Influence of Aquatic and Semi-Aquatic Organisms on Channel Forms and Processes
Recently, an interest has emerged in the role of aquatic biota as geomorphic agents. Although it is difficult to untangle the interconnectedness of the biotic and abiotic constituents within channel networks, a few theoretical efforts and several recent empirical studies have capitalized on this interconnectivity, providing research that narrows the gap between the once widely separated fields of stream ecology and fluvial geomorphology. This chapter provides a review of the existing literature by focusing on specific process- and form-based research involving biological organisms as geomorphic agents. Wherever possible, comparisons are drawn from the more well-understood and documented hydraulic-based research. We conclude that with the exception of beaver and large grazing animals, the reviewed literature suggests that aquatic and semi-aquatic species act as limited geomorphic agents. That is, their scope of influence on channel forms and processes is typically direct, seasonally variable, and usually only meaningful at reach-scales during base-flow conditions.
