Hydrilla | |
---|---|
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Monocots |
Order: | Alismatales |
Family: | Hydrocharitaceae |
Genus: | Hydrilla Rich. |
Species: | H. verticillata |
Binomial name | |
Hydrilla verticillata | |
Hydrilla (waterthyme) is a genus of aquatic plant, usually treated as containing just one species, Hydrilla verticillata, though some botanists divide it into several species. It is native to the cool and warm waters of the Old World in Asia, Africa and Australia, with a sparse, scattered distribution; in Australia from Northern Territory, Queensland, and New South Wales. [2] [3] [4]
The stems grow up to 1–2 m long. The leaves are arranged in whorls of two to eight around the stem, each leaf 5–20 mm long and 0.7–2 mm broad, with serrations or small spines along the leaf margins; the leaf midrib is often reddish when fresh. It is monoecious (sometimes dioecious), with male and female flowers produced separately on a single plant; the flowers are small, with three sepals and three petals, the petals 3–5 mm long, transparent with red streaks. It reproduces primarily vegetatively by fragmentation and by rhizomes and turions (overwintering), and flowers are rarely seen. [3] [5] [6] [7] They have air spaces to keep them upright.
Hydrilla has a high resistance to salinity compared to many other freshwater aquatic plants.
Hydrilla closely resembles some other related aquatic plants, including Egeria densa and Elodea canadensis . [8] Synonyms include H. asiatica, H. japonica, H. lithuanica, and H. ovalifolica.[ citation needed ]
Hydrilla verticillata is allelopathic to the common hornwort ( Ceratophyllum demersum ) and prickly hornwort ( C. muricatum ), that is, it produces compounds that inhibit growth of the latter two species. [9]
As aquatic macrophytes, Hydrilla play critical roles in the ecosystem. They influence nutrient cycles and the ecology of the body of water, as well as the sediments. [10] Hydrilla interacts with other organisms, supplying food and nutrients as well as habitats and shelters. [11]
Hydrilla can have negative impacts in aquatic communities. When abundant, they affect dissolved oxygen levels, which can lead to decline in populations of fish, invertebrates, and other plant species. [12]
Hydrilla is naturalized and invasive in the United States following release in the 1950s and 1960s from aquariums into waterways in Florida, due to the aquarium trade. [8] It is now established in parts of southern Canada and in the United States from Connecticut to Texas, and also in California. [13] By the 1990s control and management were costing millions of dollars each year. [14]
The plant was introduced when a Florida West Coast aquarium dealer shipped live Hydrilla from Sri Lanka under the common name "Indian star-vine." [15] These plants were considered unsatisfactory and were dumped into a canal near Tampa Bay, where they flourished. [15] By 1955, the plants found their way from Tampa to Miami as they were transported for cultivation and pet trade sale. [15] It is believed that several undocumented cases of accidental or careless releases followed, as there was extensive spread of the Hydrilla throughout Florida and the southeastern United States. [15]
Due to the combination of herbicide resistance, high growth rates, high ecological adaptability, dispersion ability, and low resources required, Hydrilla is able to invade almost every region of the world and spread at an alarming rate, affecting the ecosystem in a negative manner. [16] The high photosynthesis rate of Hydrilla leads to the depletion in dissolved carbon dioxide during daytime, which raises the pH, and to higher concentrations of oxygen. At night, the oxygen is used for oxidative phosphorylation, resulting in anoxia, and carbon dioxide is replenished, which in turn lowers the pH. [17]
As an invasive species in Florida, Hydrilla has become the most serious aquatic weed problem for Florida and most of the U.S. Because it was such a threat as an invasive species, one of the first cost-effective broadscale herbicide controls developed was fluridone. Unfortunately, this single-use herbicide resulted in fluridone-resistant Hydrilla. "As Hydrilla spread rapidly to lakes across the southern United States in the past, the expansion of resistant biotypes is likely to pose significant environmental challenges in the future." [18] [19]
Hydrilla populations have caused economic, environmental, and ecological damage. [14] Hydrilla is known to be an aggressive and competitive plant, out-competing and displacing native species, such as pondweeds and eelgrass. [15] [20] [21] Hydrilla has thus created monocultures, areas dominated by a single species, rather than having a balance among many species, as in a normal ecosystem. [21]
