The coast, also known as the coastline, shoreline or seashore, is defined as the area where land meets the ocean, or as a line that forms the boundary between the land and the coastline. Shores 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 which is created. The Earth has around 620,000 kilometres (390,000 mi) of coastline. Coasts are important zones in natural ecosystems, often home to a wide range of biodiversity. On land, they harbor important ecosystems such as freshwater or estuarine wetlands, which are important for bird populations and other terrestrial animals. In wave-protected areas they harbor saltmarshes, mangroves or seagrasses, all of which can provide nursery habitat for finfish, shellfish, and other aquatic species. Rocky shores are usually found along exposed coasts and provide habitat for a wide range of sessile animals and various kinds of seaweeds. In physical oceanography, a shore is the wider fringe that is geologically modified by the action of the body of water past and present, while the beach is at the edge of the shore, representing the intertidal zone where there is one. Along tropical coasts with clear, nutrient-poor water, coral reefs can often be found between depths of 1–50 meters.
A mangrove is a shrub or tree that grows mainly in coastal saline or brackish water. Mangroves grow in an equatorial climate, typically along coastlines and tidal rivers. They have special adaptations to take in extra oxygen and to remove salt, which allow them to tolerate conditions that would kill most plants. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evolution in several plant families. They occur worldwide in the tropics and subtropics and even some temperate coastal areas, mainly between latitudes 30° N and 30° S, with the greatest mangrove area within 5° of the equator. Mangrove plant families first appeared during the Late Cretaceous to Paleocene epochs, and became widely distributed in part due to the movement of tectonic plates. The oldest known fossils of mangrove palm date to 75 million years ago.
The Everglades is a natural region of flooded grasslands in the southern portion of the U.S. state of Florida, comprising the southern half of a large drainage basin within the Neotropical realm. The system begins near Orlando with the Kissimmee River, which discharges into the vast but shallow Lake Okeechobee. Water leaving the lake in the wet season forms a slow-moving river 60 miles (97 km) wide and over 100 miles (160 km) long, flowing southward across a limestone shelf to Florida Bay at the southern end of the state. The Everglades experiences a wide range of weather patterns, from frequent flooding in the wet season to drought in the dry season. Throughout the 20th century, the Everglades suffered significant loss of habitat and environmental degradation.
Everglades National Park is an American national park that protects the southern twenty percent of the original Everglades in Florida. The park is the largest tropical wilderness in the United States and the largest wilderness of any kind east of the Mississippi River. An average of one million people visit the park each year. Everglades is the third-largest national park in the contiguous United States after Death Valley and Yellowstone. UNESCO declared the Everglades & Dry Tortugas Biosphere Reserve in 1976 and listed the park as a World Heritage Site in 1979, and the Ramsar Convention included the park on its list of Wetlands of International Importance in 1987. Everglades is one of only three locations in the world to appear on all three lists.
Conocarpus erectus, commonly called buttonwood or button mangrove, is a species of mangrove shrub in the family Combretaceae. It grows on shorelines in tropical and subtropical regions around the world.
Mangrove forests, also called mangrove swamps, mangrove thickets or mangals, are productive wetlands that occur in coastal intertidal zones. Mangrove forests grow mainly at tropical and subtropical latitudes because mangroves cannot withstand freezing temperatures. There are about 80 different species of mangroves, all of which grow in areas with low-oxygen soil, where slow-moving waters allow fine sediments to accumulate.
Rhizophora mangle, the red mangrove, is distributed in estuarine ecosystems throughout the tropics. Its viviparous "seeds", in actuality called propagules, become fully mature plants before dropping off the parent tree. These are dispersed by water until eventually embedding in the shallows.
Avicennia germinans, the black mangrove, is a shrub or small tree growing up to 12 meters in the acanthus family, Acanthaceae. It grows in tropical and subtropical regions of the Americas, on both the Atlantic and Pacific Coasts, and on the Atlantic Coast of tropical Africa, where it thrives on the sandy and muddy shores where seawater reaches. It is common throughout coastal areas of Texas and Florida, and ranges as far north as southern Louisiana and coastal Georgia in the United States.
