DynaCom (Sp 6)
Biogeography studies the emergence and maintenance of biodiversity patterns in space and time depending not only on environmental abiotic factors such as physical and chemical environmental conditions but also on biotic factors like e.g. the interaction between species in competition or predator-prey relationships (MacArthur & Wilson 1967, Anderson et al. 2006). Apart from feeding types, dispersal abilities of organisms are important traits relevant to the formation of biodiversity patterns (Leibold et al. 2004, Legendre & Gauthier 2014, Heino et al. 2015). This dispersal of organisms can be characterized as active or passive. In aquatic environments, for example, active dispersal constitutes all swimming abilities of organisms, while passive dispersal is realized by hydrodynamic flows. The latter requires a coupling between biological and physical models (Werner et al. 2007). In plant communities, at the border-line between terrestrial and marine ecosystems passive dispersal corresponds to transport and distribution of seeds by the wind or by hydrodynamic flows e.g. in the pioneer zone of tidal flats.
We aim to study the impact of hydrodynamic flow structures, like e.g. vortices and jets,on the passive dispersal of species of different size and thus on biodiversity patterns in space. Based on different hydrodynamic models, we will investigate the role of such structures on a local (~1km), regional (10-100km) and global scale. Employing individual-based modelling of different organisms distinguished by their size, growth and mortality traits indicated by survival times, the impact of hydrodynamical flow patterns on community structure will be analyzed. According to their size, the transported organisms and seeds passively move either as tracers with the fluid or as inertial particles possessing different dispersal properties. In order to identify possible mechanisms of separation of different communities under the influence of mesoscale hydrodynamic structures as well as stochastic perturbations of environmental conditions, a kinematic velocity field will be developed. Those kinematic flows can be set up either to mimic the geometry of the experimental site in the back-barrier flat of Spiekeroog used by other sub-projects or to answer rather general questions about the relationship of colonization and extinction depending on the geographical distribution of islands on the one hand and the properties of the hydrodynamic flow on the other hand. The results of this study can be directly used to parameterize colonization-extinction models.