A rocky shore is an intertidal area of seacoasts where solid rock predominates. Rocky shores are biologically rich environments, and make the ideal natural laboratory for studying intertidal ecology and other biological processes. Because they are so accessible, they have been studied for a long time and their species are well known.
There are a large number of factors that favor the survival of life on rocky shores. Temperate coastal waters are mixed by waves and convection maintaining adequate availability of nutrients. Also, with the effect of the tides, the sea brings plankton and broken organic matter in with each tide. The high availability of light and nutrient levels means that primary productivity of seaweeds and algae can be very high. Human actions can benefit rocky shores with nutrient runoff.
Regardless of the factors that favour life on rocky shores, there are a number of challenges that marine organisms which use them as their habitat must face. Generally, the distribution of its benthic species is limited by salinity, wave exposure, temperature, desiccation and general stress. The constant threat of desiccation during exposure at low tide can result in dehydration which many creatures have developed strong adaptations to prevent such as production of mucous layers and shells. Many species use shells and holdfasts to provide stability against strong wave actions. There are also a variety of other issues such as varying temperature fluctuations due tidal flow, changes in salinity and various ranges of illumination which can make life very difficult for rocky shore organisms. This can be coupled with predation from birds and from other marine creatures and also the vast effects of pollution.
The Ballantine Scale is a biologically defined scale for measuring the degree of exposure level of wave action on a rocky shore. Devised in 1961 by W. J. Ballantine, then at the zoology department of Queen Mary College, London, the scale is based on the observation that where shoreline species are concerned "Different species growing on rocky shores require different degrees of protection from certain aspects of the physical environment, of which wave action is often the most important." The species present in the littoral zone therefore indicate the degree of the shore's exposure. The scale runs from (1) an "extremely exposed" shore, to (8) an "extremely sheltered" shore.
Rocky shores are exposed to many forms of pollution, in particular pollution related to oil spills. Prominent spills are the Torrey Canyon spill, The Amoco Cadiz spill outside the Brittany coast in France and the Exxon Valdez spill in Prince William Sound, Alaska, USA. Garbage such as plastics and metals being left behind by people is also a problem among many rocky coastlines that attract tourists.
- J H Connell, Community Interactions on Marine Rocky Intertidal Shores. 1972. Annual Review of Ecology and Systematic Vol. 3: 169-192
- J. R. Lewis (1964). The Ecology of Rocky Shores. English Universities Press, London.
- Ballantine (1961) page 1.
- Southward, AJ and Southward, EC. 1978. Recolonization of Rocky shores after the use of toxic dispersants to clean up the Torrey Canyon spill. J. Fish. Res. Board. Can 35:682-706.
- Seip,KL. 1984. The Amoco Cadiz Oil spill- at a glance. Mar. Poll. Bull. 15 (6) 218-220
- Cruz-Motta J. J., Miloslavich P., Palomo G., Iken K., Konar B., et al. (2010). "Patterns of Spatial Variation of Assemblages Associated with Intertidal Rocky Shores: A Global Perspective". PLoS ONE 5(12): e14354. doi:10.1371/journal.pone.0014354.