The invariance of production per unit of food cons

Authors: R Wiff M A Barrientos A M Segura A C Milessi

Publish Date: 2017/02/03

Volume: 136, Issue: 3-4, Pages: 179-185

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Abstract

The amount of biomass production per unit of food consumed P/Q represents an important quantity in ecosystem functioning because it indicates how efficient a population transforms ingested food into biomass Several investigations have noticed that P/Q remains relatively constant or invariant across fish population that feed at the same foodtype level carnivorous/herbivorous Nevertheless theoretical explanation for this invariant is still lacking In this paper we demonstrate that P/Q remains invariant across fish populations with stableage distribution Three key assumptions underpin the P/Q invariant 1 the ratio between natural mortality M and von Bertalanffy growth parameter k M/k ratio should remain invariant across fish populations 2 a parameter defining the fraction of ingested food available for growth needs to remain constant across fish that feed at the same trophic level 3 third the ratio between length at age 0 l 0 and asymptotic length l infty should be constant across fish populations The influence of these assumptions on the P/Q estimates were numerically assessed considering fish populations of different lifespan Numerical evaluations show that the most critical condition highly relates to the first assumption M/k Results are discussed in the context of the reliability of the required assumption to consider the P/Q invariant in stableage distributed fish populationsWe are grateful to the anonymous reviewers for their valuable comments and suggestions R Wiff was supported by CONICYT Chile scholarship for postgraduate studies abroad “Beca Presidente de la Republica para Estudios de Postgrado en el Extranjero” by CONICYT/FONDECYT post doctoral Project Number 3130425 and by CAPES project FONDECYT Number FB 0002 2014 AM Segura thanks ANII for the Grant FCE 3 2013 1 100394

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