SeagrassSeagrasses are the only flowering plants which grow in marine environments. There are about 60 species of fully marine seagrasses which belong to four families (Posidoniaceae, Zosteraceae, Hydrocharitaceae and Cymodoceaceae), all in the order Alismatales (in the clade of monocotyledons). Seagrasses evolved from terrestrial plants which recolonised the ocean 70 to 100 million years ago. The name seagrass stems from the many species with long and narrow leaves, which grow by rhizome extension and often spread across large "meadows" resembling grassland; many species superficially resemble terrestrial grasses of the family Poaceae.
Seagrass meadowA seagrass meadow or seagrass bed is an underwater ecosystem formed by seagrasses. Seagrasses are marine (saltwater) plants found in shallow coastal waters and in the brackish waters of estuaries. Seagrasses are flowering plants with stems and long green, grass-like leaves. They produce seeds and pollen and have roots and rhizomes which anchor them in seafloor sand. Seagrasses form dense underwater meadows which are among the most productive ecosystems in the world.
Marine habitatA marine habitat is a habitat that supports marine life. Marine life depends in some way on the saltwater that is in the sea (the term marine comes from the Latin mare, meaning sea or ocean). A habitat is an ecological or environmental area inhabited by one or more living species. The marine environment supports many kinds of these habitats. Marine habitats can be divided into coastal and open ocean habitats. Coastal habitats are found in the area that extends from as far as the tide comes in on the shoreline out to the edge of the continental shelf.
Zostera marinaZostera marina is a flowering vascular plant species as one of many kinds of seagrass, with this species known primarily by the English name of eelgrass with seawrack much less used, and refers to the plant after breaking loose from the submerged wetland soil, and drifting free with ocean current and waves to a coast seashore. It is a saline soft-sediment submerged plant native to marine environments on the coastlines of northern latitudes from subtropical to subpolar regions of North America and Eurasia.
Dead zone (ecology)Dead zones are hypoxic (low-oxygen) areas in the world's oceans and large lakes. Hypoxia occurs when dissolved oxygen (DO) concentration falls to or below 2 mg of O2/liter. When a body of water experiences hypoxic conditions, aquatic flora and fauna begin to change behavior in order to reach sections of water with higher oxygen levels. Once DO declines below 0.5 ml O2/liter in a body of water, mass mortality occurs. With such a low concentration of DO, these bodies of water fail to support the aquatic life living there.
Marine coastal ecosystemA marine coastal ecosystem is a marine ecosystem which occurs where the land meets the ocean. Marine coastal ecosystems include many very different types of marine habitats, each with their own characteristics and species composition. They are characterized by high levels of biodiversity and productivity. For example, estuaries are areas where freshwater rivers meet the saltwater of the ocean, creating an environment that is home to a wide variety of species, including fish, shellfish, and birds.
PhotosynthesisPhotosynthesis (ˌfoʊtəˈsɪnθəsɪs ) is a biological process used by many cellular organisms to convert light energy into chemical energy, which is stored in organic compounds that can later be metabolized through cellular respiration to fuel the organism's activities. The term usually refers to oxygenic photosynthesis, where oxygen is produced as a byproduct, and some of the chemical energy produced is stored in carbohydrate molecules such as sugars, starch and cellulose, which are synthesized from endergonic reaction of carbon dioxide with water.
Boundary layerIn physics and fluid mechanics, a boundary layer is the thin layer of fluid in the immediate vicinity of a bounding surface formed by the fluid flowing along the surface. The fluid's interaction with the wall induces a no-slip boundary condition (zero velocity at the wall). The flow velocity then monotonically increases above the surface until it returns to the bulk flow velocity. The thin layer consisting of fluid whose velocity has not yet returned to the bulk flow velocity is called the velocity boundary layer.
LeafA leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, flower, and fruit collectively form the shoot system. In most leaves, the primary photosynthetic tissue is the palisade mesophyll and is located on the upper side of the blade or lamina of the leaf but in some species, including the mature foliage of Eucalyptus, palisade mesophyll is present on both sides and the leaves are said to be isobilateral.
DugongThe dugong (ˈd(j)uːɡɒŋ; Dugong dugon) is a marine mammal. It is one of four living species of the order Sirenia, which also includes three species of manatees. It is the only living representative of the once-diverse family Dugongidae; its closest modern relative, Steller's sea cow (Hydrodamalis gigas), was hunted to extinction in the 18th century. The dugong is the only sirenian in its range, which spans the waters of some 40 countries and territories throughout the Indo-West Pacific.
