Fish and riparian ecotones - a hypothesis

Authors present the hypothesis that freshwater fish diversity, recruitment and production depend greatly on riparian ecotones. These boundary environments are usually the most diverse elements of aquatic systems. Riparian ecotones moderate the transfer of energy and materials from the land, provide a high load of organic matter including invertebrate food, and moderate competition and predation among animals living in them. Riparian ecotones provide feeding places and shelter for fish, and are particularly important for their reproduction and earliest life-history stages. The complexity and biological importance of riparian ecotones depend on the extent to which the system is self-regulating, which depends in turn on geology, physiography, climate, vegetation, human activity and the age of the system. By changing riparian ecotone character, fish density can be regulated through controlling reproduction and recruitment, and energy flow through the food chain can be controlled for management of water quality.