Coupling of dietary phosphorus and growth across diverse fish taxa: a meta-analysis of experimental aquaculture studies
- Benstead, Jonathan P. [ Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama, USA ]
- Hood, James M. [ Montana State University: Ecology ]
- Whelan, Nathan V. [ Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama, USA ]
- Kendrick, Michael R. [ Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama, USA ]
- Nelson, Daniel [ Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama, USA ]
- Hanninen, Amanda F. [ Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama, USA ] [ Department of Biology, University of Virginia, Charlottesville, Virginia, USA ]
- Demi, Lee M. [ Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama, USA ]
Imbalances in phosphorus (P) intake relative to demand negatively affect animal growth, but their consequences are less understood for vertebrates, in which bone represents a significant and potentially flexible pool of P. Flexibility in body-P content could buffer vertebrates from the effects of imbalances between P intake and demand, reducing the likelihood of a sharp stoichiometric “knife-edge†in the relationship between growth rate and diet-P level. We conducted a meta-analysis of published aquaculture experiments that tested effects of diet %P on fish growth rate (49 studies, 28 species) and body-P content (27 of the studies in the main data set, 20 species). Our meta-analysis revealed significant P limitation of growth, as well as significant negative effects of excess P on growth rate. Diet-P thresholds for these effects occurred at ecologically relevant levels (optimal diet-P of 1.2% ± 0.45%, mean ± SD, under experimental conditions of high ration). Finally, the analysis also suggested a pattern of relatively shallow relationships between growth rate and diet-P level, coupled with surprisingly flexible body-P content in fishes. This result is consistent with fish using flexible body-P content (presumably mediated through bone P) to buffer imbalances between P intake and demand. Together, our results provide evidence for a relatively “dull†stoichiometric “knife-edge†in fishes, driven in part by flexible body-P content.