Managing seagrass meadows requires an integrated approach (31), including efforts to avoid excessive nutrient and organic inputs from agricultural, aquaculture, and urban sources and to prevent sediment loading, which causes a deterioration in the submarine light climate so critical for seagrass growth. Hundreds of species live in the seagrass near the Smithsonian Marine Station at Fort Pierce in Florida. Although they often receive little attention, they are one of the most productive ecosystems in the world. Seagrasses form the basis of one of the most productive ecosystems of the world, providing food and shelter to a diverse community of animals. The clumps are moved by currents until they land on the pistil of a female flower and fertilization takes place. Roots grow down from the rhizome to anchor the plant to the seabed, while flexible blades grow straight up and can bend to the current without resistance. Seagrasses belong to a group of plants called monocotyledons that include grasses, lilies and palms. Seagrasses are submerged flowering plants that live in shallow coastal waters. Larkum, R.J. Orth and C.M. Seagrasses have evolved to withstand various degrees of salinity. Aquatic plants have slightly different anatomy than land plants that would make living out of the water difficult. Sewage, oil spills and agricultural and industrial waste pollute the water and make it murky. By working together, these international science teams hope to not only understand how these critical coastal habitats work, but how to best protect them and ensure their existence in the future. Unlike flowering plants on land, however, they lack stomata—the tiny pores on leaves that open and close to control water and gas exchange. Globally, 30,000km 2 of seagrass has been lost in the last couple of decades which is equal to 18% of the global area. The value of the world’s ecosystem services and natural capital (PDF) - Robert Costanza, Ralph D’Arge, Rudolf de Groot, et al. Seagrasses are often called foundation plant species or ecosystem engineers because they modify their environments to create unique habitats. They evolved around 100 million years ago, and today there are approximately 72 different seagrass species that belong to four major groups. It acts as a carbon sink by absorbing carbon dioxide, while producing oxygen through photosynthesis. Seagrass species come in many different shapes and sizes, as illustrated by this conceptual diagram of some common seagrass species. There are 50 – 60 seagrass species worldwide. New report enables creation of carbon credits for restored wetlands (Smithsonian Science News) But it's what they do in their native habitat that has the biggest benefits for humans and the ocean. one of the most valuable ecosystems on the planet, fishermen will specifically seek out seagrass beds, this diversity itself is linked to higher animal abundances, lost globally at a rate of 1.5 percent per year, Economic Values of Coral Reefs, Mangroves, and Seagrasses, Seagrass: unsung ecological hero, potential economic powerhouse (The Science Show), New report enables creation of carbon credits for restored wetlands (Smithsonian Science News), Seagrass Restoration Paying Off for Eastern Shore (UVA Today), Carbon capture and storage: Seagrasses do it for free (ABC), Global seagrass distribution and diversity: A bioregional model, Biodiversity mediates top–down control in eelgrass ecosystems: a global comparative-experimental approach, The value of the world’s ecosystem services and natural capital (PDF), Extinction risk assessment of the world’s seagrass species. Released into the Mediterranean in the 1980s from aquaria, by 2000 it covered more than 131 square kilometers (50 square miles) of the Mediterranean coastline, overgrowing and replacing the native Neptune seagrass (Posidonia oceanica) and reducing the ecosystem's biodiversity. The ability of seagrass to reduce the speed of currents can result in pollutants accumulating in the seagrass bed. Without it, the plants die and rot, resulting in more, not less, greenhouse gases, as well as loss of habitat for … Seagrasses provide an important habitat to a number of organisms. Choose a site with well-drained soil and full sun (many grasses need at least six hours of direct sunlight every day). Even though seagrasses and seaweeds look superficially similar, they are very different organisms. Seagrass coverage is being lost globally at a rate of 1.5 percent per year. Their roots trap and stabilize the sediment, which not only helps improve water clarity and quality, but also reduces erosion and buffers coastlines against storms. Without it, the plants die and rot, resulting in more, not less, greenhouse gases, as well as loss of habitat for the other plants and animals that depended on the grass. However, it may not be able to adapt to the