The Inter Tidal Zone

The intertidal zone (also known as the foreshore and seashore and sometimes referred to as the littoral zone) is the area that is exposed to the air at low tide and underwater at high tide (for example, the area between tide marks). This area can include many different types of habitats, including steep rocky cliffs, sandy beaches, 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 slope interacts with high tidal excursion. Organisms in the intertidal zone are adapted to an environment of harsh extremes. Water is available regularly with the tides but varies from fresh with rain to highly saline and dry salt with drying between tidal inundations. The action of waves can dislodge residents in the littoral zone. With the intertidal zone's high exposure to the sun the temperature range can be anything from very hot with full sun to near freezing in colder climates. Some microclimates in the littoral zone are ameliorated by local features and larger plants such as mangroves. Adaption in the littoral zone is for making 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. Zonation A rock, seen at low tide, exhibiting typical intertidal zonation, Kalaloch, Washington, western USA. Marine biologists and others divide the intertidal region into three zones (low, middle, and high), based on the overall average exposure of the zone. 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 swash 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 region above the high tide line. Depending on the substratum and topography of the shore, additional features may be noticed. On rocky shores, tide pools form at low tide when water is trapped in hollows. Under certain conditions, such as those at Morecambe Bay, quicksand may form. 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; the most notable difference with this subregion to 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, anemones, brown seaweed, chitons, crabs, green algae, hydroids, isopods, limpets, mussels, nudibranchs, sculpin, sea cucumber, sea lettuce, sea palms, sea stars, 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 localised ecosystem and because 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 light 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 large fish because of the wave action and the water still being relatively shallow. Ecology Low tide zone in California Tide pools. The intertidal region is an important model systems for the study of ecology, especially on wave-swept rocky shores. The region contains a high diversity of species, and the different zones caused by the physics of 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 kilometers. 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.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. Hazards include being smashed or carried away by rough waves, exposure to dangerously high temperatures, and desiccation. Typical inhabitants of the intertidal rocky shore include sea anemones, barnacles, chitons, crabs, isopods, mussels, seastars, and many marine gastropod mollusks such as limpets, whelks etc. Also see tide pool. Ecology Two specific environmental requirements dominate seaweed ecology. These are the presence of seawater (or at least brackish water) and the presence of light sufficient to drive photosynthesis. Another common requirement is a firm attachment point. As a result, seaweeds most commonly inhabit the littoral zone and within that zone more frequently on rocky shores than on sand or shingle. Seaweeds occupy a wide range of ecological niches. The highest elevation is only wetted by the tops of sea spray, the lowest is several meters deep. In some areas, littoral seaweeds can extend several miles out to sea. The limiting factor in such cases is sunlight availability. The deepest living seaweeds are the various kelps. A number of species such as Sargassum have adapted to a fully planktonic niche and are free-floating, depending on gas-filled sacs to maintain an acceptable depth.

Others have adapted to live in tidal rock pools. In this niche seaweeds must withstand rapidly changing temperature and salinity and even occasional drying.[2] Uses:Seaweed has a variety of purposes, for which it is farmed[3] or foraged from the wild.[4] Food Main article: Edible seaweed:Seaweeds are consumed by coastal people, particularly in East Asia, e.g., Japan, China, Korea, Taiwan, Thailand, and Vietnam, but also in Indonesia, Belize, Peru, the Canadian Maritimes, Scandinavia, Ireland, Wales, Philippines, and Scotland. Tiwi, Albay residents discovered a new pancit or noodles made from seaweed, which has health benefits. It is rich in calcium and magnesium and seaweed noodles can be cooked into pancit canton, pancit luglug, spaghetti or carbonara.[5] In Asia, Zicai (紫菜) (in China), gim (in Korea) and nori (in Japan) are sheets of dried Porphyra used in soups or to wrap sushi. Chondrus crispus (commonly known as Irish moss or carrageenan moss) is another red alga used in producing various food additives, along with Kappaphycus and various gigartinoid seaweeds. Porphyra is a red alga used in Wales to make laver. Laverbread, made from oats and the laver, is a popular dish there. Affectionately called "Dulce" in northern Belize, seaweeds are mixed with milk, nutmeg, cinnamon, and vanilla to make a common beverage. Seaweeds are also harvested or cultivated for the extraction of alginate, agar and carrageenan, gelatinous substances collectively known as hydrocolloids or phycocolloids. Hydrocolloids have attained commercial significance as food additives.[6] The food industry exploits their gelling, water-retention, emulsifying and other physical properties. Agar is used in foods such as confectionery, meat and poultry products, desserts and beverages and moulded foods. Carrageenan is used in salad dressings and sauces, dietetic foods, and as a preservative in meat and fish products, dairy items and baked goods. Medicine:Alginates are used in wound dressings, and production of dental moulds. In microbiology research, agar is extensively used as culture medium.[citation needed] Seaweed is a source of iodine,[7] necessary for thyroid function and to prevent goitre. Seaweeds may have curative properties for tuberculosis, arthritis, colds and influenza, worm infestations and even tumors.[1][dubious – discuss]

Seaweed extract is used in some diet pills.[8][9] [10] Other seaweed pills exploit the same effect as gastric banding, expanding in the stomach to make the body feel more full. [11][12] Other uses:Other seaweeds may be used as fertilizer.[citation needed] Seaweed is currently under consideration as a potential source of bioethanol.[13][14] Seaweed is an ingredient in some toothpaste, cosmetics and paints.[3] Alginates enjoy many of the same uses as carrageenan, and are used in industrial products such as paper coatings, adhesives, dyes, gels, explosives and in processes such as paper sizing, textile printing, hydro-mulching and drilling.