Oecologia

, Volume 155, Issue 1, pp 21–31

Regulation of phosphorus stoichiometry and growth rate of consumers: theoretical and experimental analyses with Daphnia

Physiological Ecology - Original Paper

DOI: 10.1007/s00442-007-0896-7

Cite this article as:
Shimizu, Y. & Urabe, J. Oecologia (2008) 155: 21. doi:10.1007/s00442-007-0896-7

Abstract

Initial theories of ecological stoichiometry were based on the assumption that the mass-specific content of key nutrient elements (such as P), changes little within a consumer species. However, evidence has shown that this content changes substantially according to feeding conditions. To clarify how the specific P content (SP) of a consumer species depends on food conditions and relates to the growth rate, we constructed a multiple mass-balance model incorporating feeding and metabolic costs and stoichiometrically regulated releases for C and P. The validity of the model was then tested experimentally by examining the growth rates and SP of Daphnia pulicaria under various food conditions. The experimental observation agreed qualitatively well with the model, showing that the SP of consumers relates positively to growth rate at high food C:P ratios but negatively at low food C:P ratios. Thus, within a consumer species, individuals with high SP do not necessarily grow at high rates. The concordance in results between the model and our observation suggests that maintenance costs for both P and C are substantial regardless of food conditions and play crucial roles in determining the relationship between the SP and growth rate of consumers.

Keywords

Assimilation efficiencyCarbon:phosphorus ratioGrowth rate hypothesisMaintenance costsMass balance model

Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  1. 1.Division of Ecology and Evolutionary Biology, School of Life SciencesTohoku UniversitySendaiJapan