severe and increasing damage now being caused by human activity. They play a vital role in preserving the biodiversity of sea life, as they shelter or nourish thousands of animal or plant species, and help to keep the oceans healthy by locking away carbon and releasing oxygen. Conditions change from being underwater, to being exposed to hot sun and drying wind, within just one tidal cycle. Extinction risk assessment of the world’s seagrass species - Frederick T. Short, Beth Polidoro, Suzanne R. Livingstone, et al. Duarte While most coastal regions are dominated by one or a few seagrass species, regions in the tropical waters of the Indian and western Pacific oceans have the highest seagrass diversity with as many as 14 species growing together. There are 60 species of seagrasses worldwide, according to the National Center for Ecological Analysis and Synthesis. It has been estimated that in this way the world's seagrass meadows can capture up to 83 million metric tons of carbon each year. As well as fueling global warming, human activities directly endanger seagrass in ways that are difficult for it to adapt to. Called the Zostera Experimental Network (ZEN), this program was initiated in 2011 by the Smithsonian Institution's Tennenbaum Marine Observatories Network director Dr. Emmett Duffy. It's estimated that 29 percent of seagrass meadows have died off in the past century. Copyright 2020 Leaf Group Ltd. / Leaf Group Media, All Rights Reserved. In a 2011 assessment, nearly one quarter of all seagrass species for which information was adequate to judge were threatened (endangered or vulnerable) or near threatened using the International Union for the Conservation of Nature (IUCN) Red List criteria. Many seagrass species live in depths of 3 to 9 feet (1 to 3 meters), but the deepest growing seagrass (Halophila decipiens) has been found at depths of 190 feet (58 meters). Seagrasses can only survive in a narrow range of depth and light levels. In fact, in all regions of the world fishermen will specifically seek out seagrass beds for their abundance of fish. The salt water helps the root grow. In fact, the only marine plant listed as endangered in the United States is a seagrass (Halophila johnsonii) found in Florida. Seagrasses are so-named because most species have long green, grass-like leaves. Like other flowering plants, their roots can absorb nutrients. As a result, seagrasses can be home to many types of fish, sharks, turtles, marine mammals (dugongs and manatees), mollusks (octopus, squid, cuttlefish, snails, bivalves), sponges, crustaceans (shrimp, crabs, copepods, isopods and amphipods) polychaete worms, sea urchins and sea anemones—and the list goes on. Dead seagrasses provide food for decomposers like worms, sea cucumbers, crabs, and filter feeders. Algae on the seafloor have a holdfast and transport nutrients through the body by diffusion, while seagrasses are flowering vascular plants with roots and an internal transport system. One hectare of seagrass (about two football fields) is estimated to be worth over $19,000 per year, making them one of the most valuable ecosystems on the planet. In the early 1930s, a large die-off of up to 90 percent of all eelgrass (Zostera marina) growing in temperate North America was attributed to a "wasting disease". Scientists are studying what genes were lost and which were regained as seagrasses evolved from algae in the sea to plants on land, and then transitioned back to the sea. Green and F.T. What is a dugong? Seagrass Ecology by M. Hemming and C.M. They are in turn consumed by larger crustaceans, fish and birds and are important links in the coastal food web. Like land plants, seagrass produce oxygen. They can also tolerate temperatures ranging from minus 6 to 40 degrees C. Their horizontal stems, called rhizomes, enable them to cope with the tugging of currents and waves. Occasionally when some mesograzer species are at very high densities they can create thick masses of mucus and sediment tubes that block light to the seagrass leaves, and they can even eat the seagrass directly. Like all plants, underwater grasses need sunlight to grow, which makes improving water clarity an important step in underwater grass restoration. Seagrass Restoration Paying Off for Eastern Shore (UVA Today) When the conditions are just right, seagrasses can densely cover the sea floor, creating an ecosystem known as the seagrass bed or seagrass meadow. Seagrasses support commercial fisheries and biodiversity, clean the surrounding water and help take carbon dioxide out of the atmosphere. Seagrass helps mitigate the effects of global warming in several ways. Adapted to life in salt water by evolution from land-based plants, seagrass is constantly adapting to natural changes in the environment caused by weather and rising sea levels. Duffy, P.L. The sediment it