Much of the community structure seen on rocky shores reveals the strong direct or indirect influence of physical factors. Clear vertical zonation patterns exist along the emersion gradient particularly on sheltered shores. The dominant mid-shore species in the UK change gradually from fucoids on sheltered shores to barnacles or mussels on exposed shores. However, rocky shores are also characterised by intense biological interactions including competition for space and grazing and predation which create free space. These interactions do much to shape the community from setting the limits of the vertical distributions of many species to affecting the persistence of species assemblages. It must be emphasised, however, that the direction and intensity of biological interactions is strongly influenced by the underlying physical gradient as well as offshore factors which, for example, have a strong effect via recruitment regime. The type and importance of biological interactions will also change on a biogeographical scale due to the over-riding influence of climate.

Many of the dominant species on rocky shores facilitate the presence of other species by providing space and shelter. At the same time, these dominant species often exclude their competitors. The rocky shore community is therefore structured by a complex array of positive and negative interactions between species. Some of the better understood consequences of these interactions are discussed as are the interactions between the rocky shore and other marine and terrestrial ecosystems.

Zonation

Dynamics of populations and communities

Macroalgal influences

Larval supply

Energentics and interactions with other ecosystems

Key species

Biodiversity

References