The intertidal zone or foreshore is the area above water level at low tide and underwater at high tide; in other words, it is the part of the littoral zone within the tidal range. This area can include several types of habitats with various species of life, such as sea stars, sea urchins, and many species of coral with regional differences in biodiversity. Sometimes it is referred to as the littoral zone or seashore, although those can be defined as a wider region.
The intertidal zone also includes steep rocky cliffs, sandy beaches, bogs or wetlands (e.g., vast mudflats). This area can be a narrow strip, such 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 well-adapted to their environment, facing high levels of interspecific competition and the rapidly changing conditions that come with the tides.[1] The intertidal zone is also home to several species from many different phyla (Porifera, Annelida, Coelenterata, Mollusca, Arthropoda, etc.).
The water that comes with the tides 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. Adaptations in the littoral zone allow the utilization of nutrients supplied in high volume on a regular basis from the sea, which is actively moved to the zone by tides. The edges of habitats, in this case the land and sea, are themselves often significant ecosystems, 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 estuaries, the neritic zone, the photic zone, and deep zones.
Zonation
Tide pools at Pillar Point showing zonation on the edge of the rock ledgeA rock, seen at low tide, exhibiting typical intertidal zonation, Kalaloch, Washington, western United States.
Marine biologists divide the intertidal region into three zones (low, middle, and high), based on the overall average exposure of the zone.[2] The low intertidal zone, which borders on the shallow subtidal zone, is only exposed to air at the lowest of low tides and is primarily marine in character. The mid intertidal zone is regularly exposed and submerged by average tides. The high intertidal zone is only covered by the highest of the high tides, and spends much of its time as terrestrial habitat. The high intertidal zone borders on the splash zone (the region above the highest still-tide level, but which receives wave splash). On shores exposed to heavy wave action, the intertidal zone will be influenced by waves, as the spray from breaking waves will extend the intertidal zone.
Depending on the substratum and topography of the shore, additional features may be noticed. On rocky shores, tide pools form in depressions that fill with water as the tide rises. Under certain conditions, such as those at Morecambe Bay, quicksand may form.[3]
Low tide zone (lower littoral)
This subregion is mostly submerged – it is only exposed at the point of low tide and for a longer period of time during extremely low tides. This area is teeming with life;[2] the most notable difference between this subregion and the other three is that there is much more marine vegetation, especially seaweeds. There is also a great biodiversity. Organisms in this zone generally are not well adapted to periods of dryness and temperature extremes. Some of the organisms in this area are abalone, sea anemones, brown seaweed, chitons, crabs, green algae, hydroids, isopods, limpets, mussels, nudibranchs, sculpin, sea cucumber, sea lettuce, sea palms, starfish, sea urchins, shrimp, snails, sponges, surf grass, tube worms, and whelks. Creatures in this area can grow to larger sizes because there is more available energy in the localized ecosystem. Also, marine vegetation can grow to much greater sizes than in the other three intertidal subregions due to the better water coverage. The water is shallow enough to allow plenty of sunlight to reach the vegetation to allow substantial photosynthetic activity, and the salinity is at almost normal levels. This area is also protected from large predators such as fish because of the wave action and the relatively shallow water.
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 be adapted to both wet and dry conditions. Intertidal zone biomass reduces the risk of shoreline erosion from high intensity waves.[4] Typical inhabitants of the intertidal rocky shore include sea urchins, sea anemones, barnacles, chitons, crabs, isopods, mussels, starfish, and many marine gastropodmolluscs such as limpets and whelks. Sexual and asexual reproduction varies by inhabitants of the intertidal zones.[5]
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.[4]
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, with exceptions for 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). The foreshore zone, a part of the exceptions of the law, is public, and permanent constructions are not allowed on it. In Italy, about half the shoreline is owned by the government but leased to private beach clubs called lidos.[6]
In the East African and West Indian Ocean, intertidal zone management is often neglected of being a priority due to there being no intent for collective economic productivity.[7] 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. [citation needed]
Nutrition (Eutrophic) Pollution in Assateague Island National Seashore, Maryland
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 nutrient pollution, overharvesting, habitat destruction, and climate change.[8] Habitat destruction is advanced through activities including harvesting fisheries with drag nets and a neglect of the sensitivity of intertidal zones.[9]
Gallery
Mussels in the intertidal zone in Cornwall, England
Barnacles and limpets in the intertidal zone near Newquay, Cornwall, England.
A tidal pool in the intertidal zone during low tide, Sunrise-on-Sea, South Africa
Unexplained crumbs of sand that appear to have been deposited around stone by escaping air
Rocks in intertidal zone completely covered by mussels, at Bangchuidao Scenic Area, Dalian, Liaoning Province, China
A coast – also called the coastline, shoreline, or seashore – is the land next to the sea or the line that forms the boundary between the land and the ocean or a lake. Coasts are influenced by the topography of the surrounding landscape, as well as by water induced erosion, such as waves. The geological composition of rock and soil dictates the type of shore that is created. Earth contains roughly 620,000 km (390,000 mi) of coastline.