collects helps prevent erosion and slow the rate at which land area is lost to the sea. Seagrasses are often called nursery habitats because the leafy underwater canopy they create provides shelter for small invertebrates (like crabs and shrimp and other types of crustaceans), small fish and juveniles of larger fish species. The veliger develops into a juvenile scallop in about two weeks, when it then settles from the water and attaches to seagrass blades. Seagrass responds to rising sea levels by spreading shore-wards into shallower water. As of 2015, the seagrass Zostera marina has increased from these seeded plots to cover 6,195 acres. Seagrass lacks the charisma of coral reefs or the imposing presence of mangroves. Photos (clockwise from top left) by Chris Nicolini, Matt Whalen, Jonas Thormar and Camilla Gustafsson. Because they depend on light for photosynthesis, they are most commonly found in shallow depths where light levels are high. Similarly, dredging can both directly remove seagrass plants and cause lower light levels because of increased amounts of sediments in the water. Additionally, some threatened marine species such as sea turtles and marine mammals live in seagrass habitats and rely on them for food. This die-off was so severe that a small snail specialized to live on eelgrass went extinct as a result. A number of the species that depend on seagrasses are important for commercial and recreational fisheries. For kelp to survive, it must be anchored to strong substrate, otherwise it will be yanked loose during storms. For restoration to work, it is critical that the causes of the original decline in seagrasses have been eliminated. Seagrass needs clear, sunlit water for photosynthesis. The seagrass protects the coral reef from the waves. Seagrasses are known as primary producers because they make their own food though photosynthesis, they can then be eaten by animals and so they have an important role in the food web. In areas with intact seagrass beds, storms often do less damage to coral reefs and coastal lands because the seagrasses act as a buffer, absorbing energy from the waves. Since then, invasive Caulerpa has been found in California and southwestern Australia where eradication programs are in place to prevent its spread. But, this partnership isn't always positive. They've been used to fertilize fields, insulate houses, weave furniture, thatch roofs, make bandages, and fill mattresses and even car seats. "Seagrasses have the unique ability to continue to store carbon in their roots and soil in coastal seas. It is because of the wide variety of different species that live amongst the grasses that seagrass beds often form important "biodiversity hotspots." The tallest seagrass species—Zostera caulescens—was found growing to 35 feet (7 meters) in Japan. That amounts to about 2 football fields of seagrass lost each hour. The accumulation of smaller organisms amongst and on the seagrass blades, as well as the seagrass itself, attracts bigger animals. This is especially worrying because seagrass losses are projected to have severe impacts on marine biodiversity, the health of other marine ecosystems, and on human livelihoods. Protecting and promoting the growth of seagrass, therefore, represents a way for coastal communities -- human, plant and animal -- to cope with some of the effects of climate change. To survive, all seagrasses need is clean water, sunlight and sand or mud to grow in, but life between land and sea isn't easy. Some simple steps everyone can take to help seagrasses and other marine habitats include: don't litter, limit the amount of fertilizer and pesticides you use, don't dump anything hazardous down the drain, be careful when boating by going slow and avoiding shallow areas, and support local conservation efforts. The newer Thalassia Experimental Network (TEN), run by scientists working with the Smithsonian Institution's MarineGEO program, uses similar approaches to test those questions in tropical Thalassia testudinum habitats in the Florida Keys, Panama and Belize. Some organisms—primarily large grazers like manatees, dugongs, green sea turtles and geese—eat the living leaves directly, and seagrass forms a major component of their diets. They cannot grow easily where they dry out at low tide. Rising water temperatures tend to increase rates of seagrass respiration (using up oxygen) faster than rates of photosynthesis (producing oxygen), which makes them more susceptible to grazing by herbivores. The 72 species of seagrasses are commonly divided into four main groups: Zosteraceae, Hydrocharitaceae, Posidoniaceae and Cymodoceaceae. Seagrasses grow in salty and brackish (semi-salty) waters around the world, typically along gently sloping, protected coastlines. These abundant large grazers probably kept seagrass meadows cropped short like a putting