Integrated field- & agent-based modelling: understanding the dynamics of the common barbel in the Meuse river

Abstract

Simulation models explicitly represent the underlying processes of systems. A standardised modelling framework that incorporates natural behaviour can improve accessibility for domain experts by being semantically intuitive. This thesis explores space conceptualisation in such frameworks to represent spawning habitat availability for swimming barbels. Space is often conceptualised using field-based approaches, where attributes have values throughout the space-time domain, and agent-based approaches, where entities are spatially bound and mobile. Integrating these paradigms allows population-level properties to emerge from individual responses to the environment. The software framework Campo integrates fields and agents (de Bakker et al.,2017). In the Common Meuse, the common barbel experiences a hydropeaking flow regime, leading to fluctuating habitat suitability and connectivity. This thesis examines barbel movement and spawning success in response to environmental changes, aiming to extend Campo's functionality to better represent and understand the barbel's habitat amidst hydropeaking conditions. The objective is to determine how flow regime and barbel behaviour affect spawning success and the optimal representation of these phenomena in Campo. Various movement modes were modelled, and the framework's ability to represent agents' sensing of the field was enhanced. These several operations have increased the accessibility and representation capabilities of ecosystems in Campo. Overall, heavily fluctuating as well as low discharges were detrimental to the barbel's spawning success. Nonetheless, agent integration does require generalisation of behaviour. Different movement behaviours resulted in significantly varied outcomes, with 50% of population reaching spawning sites between 1 and 33 days. This indicates a need for a more thorough understanding of barbel behaviour and highlighting the importance of integrating the agent-based perspective when assessing habitat suitability.