Marine ecosystems are the largest of Earth's aquatic ecosystems and exist in waters that have a high salt content. These systems contrast with freshwater ecosystems, which have a lower salt content. Marine waters cover more than 70% of the surface of the Earth and account for more than 97% of Earth's water supply and 90% of habitable space on Earth. Seawater has an average salinity of 35 parts per thousand of water. Actual salinity varies among different marine ecosystems. Marine ecosystems can be divided into many zones depending upon water depth and shoreline features. The oceanic zone is the vast open part of the ocean where animals such as whales, sharks, and tuna live. The benthic zone consists of substrates below water where many invertebrates live. The intertidal zone is the area between high and low tides. Other near-shore (neritic) zones can include mudflats, seagrass meadows, mangroves, rocky intertidal systems, salt marshes, coral reefs, lagoons. In the deep water, hydrothermal vents may occur where chemosynthetic sulfur bacteria form the base of the food web.
Before drainage, the Everglades, a region of tropical wetlands in southern Florida, were an interwoven mesh of marshes and prairies covering 4,000 square miles (10,000 km2). The Everglades is both a vast watershed that has historically extended from Lake Okeechobee 100 miles (160 km) south to Florida Bay, and many interconnected ecosystems within a geographic boundary. It is such a unique meeting of water, land, and climate that the use of either singular or plural to refer to the Everglades is appropriate. When Marjory Stoneman Douglas wrote her definitive description of the region in 1947, she used the metaphor "River of Grass" to explain the blending of water and plant life.
The New Guinea mangroves is a mangrove ecoregion that covers extensive areas of the coastline New Guinea, the large island in the western Pacific Ocean north of Australia.
Tropical hardwood hammocks are closed canopy forests, dominated by a diverse assemblage of evergreen and semi-deciduous tree and shrub species, mostly of West Indian origin. Tropical hardwood hammocks are found in South Florida or the Everglades, with large concentrations on the Miami Rock Ridge, in the Florida Keys, along the northern shores of Florida Bay, and in the Pinecrest region of the Big Cypress Swamp.
Mangrove ecosystems represent natural capital capable of producing a wide range of goods and services for coastal environments and communities and society as a whole. Some of these outputs, such as timber, are freely exchanged in formal markets. Value is determined in these markets through exchange and quantified in terms of price. Mangroves are important for aquatic life and home for many species of fish.
Florida has two Level I and three Level II/III ecoregions containing more than 80 distinct ecosystems. From the northwestern panhandle to the Everglades, differences in hydrology, climate, landforms, soil types, flora, and fauna shape each ecosystem, creating a complex landscape that has been recognized as a global biodiversity hotspot.
Bruguiera cylindrica is a mangrove in the family Rhizophoraceae. It grows in mangrove swamps in tropical Asia.
Salt ponds are a natural feature of both temperate and tropical coastlines. These ponds form a vital buffer zone between terrestrial and marine ecosystems. Contaminants such as sediment, nitrates and phosphates are filtered out by salt ponds before they can reach the ocean. The depth, salinity and overall chemistry of these dynamic salt ponds fluctuate depending on temperature, rainfall, and anthropogenic influences such as nutrient runoff. The flora and fauna of tropical salt ponds differ markedly from those of temperate ponds. Mangrove trees are the dominant vegetation of tropical salt pond ecosystems, which also serve as vital feeding and breeding grounds for shore birds.
Mangrove restoration is the regeneration of mangrove forest ecosystems in areas where they have previously existed. Restoration can be defined as "the process of assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed." Mangroves can be found throughout coastal wetlands of tropical and subtropical environments. Mangroves provide essential ecosystem services such as water filtration, aquatic nurseries, medicinal materials, food, and lumber. Additionally, mangroves play a vital role in climate change mitigation through carbon sequestration and protection from coastal erosion, sea level rise, and storm surges. Mangrove habitat is declining due to human activities such as clearing land for industry and climate change. Mangrove restoration is critical as mangrove habitat continues to rapidly decline. Different methods have been used to restore mangrove habitat, such as looking at historical topography, or mass seed dispersal. Fostering the long-term success of mangrove restoration is attainable by involving local communities through stakeholder engagement.
The Petenes mangroves ecoregion covers mangrove habitat along the Gulf of Mexico coast of southern Mexico, where Campeche state and Yucatan state meet, centering on the Celestun Lagoon inland from the barrier-island town of Celestún. Because the region has relatively little rainfall and no rivers feeding the lagoons, the freshwater to support the mangrove ecosystem springs from underground aquifers. The area is important for migratory birds, and as a nesting area for sea turtles. The area around the Celestun Lagoon is protected by the Ría Celestún Biosphere Reserve, a UNESCO Biosphere Reserve, and Los Petenes Biosphere Reserve in Campeche.
Sri Lanka exhibits a remarkable biological diversity and is considered to be the richest country in Asia in terms of species concentration.
