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Metabolic stoichiometry and the fate of excess carbon and nutrients in consumers

Metabolic stoichiometry and the fate of excess carbon and nutrients in consumers
Metabolic stoichiometry and the fate of excess carbon and nutrients in consumers
Animals encountering nutritionally imbalanced foods should release elements in excess of requirements in order to maintain overall homeostasis. Quantifying these excesses and predicting their fate is, however, problematic. A new model of the stoichiometry of consumers is formulated that incorporates the separate terms in the metabolic budget, namely, assimilation of ingested substrates and associated costs, protein turnover, other basal costs, such as osmoregulation, and the use of remaining substrates for production. The model indicates that release of excess C and nonlimiting nutrients may often be a significant fraction of the total metabolic budget of animals consuming the nutrient-deficient forages that are common in terrestrial and aquatic systems. The cost of maintenance, in terms of not just C but also N and P, is considerable, such that food quality is important even when intake is low. Many generalist consumers experience short-term and unpredictable fluctuations in their diets. Comparison of model output with data for one such consumer, Daphnia, indicates that mechanisms operating postabsorption in the gut are likely the primary means of regulating excess C, N, and P in these organisms, notably respiration decoupled from biochemical or mechanical work and excretion of carbon and nutrients. This stoichiometrically regulated release may often be in organic rather than inorganic form, with important consequences for the balance of autotrophic and heterotrophic processes in ecosystems.
ecological stoichiometry, metabolism, nutrient cycling, food quality, nutrition
0003-0147
1-11
Anderson, Thomas R.
dfed062f-e747-48d3-b59e-2f5e57a8571d
Hessen, Dag O.
b6d0c129-f3d6-4256-84dd-4614d4a5869b
Elser, James J.
31068a1f-b664-46bc-8f30-46adefea520c
Urabe, Jotaro
9b737b7a-a9d6-4ce8-ab30-d0b192f5dc4c
Anderson, Thomas R.
dfed062f-e747-48d3-b59e-2f5e57a8571d
Hessen, Dag O.
b6d0c129-f3d6-4256-84dd-4614d4a5869b
Elser, James J.
31068a1f-b664-46bc-8f30-46adefea520c
Urabe, Jotaro
9b737b7a-a9d6-4ce8-ab30-d0b192f5dc4c

Anderson, Thomas R., Hessen, Dag O., Elser, James J. and Urabe, Jotaro (2005) Metabolic stoichiometry and the fate of excess carbon and nutrients in consumers. The American Naturalist, 165 (1), 1-11. (doi:10.1086/426598).

Record type: Article

Abstract

Animals encountering nutritionally imbalanced foods should release elements in excess of requirements in order to maintain overall homeostasis. Quantifying these excesses and predicting their fate is, however, problematic. A new model of the stoichiometry of consumers is formulated that incorporates the separate terms in the metabolic budget, namely, assimilation of ingested substrates and associated costs, protein turnover, other basal costs, such as osmoregulation, and the use of remaining substrates for production. The model indicates that release of excess C and nonlimiting nutrients may often be a significant fraction of the total metabolic budget of animals consuming the nutrient-deficient forages that are common in terrestrial and aquatic systems. The cost of maintenance, in terms of not just C but also N and P, is considerable, such that food quality is important even when intake is low. Many generalist consumers experience short-term and unpredictable fluctuations in their diets. Comparison of model output with data for one such consumer, Daphnia, indicates that mechanisms operating postabsorption in the gut are likely the primary means of regulating excess C, N, and P in these organisms, notably respiration decoupled from biochemical or mechanical work and excretion of carbon and nutrients. This stoichiometrically regulated release may often be in organic rather than inorganic form, with important consequences for the balance of autotrophic and heterotrophic processes in ecosystems.

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Published date: 2005
Keywords: ecological stoichiometry, metabolism, nutrient cycling, food quality, nutrition
Organisations: National Oceanography Centre,Southampton

Identifiers

Local EPrints ID: 15672
URI: https://eprints.soton.ac.uk/id/eprint/15672
ISSN: 0003-0147
PURE UUID: 32b10714-6036-49ec-8fde-114d0d3184a5

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Date deposited: 13 May 2005
Last modified: 17 Jul 2017 16:48

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Contributors

Author: Thomas R. Anderson
Author: Dag O. Hessen
Author: James J. Elser
Author: Jotaro Urabe

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