A rocky shore is an intertidal area of seacoasts where solid rock predominates. Rocky shores are biologically rich environments, and are a useful "natural laboratory" for studying intertidal ecology and other biological processes. Due to their high accessibility, they have been well studied for a long time and their species are well known.

Marine life

Many factors favour the survival of life on rocky shores. Temperate coastal waters are mixed by waves and convection, maintaining adequate availability of nutrients. Also, the sea brings

plankton Plankton are the diverse collection of organisms that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are ca ...

and broken organic matter in with each tide. The high availability of light (due to low depths) and nutrient levels means that

primary productivity Primary or primaries may refer to: Arts, entertainment, and media Music Groups and labels * Primary (band), from Australia * Primary (musician), hip hop musician and record producer from South Korea * Primary Music, Israeli record label Works * ...

of seaweeds and

algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...

can be very high. Human actions can also benefit rocky shores due to nutrient runoff. Despite these favourable factors, there are also a number of challenges to marine organisms associated with the rocky shore

ecosystem An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...

. Generally, the distribution of benthic species is limited by

salinity Salinity () is the saltiness or amount of salt (chemistry), salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensio ...

, wave exposure, temperature, desiccation and general stress. The constant threat of desiccation during exposure at low tide can result in dehydration. Hence, many species have developed adaptations to prevent this drying out, such as the 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 challenges such as temperature fluctuations due to tidal flow (resulting in exposure), changes in salinity and various ranges of illumination. Other threats include predation from birds and other marine organisms, as well as the effects of

pollution Pollution is the introduction of contaminants into the natural environment that cause harm. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the component ...

Ballantine scale

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 University of London Queen Mary University of London (QMUL, or informally QM, and formerly Queen Mary and Westfield College) is a public university, public research university in Mile End, East London, England. It is a member institution of the federal University ...

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, U.K., 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.

Zonation

Tidal movements of water creates zonation patterns along rocky shores from high to low-tide. The area above the high-tide mark is the supralittoral zone which is virtually a terrestrial environment. The area around the high-tide mark is known as the intertidal fringe. Between the high and low-tide marks is the intertidal or littoral zone. Below the low-tide mark is the sublittoral or subtidal zone. The presence and abundance of different animals and algae vary in different zones along the rocky shore due to differing adaptations to the varying levels of exposure to sun and desiccation along the rocky shore.

Pollution

Rocky shores are exposed to many forms of pollution, in particular pollution related to

oil spill An oil spill is the release of a liquid petroleum hydrocarbon into the environment, especially the marine ecosystem, due to human activity, and is a form of pollution. The term is usually given to marine oil spills, where oil is released into th ...

s. Prominent spills are the ''Torrey Canyon'' spill,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. the ''Amoco Cadiz'' spill outside the Brittany coast in FranceSeip, KL. 1984. The Amoco Cadiz Oil spill- at a glance. Mar. Poll. Bull. 15 (6) 218-220 and the ''Exxon Valdez'' spill in Prince William Sound, Alaska, US. Garbage such as plastics and metals being left behind by people is also a problem among many rocky coastlines that attract tourists.

Marine life

Ballantine scale

Zonation

Pollution

See also

References

Further reading