An individual-based model to evaluate the potential contribution of benthic resources to growth and production of a vertically migrating omnivorous macroinvertebrate

Omnivores that move across habitats likely provide systems with resistance to changing conditions. In lakes, Mysis may buffer these changes by accessing resources from both green (pelagic) and brown (benthic) energy pathways through diel vertical migration (DVM). However, Mysis exhibit partial DVM (pDVM), complicating the assessment of each pathway’s contributions. We developed an individual-based model (IBM) to explore how migration behavior, under seasonally varying pelagic resources, influences the relative contribution of benthic- and pelagic-based resources to Mysis growth and reproduction, assuming migration is driven solely by daily light cycles. Model growth and reproductive output were generally maximized and lifespan minimized with increasing pelagic resource profitability, consistent with field observations. However, some individuals grew larger and produced more offspring when pDVM slowed their growth but increased their lifespan, suggesting scope for different life history strategies to emerge from the model. Our IBM provides a foundation to integrate additional factors, such as size-dependent processes, to explore the mechanisms driving pDVM and how Mysis may respond to altered lake systems.