How are resource consumption and growth rates of litter-consuming detritivores affected by imbalances between consumer and litter C:N:P ratios? To address this question, we offered leaf litter as food to three aquatic detritivore species, which represent a gradient of increasing body N:P ratios: a crustacean, a caddisfly and a stonefly. The detritivores were placed in microcosms and submerged in a natural stream. Four contrasting leaf species were offered, both singly and in two-species mixtures, to obtain different levels of stoichiometric imbalance between the resources and their consumers. The results suggest that detritivore growth was constrained by N rather than C or P, even though 1) the N:P ratios of the consum- ers’ body tissue was relatively low and 2) microbial leaf conditioning during the experiment reduced the N:P imbalance between detritivores and leaf litter. This surprisingly consistent N limitation may be a consequence of cumulative N-demand arising from the production of N-rich chitin in the exoskeletons of all three consumer species, which is lost during regular moults, in addition to N-demand for silk production by the caddisfly. These N requirements are not commonly quantified in stoichiometric analyses of arthropod consumers. There was no evidence for compensatory feeding, but when offered mixed- species litter varying in C:N:P ratios, detritivores consumed more of the litter species showing the highest N:P and lowest C:N ratio, accelerating the mass loss of the preferred leaf species in the litter mixture. These results show that imbalances in consumer–resource stoichiometry can have contrasting effects on coupled processes, highlighting a challenge in developing a mechanistic understanding of the role of stoichiometry in regulating ecosystem processes such as leaf litter decomposition.

Item Type:Article
Additional Information:Thanks to Nordic Ecological Society editor. The definitive version is available at http://onlinelibrary.wiley.com/ The original PDF of the article can be found at Oikos website : http://onlinelibrary.wiley.com/doi/10.1111/oik.2016
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Other partners > Leibniz-Institut für Gewässerökologie und Binnenfischerei - IGB (GERMANY)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
Other partners > Technische Universität Berlin - TU Berlin (GERMANY)
Other partners > Umea University (SWEDEN)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UPS (FRANCE)
Other partners > Swiss Federal Institute of Aquatic Science and Technology - EAWAG (SWITZERLAND)
Other partners > Sveriges lantbruksuniversitet - SLU (SWEDEN)
Other partners > Eidgenössische Technische Hochschule Zürich - ETHZ (SWITZERLAND)
Other partners > Universitetet i Tromsø – Norges arktiske universitet - UiT (NORWAY)
Other partners > University of Otago (NEW ZEALAND)
Laboratory name:
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Deposited By: Eric Chauvet
Deposited On:31 Aug 2016 09:26

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