Modelling southern elephant seals Mirounga leonina using an individual-based model coupled with a dynamic energy budget.

De-Hua Wang,Merel Goedegebuure,Stuart P Corney,Mark A Hindell,Jessica Melbourne-Thomas,Clive R Mcmahon

doi:10.1371/journal.pone.0194950

Abstract

Higher trophic-level species are an integral component of any marine ecosystem. Despite their importance, methods for representing these species in end-to-end ecosystem models often have limited representation of life histories, energetics and behaviour. We built an individual-based model coupled with a dynamic energy budget for female southern elephant seals Mirounga leonina to demonstrate a method for detailed representation of marine mammals. We aimed to develop a model which could i) simulate energy use and life histories, as well as breeding traits of southern elephant seals in an emergent manner, ii) project a stable population over time, and iii) have realistic population dynamics and structure based on emergent life history features (such as age at first breeding, lifespan, fecundity and (yearling) survival). We evaluated the model’s ability to represent a stable population over long time periods (>10 generations), including the sensitivity of the emergent properties to variations in key parameters. Analyses indicated that the model is sensitive to changes in resource availability and energy requirements for the transition from pup to juvenile, and juvenile to adult stage. This was particularly the case for breeding success and yearling survival. This model is suitable for use as a standalone tool for investigating the impacts of changes to behaviour and population responses of southern elephant seals.

Highlights

Models are important tools for understanding and predicting changes in ecosystem state, and informing management (e.g. [1, 2, 3])
This is important because for the first time we present information showing how environmental change is linked to individual animal performance; dynamic energy budget (DEB)-IBM for southern elephant seals how performance affects vital rates, and; how changes in vital rates are manifested at the population level
We focused on female southern elephant seals as they have been part of extensive longitudinal studies on Macquarie Island, and census data on their life history and breeding traits are readily available

Summary

Introduction

Models are important tools for understanding and predicting changes in ecosystem state, and informing management (e.g. [1, 2, 3]). Models are important tools for understanding and predicting changes in ecosystem state, and informing management The optimal level of detail with which to model specific ecosystem components depends on the aim of the model; detailed representations of ecosystem components can increase the cost associated with development and use of models, and intermediate levels of complexity can improve the predictive capacity of models [4]. Deciding on the necessary level of complexity required in a model is important; recent. Acecrc.org.au), the Institute for Marine and Antarctic Studies (www.imas.utas.edu.au/home), through the Australian Antarctic Science Program (AAS 4347), and through an Australian Government Research Training Program Scholarship. The Australian Antarctic Division (www.antarctica.gov.au) through the Australian National Antarctic Research Expeditions (ANARE) supported this research. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

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