green. Several different species of plants, representing at least four distinct families, are collectively known as the seagrasses, so the term does not accurately describe an individual group of plants. Biodiversity mediates top–down control in eelgrass ecosystems: a global comparative-experimental approach - J.E. Many of these large grazers are endangered, in large part because of habitat destruction and hunting, but once they were very common. They are often confused with seaweeds, but are actually more closely related to the flowering plants that you see on land. Seagrasses support commercial fisheries and biodiversity, clean the surrounding water and help take carbon dioxide out of the atmosphere. When the leaves die, they decay on the sediment or are washed onto the beach, supporting a diverse community of decomposers that thrive on rotting material. The best time for planting perennial grasses is in the spring or fall. If meadows are removed, thousands of species could be left starving, homeless, or both. The dugong (Dugong dugon) is the only herbivorous marine mammal. Seagrasses grow both vertically and horizontally—their blades reach upwards and their roots down and sideways—to capture sunlight and nutrients from the water and sediment. Several heavy metals have been found to reduce the plant's ability to fix nitrogen, reducing its ability to survive. Many are endangered. Marine Life Found in Seagrass Beds . Many species of algae and microalgae (such as diatoms), bacteria and invertebrates grow as “epiphytes” directly on living seagrass leaves, much like lichens and Spanish moss grow on trees. Temperature affects how enzymes and metabolism work, influencing how organisms grow. Some fast growing seagrass meadows are able to rebound from disturbances, but many grow slowly over the course of centuries and are likely to be slow to recover and are thus most vulnerable. Seagrasses provide many important services to people as well, but many seagrasses meadows have been lost because of human activities. There are also attempts to rebuild and restore seagrass beds, often by planting seeds or seedlings grown in aquaria, or transplanting adult seagrasses from other healthy meadows. This involves mapping, monitoring and analysis so that programs of education and conservation can be planned in the most effective way. The depth at which seagrass are found is limited by water clarity, which determines the amount of light reaching the plant. The darker shades of green indicate more species are present. Seagrass: unsung ecological hero, potential economic powerhouse (The Science Show) This disease still affects eelgrass populations in the Atlantic and has contributed to some recent losses, though none as catastrophic as in the 1930s. Some of these organisms are permanent residents in seagrass meadows, while others are temporary visitors. Because of these benefits, seagrasses are believed to be the third most valuable ecosystem in the world (only preceded by estuaries and wetlands). It stabilizes the seabed, protecting coastlines from erosion and storm damage. As parts of the seagrass plants and associated organisms die and decay, they can collect on the seafloor and become buried, trapped in the sediment. Animals that eat seagrass seeds—including fish and turtles—may incidentally aid with their dispersal and germination if the seeds pass through their digestive tracks and remain viable. The dugong that live in these seagrass ecosystems are excellent barometers indicative of the overall health of the ecosystem. Light is required for the plants to make food through photosynthesis. They have no flowers or veins, and their holdfasts simply attach to the bottom and are generally not specialized to take in nutrients. (From "Tropical Connections: South Florida's marine environment" (pg. Shades of green indicate the number of species reported for a given area. Male seagrass flowers release pollen from structures called stamens into the water. However, seagrass populations globally are still in trouble. Unfortunately, seagrass is often buried by sediment or nutrient runoff, ripped up to make navigation channels or docks, or drowned by climate change. (Antoine N'Yeurt, Moorea Biocode Project ). Episodes of warm seawater temperatures can also damage seagrasses. A healthy watershed means healthy seagrass. There is no international legislation for seagrasses, and so protection typically occurs by local and regional agencies. The habitat must provide the organisms within it with what they need for survival such as food, water oxygen and minerals. Short and R.G. Work is ongoing around the world to restore these important ecosystems. Unfortunately, seagrasses are in trouble. Dead seagrass leaves also play an important role in coastal ecosystems. Seagrass needs clear, sunlit water for photosynthesis. These scientists