An agent-based bioenergetics model for predicting impacts of environmental change on a top marine predator, the Weddell seal
Authored by Roxanne S Beltran, J Ward Testa, Jennifer M Burns
Date Published: 2017
DOI: 10.1016/j.ecolmodel.2017.02.002
Sponsors:
United States National Science Foundation (NSF)
Platforms:
R
Model Documentation:
ODD
Mathematical description
Model Code URLs:
Model code not found
Abstract
One of the crucial scientific challenges of this century is
characterizing the vulnerability of ecosystems to climate change.
Bioenergetics models can provide a theoretical construct for addressing
specific physiological and ecological hypotheses about how individuals
may respond; however, many models fail to link energy deficiencies with
reproductive consequences, and thus cannotbe used to predict
population-level impacts. Here, we present an agent-based,
ecophysiological model that simulates the energy balance of adult,
female Weddell seals (Leptonychotes weddellii). The input parameters
include physiological values and population -wide ranges for the
duration and phenology of life history events. Energy intake depends on
foraging effort and stochastic prey availability, whereas energy
expenditure is calculated from time and behavior-specific demands. The
simulated seal selects an activity (forage, nurse pup, molt, rest) based
on body condition and life history constraints. At the end of each
timestep, the energy budget is balanced, and catabolism or anabolism
occurs. Following model development and validation with empirical data,
simulations were run to study the responses of individuals to: (1)
baseline conditions; and (2) reduced prey availability. As expected, the
model replicated the known fluctuations in energetic requirements
associated with reproduction and molt. A 10\% reduction in prey
availability resulted in seals foraging more and resting less. At the
end of the year-long simulations, animals in the baseline simulation had
significantly higher body masses than animals in the perturbation
simulation. The model was successfully used to explore decision-based
energy allocation strategies that occur under different energetic
stressors and to elucidate how extrinsic conditions can impact
individual fitness. Identifying the temporal sensitivities of Weddell
seals to predicted anthropogenic changes is a valuable contribution to
the study of global change biology and can inform management decisions
in polar regions. (C) 2017 Elsevier B.V. All rights reserved.
Tags
Agent-based model
Climate change
Bioenergetics
Climate-change
Habitat
selection
Southern-ocean
Halichoerus-grypus
Pinnipeds
Fishing
pressure
Northern elephant seal
Trophic-level predators
Leptonychotes-weddellii
Harp seals
Phocid seals
Grey seal