In Australia, Hydrilla can become invasive if the nutrient levels are raised in disturbed ecosystems, though is not generally known to be problematic. [22]
Hydrilla can host a biofilm of the cyanobacteria Aetokthonos hydrillicola , which can produce the brominated neurotoxin aetokthonotoxin — the causative agent of avian vacuolar myelinopathy, a fatal brain wasting disease of waterfowl and raptors. [23]
Hydrilla can be controlled by herbicides, as well as grass carp, [20] itself an invasive species in North America. Insects used as biological pest control for this plant include weevils of the genus Bagous and the Asian hydrilla leaf-mining fly (Hydrellia pakistanae). [20] Tubers pose a problem as they can lie dormant for a number of years, making it even more difficult to remove from waterways and estuaries. Hydrilla can spread efficiently through both tubers and turions. [21]
In 2011 an inlet of Cayuga Lake, one of the Finger Lakes in New York State, faced a Hydrilla introduction. The city of Ithaca and other local officials used the chemical herbicide endothall to try to head off establishment in the Finger Lakes, which would have been disastrous for their ecosystems. The first year nearly $100,000 and many man-hours were spent trying to eradicate the Hydrilla infestation. Follow-up treatments were planned for at least five years. [24]
In August 2021 Hydrilla was discovered growing in a small boat marina connected to the Niagara River in the city of North Tonawanda, New York. The New York State Department of Environmental Conservation is working to contain the infestation. [25]
In September 2021, the Connecticut River Conservancy stated that Hydrilla has been overwhelming tributary rivers, coves, inlets and riverbanks along the river for years. Kelsey Wentling, a river steward at the Connecticut River Conservancy, stated, "Hydrilla can spread through a process known as fragmentation, in which the plants, due to some sort of disruption, break apart and regrow elsewhere. Fragmentation often happens when boats go through a patch of Hydrilla. For this reason, it is critical that those using paddle boats, power boats, jet skis, and fishing equipment in the Connecticut River be aware of invasive Hydrilla and then take steps to reduce its spread." It has also been reported by local marinas and municipalities that they can no longer access certain boat slips and docks due to the density of Hydrilla. The Connecticut River Conservancy in September 2021 requested area boaters to complete a survey to help with the ongoing management of the invasive plant. [26]
This abundant source of biomass is a known bioremediation hyperaccumulator of mercury, cadmium, chromium and lead, and as such can be used in phytoremediation. [27]
Aegopodium podagraria, commonly called ground elder, is a species of flowering plant in the carrot family Apiaceae that grows in shady places. The name "ground elder" comes from the superficial similarity of its leaves and flowers to those of elder (Sambucus), which is not closely related. Other common names include herb gerard, bishop's weed, goutweed, gout wort, snow-in-the-mountain, English masterwort and wild masterwort. It is the type species of the genus Aegopodium. It is native to Europe and Asia, but has been introduced around the world as an ornamental plant, where it occasionally poses an ecological threat as an invasive exotic plant.
Elodea is a genus of eight species of aquatic plants often called the waterweeds described as a genus in 1803. Classified in the frog's-bit family (Hydrocharitaceae), Elodea is native to the Americas and is also widely used as aquarium vegetation and laboratory demonstrations of cellular activities. It lives in fresh water. An older name for this genus is Anacharis, which serves as a common name in North America.
Alternanthera philoxeroides, commonly referred to as alligator weed, is a native species to the temperate regions of South America, which includes Argentina, Brazil, Paraguay and Uruguay. Argentina alone hosts around 27 species that fall within the range of the genus Alternanthera. Its geographic range once covered only the Parana River region of South America, but it has since expanded, having been introduced to over 30 countries, such as the United States, Japan, China, Australia, New Zealand and many more. This invasive species is believed to have been accidentally introduced to these non-native regions through sediments trapped by, or attached to, tanks and cargo of ships travelling from South America to these various areas.