conduct coordinated, simultaneous surveys and experiments in eelgrass habitats at 50 locations across the Northern Hemisphere to address those questions. Powered by Create your own unique website with customizable templates. Sea grasses are halophytes (salt loving plants) and can store sodium in their vacuoles. Seagrasses range from species with long flat blades that look like ribbons to fern or paddle-shaped leaves, cylindrical or spaghetti blades, or branching shoots. Disease has also devastated seagrasses. Seagrasses have roots, stems and leaves, and produce flowers and seeds. When this happens, many stems within the same meadow can actually be part of the same plant and will have the same genetic code—which is why it is called clonal growth. Chloroplasts in their tissues use the sun's energy to convert carbon dioxide and water into sugar and oxygen for growth through the process of photosynthesis. Seagrass is a very difficult environment to restore, so once gone, these underwater meadows will have a hard time coming back. Self-pollination happens in some grass species, which can reduce genetic variation. They've been used to fertilize fields, insulate houses, weave furniture, thatch roofs, make bandages, and fill mattresses and even car seats. Actions taken to help seagrasses include limiting damaging practices such as excessive trawling and dredging, runoff pollution and harmful fishing practices (such as dynamite or cyanide fishing). However, living mats of seagrass usually help protect the shoreline by diffusing the violence of waves, and seagrass does grow back eventually. Some animals, such as skates and rays, disturb the rhizomes and roots of seagrasses, ripping up the seagrass as they forage for buried clams and other invertebrates. The carbon stored in sediments from coastal ecosystems including seagrass meadows, mangrove forests and salt marshes is known as "blue carbon" because it is stored in the sea. In fact, the oldest known plant is a clone of the Mediterranean seagrass Posidonia oceanica, which may be up to 200,000 years old, dating back to the ice ages of the late Pleistocene. Seagrasses are found in shallow salty and brackish waters in many parts of the world, from the tropics to the Arctic Circle. Algae or "seaweeds" (left) differ from seagrasses (right) in several ways. Yet despite its abundance, knowledge, science and conservation efforts of seagrass habitats are vastly under-represented. Veins transport nutrients and water throughout the plant, and have little air pockets called lacunae that help keep the leaves buoyant and exchange oxygen and carbon dioxide throughout the plant. Seagrasses provide food, shelter, and essential nursery areas to thousands of marine and estuarine species. Many other smaller animals feed on the epiphytes and invertebrates that live on and among seagrass blades. If we remove too many sharks, turtle populations could rise until they eat entire meadows into extinction. It would be impossible for seagrass to survive in the ocean for very long without this high salinity tolerance because the ocean has such high salt content. The entire genome of one seagrass, the eelgrass Zostera marina, was sequenced in 2016, helping us understand how these plants adapted to life in the sea, how they may respond to climate warming, and the evolution of salt tolerance in crop plants. A network of scientists are using the seagrass Zostera marina as a model species to test how biodiversity—the number of types of animal species and genetically different plants—may help protect these important plants against threats such as pollution and overfishing. Atmospheric carbon is captured by coastal mangroves, seagrasses and salt marshes at a rate five times faster than tropical forests. Seagrass meadows also provide physical habitat in areas that would otherwise be bare of any vegetation. Large eelgrass declines have been observed in the Chesapeake Bay in years in which water temperatures have persisted for several days above 30°C (86°F), the thermal limit for this species. Seagrasses need clean water and sunlight to thrive. Important Facts about Seagrasses Seagrasses are flowering plants that live submerged in the sea. Seagrass is named because of its long, narrow leaves, which bear a resemblance to some terrestrial grasses. By acting as a marine nursery, the meadows support recreational and commercial fishing as well as ecotourism. Seagrass Habitats at Indian River Lagoon – Smithsonian Marine Station at Fort Pierce, Economic Values of Coral Reefs, Mangroves, and Seagrasses – A Global Compilation 2008 (PDF), Importance of Seagrass – Florida Fish and Wildlife Conservation Commission, Seagrass Educators Handbook (PDF) - Seagrass Watch, News Articles: Antarctica is the only continent without seagrasses. The rhizomes can spread under the sediment and send up new