Regulation of species richness by advection and richness-dependent processes in a coastal fish community

Abstract

In coastal fish communities, both top-down and bottom-up processes influence the dynamics of individual species. Here, we demonstrate how advective processes in the coastal zone of the Skagerrak basin affect the main predator, the cod (Gadus morhua), as a bottom-up process, while gobies are influenced by top-down processes such as predation and competition. A model for the regulation of fish community dynamics, incorporating both bottom-up processes, corresponding to disturbance, and top-down processes are outlined. Wind stress may be seen as a proxy variable for wind-driven currents that results in dispersal of eggs and larvae and advection of prey species into coastal areas. About half of the fjords along the southern Norwegian Skagerrak coast are well fitted when wind stress is included as an environmental forcing factor in the period 1957–94. Along with richness-dependent regulation, the dynamics of fish-species richness are well predicted with the simple model presented.