BIOND LAB

Models of chemical and biological processes in the pelagic as well as in the benthic part of the Wadden Sea are very complex and highly nonlinear. As known for a long time nonlinearities can give rise to sudden changes in the behaviour of a system. Such changes are caused by instabilities which can occur if environmental parameters cross certain threshold values (bifurcations). From an ecological point of view such instabilities may endanger the ecosystem since the new state of the ecosystem after the bifurcation can be characterised by different properties, i. e. a different composition of the species community. Moreover, nonlinear systems can exhibit different states for a given set of parameters. This phenomenon is called multistability. If several different states coexist then it crucially depends on the initial conditions which of these states is finally realised.