The littoral zone, also called litoral or nearshore, is the part of a sea, lake, or river that is close to the shore. In coastal ecology, the littoral zone includes the intertidal zone extending from the high water mark, to coastal areas that are permanently submerged — known as the foreshore — and the terms are often used interchangeably. However, the geographical meaning of littoral zone extends well beyond the intertidal zone to include all neritic waters within the bounds of continental shelves.
A tide pool or rock pool is a shallow pool of seawater that forms on the rocky intertidal shore. These pools typically range from a few inches to a few feet deep and a few feet across. Many of these pools exist as separate bodies of water only at low tide, as seawater gets trapped when the tide recedes. Tides are caused by the gravitational pull of the sun and moon. A tidal cycle is usually about 25 hours and consists of one or two high tides and two low tides.
Intertidal ecology is the study of intertidal ecosystems, where organisms live between the low and high tide lines. At low tide, the intertidal is exposed whereas at high tide, the intertidal is underwater. Intertidal ecologists therefore study the interactions between intertidal organisms and their environment, as well as between different species of intertidal organisms within a particular intertidal community. The most important environmental and species interactions may vary based on the type of intertidal community being studied, the broadest of classifications being based on substrates—rocky shore and soft bottom communities.
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.
Beach wrack or marine wrack is organic material and other debris deposited at high tide on beaches and other coastal area. This material acts as a natural input of marine resources into a terrestrial system, providing food and habitat for a variety of coastal organisms.
The Davenport Tide Pools are located just past the town of Davenport, California in the United States. They are located where Davenport Landing Road loops to the sea off Highway 1. Parallel ridges running perpendicular to the sea separate the tide pools from each other and make them unique, producing communities in which organisms which normally could not live in close proximity to each other can do so. The beach is day use only, open sunrise to sunset.
This is a glossary of terms used in fisheries, fisheries management and fisheries science.
Seashore wildlife habitats exist from the Tropics to the Arctic and Antarctic. Seashores and beaches provide varied habitats in different parts of the world, and even within the same beach. Phytoplankton is at the bottom of some food chains, while zooplankton and other organisms eat phytoplankton. Kelp is also autotrophic and at the bottom of many food chains. Coastal areas are stressed through rapid changes, for example due to tides.
Lottia gigantea, common name the owl limpet, is a species of sea snail, a true limpet, a marine gastropod mollusc in the family Lottiidae. Its genome has been sequenced at the Joint Genome Institute.
Lottia digitalis, commonly known as the fingered limpet or ribbed limpet, is a species of sea snail, a true limpet, a marine gastropod mollusk in the family Lottiidae. These limpets are usually found on the surface of rocks in the high intertidal region on the coastal fringes of the north-eastern Pacific Ocean.
Lottia scabra or the rough limpet is a species of sea snail, a true limpet, a marine gastropod mollusk in the family Lottiidae.
Cape Rodney-Okakari Point Marine Reserve is a 5.5 km2 (2.1 sq mi) protected area in the North Island of New Zealand. All fishing, and the removal or disturbing of marine life or materials, is forbidden within the reserve.
A marine habitat is a habitat that supports marine life. Marine life depends in some way on the saltwater that is in the sea. A habitat is an ecological or environmental area inhabited by one or more living species. The marine environment supports many kinds of these habitats.
Stichaster australis, the reef starfish, is a species of starfish found in the shallow waters of the rocky intertidal of New Zealand. Typically, the animal is endemic to the west coast shores of the North and South Islands, where wave action is increased. They do not usually inhabit ecosystems that have reduced wave action and calm conditions as they prefer a higher-energy environment. These marine invertebrates range in color from pink to purple, but can also be orange. They typically have eleven arms, but sometimes they may have either ten or twelve. As full-grown adults, they are 8 to 10 cm in diameter.
At a flat coast or flat shoreline, the land descends gradually into the sea. Flat coasts can be formed either as a result of the sea advancing into gently sloping terrain or through the abrasion of loose rock. They may be basically divided into two parallel strips: the shoreface and the beach.
The Helderberg Marine Protected Area is a small marine conservation area on the north-eastern side of False Bay in the Western Cape province of South Africa, It lies between the mouths of the Lourens River in the Strand, and the Eerste River in Macassar.
The Hluleka Marine Protected Area is an inshore conservation region in the territorial waters of the Eastern Cape province of South Africa.
The Pondoland Marine Protected Area is an inshore conservation region in the territorial waters of South Africa.
The Stilbaai Marine Protected Area is an inshore conservation region in the territorial waters near Stilbaai on the south coast of the Western Cape province of South Africa.
References
↑ US Department of Commerce, National Oceanic and Atmospheric Administration. "What is the intertidal zone?". oceanservice.noaa.gov. Retrieved 2022-11-29.
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