shoots. (Courtesy of the Integration and Application Network (, University of Maryland Center for Environmental Science ). ). Duarte Coles The seagrass community needs a delicate balance to survive. Removal of fish can also lead to seagrass death by disrupting important components of the food web. For example, an adult dugong eats about 64 to 88 pounds (28 to 40 kg) of seagrass a day, while an adult green sea turtle can eat about 4.5 pounds (2 kg) per day. Underwater grasses are a critical part of the Bay ecosystem: they provide wildlife with food and habitat, add oxygen to the water, absorb nutrient pollution, trap sediment and reduce erosion. Seagrass adapts to the great barrier reef because the salt water. Seagrass seeds are neutrally buoyant and can float many miles before they settle onto the soft seafloor and germinate to form a new plant. Some warm-season grasses will do better if planted in the spring to allow the growing season to establish a good root system prior to winter. When the sea grass dies it helps to create future plant growth.-Mangroves grow behind the coral reefs. As a result, seagrass meadows have gone largely unnoticed. These seagrass "meadows" are home to … Other invertebrates grow nestled between the blades or in the sediments—such as sponges, clams, polychaete worms and sea anemones. Fertilized eggs develop into a swimming larval stage known as a veliger. Because of their ecologic importance and global distribution, seagrass are important study systems for understanding how coastal habitats work and respond to environmental changes. To grow, seagrasses need nutrients, often obtained from nearby mangroves, and good light, which means clear water. Seagrasses don't just provide shelter for free-swimming animals, but also are a habitat for non-moving organisms, such as these sea anemones. Some epiphytic bacteria can extract nitrogen from the environment and make it available to larger animals. Sexual Reproduction: Seagrasses reproduce sexually like terrestrial grasses, but pollination for seagrasses is completed with the help of water. Seagrasses are major structuring components of some of the most productive marine ecosystems. Seagrasses provide shelter and food to an incredibly diverse community of animals, from tiny invertebrates to large fish, crabs, turtles, marine mammals and birds. Replanting can help, but must be supported by improvements in water quality and regulation of activities like boating and building, so that the seagrass has a chance to thrive. Global seagrass distribution and diversity: A bioregional model - F. Short, T. Carruthers, W. Dennison, and M. Waycott Similar to how trees take carbon from the air to build their trunks, seagrasses take carbon from the water to build their leaves and roots. Seagrasses have been used by humans for over 10,000 years. Most management that protects seagrasses focuses on maintaining their biodiversity and the services these habitats provide for humans and ecosystems. Coastal development that involves dredging harbors and building sea-walls and jetties can destroy seagrass meadows and disrupt currents. Carbon capture and storage: Seagrasses do it for free (ABC), Books: Individual seagrass plants avoid this by producing only male or female flowers, or by producing the male and female flowers at different times. Larger animals such as manatees and sea turtles feed on animals that live in the seagrass beds. However, the direct and indirect effects of human activities account for most losses of seagrass beds in recent decades. One important example is the invasion of Caulerpa taxifolia, a seaweed nicknamed "the killer algae." This fragmentation of seagrass beds can increase erosion around the edges, as well as influence animal use and movement within the seagrass bed. Seagrasses improve water quality by trapping sediments, absorbing nutrients, and stabilizing sediment with their roots. These distinct structures and growth forms affect how seagrasses influence their environment and what species live in the habitats they create. Seagrasses are found across the world, from the tropics to the Arctic. Scientific Papers: One acre of seagrass can sequester 740 pounds of carbon per year (83 g carbon per square meter per year), the same amount emitted by a car traveling around 3,860 miles (6,212 km). Although most of the gametes do not survive, in a healthy population enough will survive to produce the next generation of scallops. Seagrass beds, like coral reefs, are amongst the most productive habitats in the marine environment. A Global Crisis for Seagrass Ecosystems - Robert Orth, Tim Carruthers, William Dennison, et al. These modifications not only make coastal habitats more suitable for the seagrasses themselves, but also have important effects on other animals and provide ecological functions and a variety of services for humans.