4 research outputs found
A generalized Dynamic Energy Budget model including 3D shape changes for modeling small pelagic fish growth
International audienceSmall pelagic fish (SPF) are key components of marine ecosystems, transporting energy from the lower to the upper trophic levels and thereby influencing the dynamics of the entire ecosystem. Understanding their complex growth patterns from early life stages to adulthood is fundamental to accurately predict larval survival and predator-prey dynamics, which are influenced by individual size. However, growth models are generally unable to accurately reproduce the growth acceleration and deceleration phases observed, particularly during early life stages. Here we propose a growth model based on a Dynamic Energy Budget model (modified as in Maury, 2019 to properly account for size-dependence of maintenance) that captures deviations from pure isomorphy. It represents the fishâs body as an ellipsoid and differentially allocates volumetric growth to length, height and width as a function of the distance between the current shape and characteristic stage-dependent shape attractors (expressed as width/length and height/width ratios). The resulting surface-to-volume ratios mechanistically explain the âmetabolic accelerationâ often invoked to explain early life growth patterns. We estimated model parameters for three important SPF species in the Benguela upwelling system, using data covering growth at all life-stages, transitions between life-stages, and reproduction. The calibrated models reproduced the observed deviations from isomorphy, with exponential length-dominated growth until metamorphosis, then a shift to height- and width-dominated growth (with a corresponding deceleration of length growth) until the adult shape is reached, and finally isomorphic (characteristic von Bertalanffy) length growth. These deviations from the usual von Bertalanffy growth model could profoundly affect our understanding of larval survival, predator-prey and ecosystem-dynamic
A generalized Dynamic Energy Budget model including 3D shape changes for modeling small pelagic fish growth
Small pelagic fish (SPF) are key components of marine ecosystems, transporting energy from the lower to the upper trophic levels and thereby influencing the dynamics of the entire ecosystem. Understanding their complex growth patterns from early life stages to adulthood is fundamental to accurately predict larval survival and predator-prey dynamics, which are influenced by individual size. However, growth models are generally unable to accurately reproduce the growth acceleration and deceleration phases observed, particularly during early life stages. Here we propose a growth model based on a Dynamic Energy Budget model (modified as in Maury, 2019 to properly account for size-dependence of maintenance) that captures deviations from pure isomorphy. It represents the fishâs body as an ellipsoid and differentially allocates volumetric growth to length, height and width as a function of the distance between the current shape and characteristic stage-dependent shape attractors (expressed as width/length and height/width ratios). The resulting surface-to-volume ratios mechanistically explain the âmetabolic accelerationâ often invoked to explain early life growth patterns. We estimated model parameters for three important SPF species in the Benguela upwelling system, using data covering growth at all life-stages, transitions between life-stages, and reproduction. The calibrated models reproduced the observed deviations from isomorphy, with exponential length-dominated growth until metamorphosis, then a shift to height- and width-dominated growth (with a corresponding deceleration of length growth) until the adult shape is reached, and finally isomorphic (characteristic von Bertalanffy) length growth. These deviations from the usual von Bertalanffy growth model could profoundly affect our understanding of larval survival, predator-prey and ecosystem-dynamic
Caractérisation des différences de traits de vie chez les anchois du genre Engraulis spp.: Apports d'une approche de modélisation de type Dynamic Energy Budget
International audienceLes petits poissons pĂ©lagiques (PPP), au cĆur du rĂ©seau trophique, ont un rĂŽle clĂ© dans lâĂ©cosystĂšme. ReprĂ©sentant 20% des captures de pĂȘche et Ă©tant la principale source dâomĂ©ga-3 pour lâHomme, ils sont cruciaux pour la sĂ©curitĂ© alimentaire mondiale. Leur biomasse varie suivant les annĂ©es et entre espĂšces mais les facteurs explicatifs restent Ă dĂ©terminer. Des parties de leur cycle de vie sont difficiles Ă Ă©tudier particuliĂšrement lâinvestissement reproducteur. Le modĂšle bioĂ©nergĂ©tique basĂ© sur la thĂ©orie Dynamic Energy Budget (DEB) permet de dĂ©finir le cycle de vie de lâindividu en quantifiant lâimpact des conditions environnementales et de la physiologie sur trois processus physiologiques : croissance, dĂ©veloppement et reproduction. Comparer les traits de vie et les conditions climatiques des rĂ©gions avait pour but de quantifier les potentielles diffĂ©rences environnementales et physiologiques. LâĂ©tude sâest focalisĂ©e sur les 7 principales populations dâanchois du genre Engraulis spp. afin dâĂ©tablir la variabilitĂ© inter-populationnelle des traits de vie de ce groupe dâespĂšces. Les rĂ©sultats rĂ©vĂšlent que (1) des environnements contrastĂ©s reproduisent ces diffĂ©rences de traits de vie, (2) la dĂ©finition de la nourriture disponible pour un individu doit prendre en compte la compĂ©tition et la diffĂ©rence de qualitĂ© de nourriture et (3) un compromis entrecroissance et reproduction nâa pas pu ĂȘtre Ă©tabli. Notre Ă©tude a donc confirmĂ© lâhypothĂšse de travail dâune plasticitĂ© des traits de vie de lâanchois en fonction des conditions environnementales. Les perspectives de lâĂ©tude discutĂ©es concernent une meilleure prise en compte de la variabilitĂ© spatiale et interannuelle
Caractérisation des différences de traits de vie chez les anchois du genre Engraulis spp.: Apports d'une approche de modélisation de type Dynamic Energy Budget
International audienceLes petits poissons pĂ©lagiques (PPP), au cĆur du rĂ©seau trophique, ont un rĂŽle clĂ© dans lâĂ©cosystĂšme. ReprĂ©sentant 20% des captures de pĂȘche et Ă©tant la principale source dâomĂ©ga-3 pour lâHomme, ils sont cruciaux pour la sĂ©curitĂ© alimentaire mondiale. Leur biomasse varie suivant les annĂ©es et entre espĂšces mais les facteurs explicatifs restent Ă dĂ©terminer. Des parties de leur cycle de vie sont difficiles Ă Ă©tudier particuliĂšrement lâinvestissement reproducteur. Le modĂšle bioĂ©nergĂ©tique basĂ© sur la thĂ©orie Dynamic Energy Budget (DEB) permet de dĂ©finir le cycle de vie de lâindividu en quantifiant lâimpact des conditions environnementales et de la physiologie sur trois processus physiologiques : croissance, dĂ©veloppement et reproduction. Comparer les traits de vie et les conditions climatiques des rĂ©gions avait pour but de quantifier les potentielles diffĂ©rences environnementales et physiologiques. LâĂ©tude sâest focalisĂ©e sur les 7 principales populations dâanchois du genre Engraulis spp. afin dâĂ©tablir la variabilitĂ© inter-populationnelle des traits de vie de ce groupe dâespĂšces. Les rĂ©sultats rĂ©vĂšlent que (1) des environnements contrastĂ©s reproduisent ces diffĂ©rences de traits de vie, (2) la dĂ©finition de la nourriture disponible pour un individu doit prendre en compte la compĂ©tition et la diffĂ©rence de qualitĂ© de nourriture et (3) un compromis entrecroissance et reproduction nâa pas pu ĂȘtre Ă©tabli. Notre Ă©tude a donc confirmĂ© lâhypothĂšse de travail dâune plasticitĂ© des traits de vie de lâanchois en fonction des conditions environnementales. Les perspectives de lâĂ©tude discutĂ©es concernent une meilleure prise en compte de la variabilitĂ© spatiale et interannuelle