User:Lglayman/Intertidal zone

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The intertidal zone, also known as the foreshore or seashore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species of life, such as seastars, sea urchins, and many species of coral with regional differences in biodiversity. Sometimes it is referred to as the littoral zone, although that can be defined as a wider region.

The well-known area also includes steep rocky cliffs, sandy beaches, bogs or wetlands (e.g., vast mudflats). The area can be a narrow strip, as in Pacific islands that have only a narrow tidal range, or can include many meters of shoreline where shallow beach slopes interact with high tidal excursion. The peritidal zone is similar but somewhat wider, extending from above the highest tide level to below the lowest. Organisms in the intertidal zone are adapted to an environment of harsh extremes, living in water pressure with the potential of reaching 5,580 pounds per square inch. The intertidal zone is also home to several species from different phyla (Porifera, Annelida, Coelenterata, Mollusca, Arthropoda, etc.).

Water is available regularly with the tides that can vary from brackish waters, fresh with rain, to highly saline and dry salt, with drying between tidal inundations. Wave splash can dislodge residents from the littoral zone. With the intertidal zone's high exposure to sunlight, the temperature can range from very hot with full sunshine to near freezing in colder climates. Some microclimates in the littoral zone are moderated by local features and larger plants such as mangroves. Adaptation in the littoral zone allows the use of nutrients supplied in high volume on a regular basis from the sea, which is actively moved to the zone by tides. Edges of habitats, in this case land and sea, are themselves often significant ecologies, and the littoral zone is a prime example.

A typical rocky shore can be divided into a spray zone or splash zone (also known as the supratidal zone), which is above the spring high-tide line and is covered by water only during storms, and an intertidal zone, which lies between the high and low tidal extremes. Along most shores, the intertidal zone can be clearly separated into the following subzones: high tide zone, middle tide zone, and low tide zone. The intertidal zone is one of a number of marine biomes or habitats, including estuary, neritic, surface, and deep zones.

Ecology
Main article: Intertidal ecology

See also: Intertidal fish and Tide pool A California tide pool in the low tide zone

The intertidal region is an important model system for the study of ecology, especially on wave-swept rocky shores. The region contains a high diversity of species, and the zonation created by the tides causes species ranges to be compressed into very narrow bands. This makes it relatively simple to study species across their entire cross-shore range, something that can be extremely difficult in, for instance, terrestrial habitats that can stretch thousands of kilometres. Communities on wave-swept shores also have high turnover due to disturbance, so it is possible to watch ecological succession  over years rather than decades.

The burrowing invertebrates that make up large portions of sandy beach ecosystems are known to travel relatively great distances in cross-shore directions as beaches change on the order of days, semilunar cycles, seasons, or years. The distribution of some species has been found to correlate strongly with geomorphic datums such as the high tide strand and the water table outcrop.

Since the foreshore is alternately covered by the sea and exposed to the air, organisms living in this environment must have adaptions for both wet and dry conditions. Intertidal zone biomass does reduce the risk of shoreline erosion from high intensity waves. Typical inhabitants of the intertidal rocky shore include urchins, sea anemones, barnacles, chitons, crabs, isopods, mussels, starfish, and many marine gastropod molluscs such as limpets and whelks. Sexual and asexual reproduction varies by inhabitants of the intertidal zones. Sea anemones are one of the only species that can perform sexual and asexual reproduction in intertidal zones..

Humans have historically used intertidal zones as foraged food sources during low tide. Migratory birds also rely on intertidal species for feeding areas because of low water habitats consisting of an abundance of mollusks and other marine species.

Legal issues
See also: Public trust doctrine

As with the dry sand part of a beach, legal and political disputes can arise over the ownership and use of the foreshore. One recent example is the New Zealand foreshore and seabed controversy. In legal discussions, the foreshore is often referred to as the wet-sand area.

For privately owned beaches in the United States, some states such as Massachusetts use the low-water mark as the dividing line between the property of the State and that of the beach owner; however the public still has fishing, fowling, and navigation rights to the zone between low and high water. Other states such as California use the high-water mark.

In the United Kingdom, the foreshore is generally deemed to be owned by the Crown although there are notable exceptions, especially what are termed several fisheries, which can be historic deeds to title, dating back to King John's time or earlier, and the Udal Law, which applies generally in Orkney and Shetland.

In Greece, according to the L. 2971/01, the foreshore zone is defined as the area of the coast that might be reached by the maximum climbing of the waves on the coast (maximum wave run-up on the coast) in their maximum capacity (maximum referring to the "usually maximum winter waves" and of course not to exceptional cases, such as tsunamis  etc.). The foreshore zone, a part of the exceptions of the law, is public, and permanent constructions are not allowed on it.

In the East Africa and West Indian Ocean, intertidal zone management is often neglected of being a priority due to there being no intent for collective economic productivity. According to workshops performing questionaries, it is stated that eighty-six percent of respondents believe mismanagement of mangrove and coastal ecosystems are due to lack of knowledge to steward the ecosystems, yet forty-four percent of respondents state that there is a fair amount of knowledge used in those regions for fisheries.

Threats
See Also: Ocean Climate Change Intertidal zones are sensitive habitats with an abundance of marine species, that can experience ecological hazards associated with tourism and human-induced environmental impacts. A variety of other threats that have been summarized by scientists include nutritional pollution, over harvesting, habitat destruction, and climate change. Habitat destruction is advanced through activities including harvesting fisheries with drag nets and neglect of the sensitivity of them.

Oil spills, micro plastics, agricultural runoff, and untreated sewage cause of dead zones and estuary sickness in foreshore areas. Chemical composition of intertidal zones also effect temperature changes and oxygenated water- depletion of oxygen and abnormal temperatures can harm reproductive health, available nutrients to animals of the foreshore. Other hazards include being smashed or carried away by rough waves, and marine species exposure to dangerously high temperatures and desiccation.

External links[edit]

 * Enchanted Learning
 * Encyclopædia Britannica
 * Watch the online documentary The Intertidal Zone