SireniaThe Sirenia (saɪ'riːni.@ ), commonly referred to as sea cows or sirenians, are an order of fully aquatic, herbivorous mammals that inhabit swamps, rivers, estuaries, marine wetlands, and coastal marine waters. The extant Sirenia comprise two distinct families: Dugongidae (the dugong and the now extinct Steller's sea cow) and Trichechidae (manatees, namely the Amazonian manatee, West Indian manatee, and West African manatee) with a total of four species. The Protosirenidae (Eocene sirenians) and Prorastomidae (terrestrial sirenians) families are extinct.
ZosteraZostera is a small genus of widely distributed seagrasses, commonly called marine eelgrass, or simply seagrass or eelgrass, and also known as seaweed by some fishermen and recreational boaters including yachtsmen. The genus Zostera contains 15 species. Zostera marina is found on sandy substrates or in estuaries, usually submerged or partially floating. Most Zostera are perennial. They have long, bright green, ribbon-like leaves, the width of which are about . Short stems grow up from extensive, white branching rhizomes.
Marine ecosystemMarine 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 primary productionMarine primary production is the chemical synthesis in the ocean of organic compounds from atmospheric or dissolved carbon dioxide. It principally occurs through the process of photosynthesis, which uses light as its source of energy, but it also occurs through chemosynthesis, which uses the oxidation or reduction of inorganic chemical compounds as its source of energy. Almost all life on Earth relies directly or indirectly on primary production. The organisms responsible for primary production are called primary producers or autotrophs.
Harmful algal bloomA harmful algal bloom (HAB), or excessive algae growth, is an algal bloom that causes negative impacts to other organisms by production of natural algae-produced toxins, mechanical damage to other organisms, or by other means. HABs are sometimes defined as only those algal blooms that produce toxins, and sometimes as any algal bloom that can result in severely lower oxygen levels in natural waters, killing organisms in marine or fresh waters. Blooms can last from a few days to many months.
PhotorespirationPhotorespiration (also known as the oxidative photosynthetic carbon cycle or C2 cycle) refers to a process in plant metabolism where the enzyme RuBisCO oxygenates RuBP, wasting some of the energy produced by photosynthesis. The desired reaction is the addition of carbon dioxide to RuBP (carboxylation), a key step in the Calvin–Benson cycle, but approximately 25% of reactions by RuBisCO instead add oxygen to RuBP (oxygenation), creating a product that cannot be used within the Calvin–Benson cycle.
LightLight or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 terahertz, between the infrared (with longer wavelengths) and the ultraviolet (with shorter wavelengths). In physics, the term "light" may refer more broadly to electromagnetic radiation of any wavelength, whether visible or not. In this sense, gamma rays, X-rays, microwaves and radio waves are also light.
Ocean deoxygenationOcean deoxygenation is the reduction of the oxygen content in different parts of the ocean due to human activities. It occurs firstly in coastal zones where eutrophication has driven some quite rapid (in a few decades) declines in oxygen to very low levels. This type of ocean deoxygenation is also called "dead zones". Secondly, there is now an ongoing reduction in oxygen levels in the open ocean: naturally occurring low oxygen areas (so called oxygen minimum zones (OMZs)) are now expanding slowly.
Blue carbonBlue carbon is a term used in the climate change mitigation context that refers to "biologically driven carbon fluxes and storage in marine systems that are amenable to management." Most commonly, it refers to the role that tidal marshes, mangroves and seagrasses can play in carbon sequestration. Such ecosystems can contribute to climate change mitigation and also to ecosystem-based adaptation. When blue carbon ecosystems are degraded or lost they release carbon back to the atmosphere.
PhyllosphereIn microbiology, the phyllosphere is the total above-ground surface of a plant when viewed as a habitat for microorganisms. The phyllosphere can be further subdivided into the caulosphere (stems), phylloplane (leaves), anthosphere (flowers), and carposphere (fruits). The below-ground microbial habitats (i.e. the thin-volume of soil surrounding root or subterranean stem surfaces) are referred to as the rhizosphere and laimosphere. Most plants host diverse communities of microorganisms including bacteria, fungi, archaea, and protists .
