We added a vertical migration trait using the already existing swimming equation of the model (see appendix, equation XX). In the original model, the swimming speed (or actually flux) was based on an allometric relationship. We used the body length of the functional species (here their equivalent spherical diameter - ESD) divided by a factor of six to estimate their swimming speed. Then we included a tangential hyperbolic function to the swimming formula in order to have a more realistic swimming behavior (Zakardjian et al. 1999). Each phase of the metazoan (active or dormant) were going to a specific depth, a shallow target depth of 25-meter for the active groups and a deep 500-meter target depth for the dormant groups. These depths were chosen following in situ observation of copepods population in the Amundsen Gulf (Darnis et al. 2012, Darnis et al. 2012).