Impacts of disturbances on marine populations – the importance of animal movements and energetics
Marine species live in complex landscapes with scattered food and numerous disturbances that interrupt the animals’ normal foraging behaviour. Cetaceans are disturbed by noise from ships, seismic surveys, offshore construction work, etc., but the extent to which this influences the individuals’ energy balance depends on the time it takes till they can commence feeding after being disturbed. Animals that are able to move to alternative foraging grounds, or to return to the area they were scared away from, are thus less severely affected. Ultimately, the energetic status of individuals can influence their survival, reproduction, and also the survival of the population, so to fully understand the population consequences of increasing levels of disturbance we need models that explicitly account for animal movement and energetics.
One type of models that can directly incorporate animal movement, energetics and responses to different types of disturbances, are agent-based models. In these models, population dynamics emerge from interactions among simulated animals. They are based directly on the same processes that govern the dynamics of populations in nature, which gives them higher predictive power than statistical models. But they are only suitable for species we know a lot about. In this presentation I discuss how agent-based models have improved our ability to predict population consequences of disturbances in recent years, what kinds of data that are required to parameterize them, and how they can be developed further for assessing the cumulative impacts of different kinds of disturbances.