ABSTRACT
Some sediments occur on most rocky coasts, to the point that some authors have recently recognised the artificiality of the traditional separation between rocky and sandy shores (Bally et al. 1984, Jørgensen & Gulliksen 2001). Sediments are added to rocky coasts by many natural and human-related processes (Fig. 1), and are redistributed as a function mainly of sediment characteristics, hydrodynamic conditions, bottom profile, and biological factors (Moore 1972, 1973a, Hiscock 1983). These factors operate over a range of scales. Thus, while sediment deposition can be relatively predictable at large spatial and temporal scales, depending on the source and magnitude of sediment loads, at small scales, relevant to individual organisms, patterns may be highly heterogeneous and unpredictable (Trowbridge 1996, Airoldi & Virgilio 1998). This section, does not attempt to give detailed information on these topics, but rather to provide some baseline information relevant to understanding the possible effects of sedimentation on rocky coast organisms, and to analyse problems related to the measurement and comparison of sedimentation rates across different habitats.
