Abstract
The objective of the present project is to develop existing modeling techniques to describe the dynamics of multispecies system by integrating stage-structured population dynamics with food web dynamics. Special attention will be paid to interactions among species and indirect effects of commercial fishing in the aquatic ecosystems of Lake Vänern and Vättern with the goal of understanding (i) the dynamics of vendace and smelt in Lake Vänern and (ii) causes for the decline of arctic char in Lake Vättern. Indirect effects among species in ecosystems are mediated by a series of direct effects between species and consist of positive and negative feedback loops. Disregarding indirect effects by assuming that community responses to perturbations can be understood and predicted by focusing on a few direct pairwise interactions can lead to very misleading results. This advocates for a food web oriented approach to study effects of human activity on ecosystems. Furthermore, stage-structure is an important, yet in most food web studies seldom appreciated characteristic of organisms. Thus, the purpose of the present project is to improve available tools to study the effects of disturbances (e.g. human activity) on ecosystems. Reaching these objectives has applied implications and will advance the potential of food web theory to (i) asses the likely consequences of perturbations on ecosystems and (ii) identify keystone species or interactions for the structure and function of ecosystems.
Sweden