DRIVERS OF CALANUS FINMARCHICUS: THE TOP, THE BOTTOM, AND THE QUEST FOR A HOLISTIC APPROACH

Abstract Ecosystems dynamics are an integrated response of the ecosystem's biological components to drivers. A long, unsolved ecological question is whether top-down trophic drivers (i.e. predation) or bottom-up drivers (often intended as climate, hydrography, food) control populations and ecosystems. Current methods for analysing drivers of ecosystems can have varying degrees of bias, giving rise to conflicting views in published research. In this study, we use an unbiased approach based on Genetic Programming for selecting drivers of a key species, Calanus finmarchicus, in the North Sea. This species has been widely discussed due to its importance for the food chain and its link to an ecosystem-wide regime shift in the late 1980's. The results suggest that both bottom-up and top-down drivers are involved in driving this species abundance.