title: Threshold elemental ratios of carbon and phosphorus in aquatic consumers.
abstract: Inadequate supply of one or more mineral elements can slow the growth of animal consumers and alter their physiology, life history and behaviour. A key concept for understanding nutrient deficiency in animals is the threshold elemental ratio (TER), at which growth limitation switches from one element to another. We used a stoichiometric model that coupled animal bioenergetics and body elemental composition to estimate TER of carbon and phosphorus (TER(C:P)) for 41 aquatic consumer taxa. We found a wide range in TER(C:P) (77-3086, ratio by atoms), which was generated by interspecific differences in body C : P ratios and gross growth efficiencies of C. TER(C:P) also varied among aquatic invertebrates having different feeding strategies, such that detritivores had significantly higher threshold ratios than grazers and predators. The higher TER(C:P) in detritivores resulted not only from lower gross growth efficiencies of carbon but also reflected lower body P content in these consumers. Supporting previous stoichiometric theory, we found TER(C:P) to be negatively correlated with the maximum growth rate of invertebrate consumers. By coupling bioenergetics and stoichiometry, this analysis revealed strong linkages among the physiology, ecology and evolution of nutritional demands for animal growth.
authors.forename: Paul C
authors.initials: PC
authors.lastname: Frost
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Benstead
authors.forename: Wyatt F
authors.initials: WF
authors.lastname: Cross
authors.forename: Helmut
authors.initials: H
authors.lastname: Hillebrand
authors.forename: James H
authors.initials: JH
authors.lastname: Larson
authors.forename: Marguerite A
authors.initials: MA
authors.lastname: Xenopoulos
authors.forename: Takehito
authors.initials: T
authors.lastname: Yoshida
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002244:Carbon / Q000378:metabolism*; D002965:Classification; D004032:Diet; D004463:Ecology; D017753:Ecosystem; D004734:Energy Metabolism; D020387:Food Chain; D007448:Invertebrates / Q000737:chemistry* / Q000502:physiology*; D009752:Nutritional Status; D010758:Phosphorus / Q000378:metabolism*; D014867:Water
chemical_list: D014867:Water; D010758:Phosphorus; D002244:Carbon