Reduction of wave forces within bare patches in mussel beds

Abstract

Wave forces on rocky shores can be an important agent structuring the ecology of inter-tidal communities. Proximity to nearby structures, such as those formed by mussel beds, may buffer organisms from the full danger of wave forces. This experiment measured the reduction of wave forces experienced by an object due to a surrounding artificial mussel bed. By being situated within a small (5 cm in radius) bare patch in this bed, a test object 1 cm in diameter experienced 30 to 62% reduction in wave forces compared to an unsheltered object. The effect drops off as bare patch size increases and is not noticeable in patches with radii of 15 cm or larger. This level of force reduction is relevant for a number of species living on rocky shores since measured, unmitigated wave forces exceed published tenacity values of many organisms. Thus, providing protection from wave forces offers a physical mechanism by which mussel beds help structure intertidal communities. © Inter-Research 2008.