Water flow, sediment dynamics and benthic ecology

Publisher Summary

This chapter introduces some of the hydrodynamic and sedimentological concepts that are relevant to the study of benthic systems. The influence of water flow is an important factor shaping the ecology of aquatic systems. However, the integration of scientific studies required for the understanding of the influence of flow on benthic ecology is still relatively underdeveloped. The nature of the flow, whether laminar or turbulent, and how this influences the stress experienced by the bed is considered. The importance of the balance between viscous and inertial forces and the significance of the Reynolds number is described. Particular reference is made to skin friction, which initiates sediment erosion from relatively smooth beds. The complex erosional behaviour of cohesive sediments is described including the recent classification of sediment erosion in type I, type I1, and possible intermediate behaviors. Biofilm assemblages can form highly structured communities at the sediment surface, and evidence from the literature suggests that components of the biofilm can be detected in suspension before erosion of the sediment bed, emphasizing the biological nature of the bed surface. Future lines of research including the state-of-the-art in terms of modeling sediment dynamics, particularly with respect to biological properties, and the recent use of remote sensing techniques to classify habitat type and make inferences about sediment behaviour are considered.