Wave actions are well known to influence the structure of biological communities on rocky shores: Sheltered shores tend to be dominated by large seaweeds, while wave-exposed headlands and islands are covered by small species forming turfs or crusts on the rock. A paper just published in Marine Ecology Progress Series discusses how these differences come about. A group of SAMS scientists led by Mike Burrows have produced a model to measure the principal cause of differences in wave action along the coast: wave fetch (= the distance to the nearest land offshore) combined with wind strength and direction. By relating these to communities observed around the Scottish coast the model explains how rocky shore communities change in relation to wave fetch.
This approach opens several new possibilities: The role of species interactions in structuring communities can be improved by comparing observed with predicted communities and relating the differences to numbers of predators and grazers. Effects of climate change (here in particular wind) on rocky shore communities can be predicted, as can the effects of changing waves from building offshore wind farms or wave-energy devices. Finally the coast-wide approach should help in mapping coastal resources.
Burrows MT, Harvey R and Robb L (2008) Wave exposure indices from digital coastlines and the prediction of rocky shore community structure. Marine Ecology Progress Series 353: 1-12 [doi: 10.3354/meps07284]