Myriophyllum aquaticum is a flowering plant, a vascular dicot, commonly called parrot's-feather and parrot feather watermilfoil.
The need for a clearly defined and consistent invasion biology terminology has been acknowledged by many sources. Invasive species, or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats. Invasion biology is the study of these organisms and the processes of species invasion.
Myriophyllum spicatum is a submerged aquatic plant which grows in still or slow-moving water. It is native to Europe, Asia, and North Africa, but has a wide geographic and climatic distribution among some 57 countries, extending from northern Canada to South Africa. It is considered to be a highly invasive species.
Najas minor, known as brittle naiad or brittle waternymph, is an annual aquatic plant, a submersed herb. It is native to Europe, Asia and North Africa from the Netherlands to Morocco east to Japan and the Philippines, including China, Siberia, Central Asia, Iran, Turkey, Ukraine, Germany, France Italy and a host of other countries. It is now introduced to North America and considered a weedy invasive species in the eastern half of the United States from Florida to Oklahoma to New Hampshire to Ontario to South Dakota. This plant prefers calm waters, such as ponds, reservoirs, and lakes, and is capable of growing in depths up to 4 meters.
Ceratophyllum demersum, commonly known as hornwort, rigid hornwort, coontail, or coon's tail, is a species of flowering plant in the genus Ceratophyllum. It is a submerged, free-floating aquatic plant, with a cosmopolitan distribution, native to all continents except Antarctica. It is a harmful weed introduced in New Zealand. It is also a popular aquarium plant. Its genome has been sequenced to study angiosperm evolution.
Elodea densa, the large-flowered waterweed or Brazilian waterweed, is a species of Elodea native to warm temperate South America in southeastern Brazil, Argentina, Chile and Uruguay. It is considered a problematic invasive species due to its use in home aquariums and subsequent release into non-native ecosystems.
Elodea nuttallii is a species of waterweed known by the common name western waterweed or Nuttall's waterweed. This is a perennial aquatic plant which is native to North America where it grows submersed in lakes, rivers, and other shallow water bodies. It is also found in Eurasia, where it is commonly weedy; it is not known as a weed species in its native range. It is sometimes used as an aquarium plant.
A weed is a plant considered undesirable in a particular situation, growing where it conflicts with human preferences, needs, or goals. Plants with characteristics that make them hazardous, aesthetically unappealing, difficult to control in managed environments, or otherwise unwanted in farm land, orchards, gardens, lawns, parks, recreational spaces, residential and industrial areas, may all be considered weeds. The concept of weeds is particularly significant in agriculture, where the presence of weeds in fields used to grow crops may cause major losses in yields. Invasive species, plants introduced to an environment where their presence negatively impacts the overall functioning and biodiversity of the ecosystem, may also sometimes be considered weeds.
Salvinia minima is a species of aquatic, floating fern that grows on the surface of still waterways. It is usually referred to as common salvinia or water spangles. Salvinia minima is native to South America, Mesoamerica, and the West Indies and was introduced to the United States in the 1920s–1930s. It is classified as an invasive species internationally and can be detrimental to native ecosystems. This species is similar to but should not be confused with giant salvinia, Salvinia molesta.
Limnobium laevigatum is a floating aquatic plant, and is a member of the family Hydrocharitaceae. Common names include West Indian spongeplant, South American spongeplant and Amazon or smooth frogbit. This plant was introduced to North American waterways through use in aquariums and aquascapes.
An aquatic weed harvester, also known as a water mower, mowing boat and weed cutting boat, is an aquatic machine specifically designed for inland watercourse management to cut and harvest underwater weeds, reeds and other aquatic plant life. The action of removing aquatic plant life in such a manner has been referred to as "aquatic harvesting".
Myriophyllum alterniflorum, known as alternate water-milfoil or alternateflower watermilfoil, is a species of water-milfoil. It is native to Europe and Asia,has been introduced to North America and inhabits aquatic habitat, such as ponds and streams.
Avian vacuolar myelinopathy (AVM) is a fatal neurological disease that affects various waterbirds and raptors. It is most common in the bald eagle and American coot, and it is known in the killdeer, bufflehead, northern shoveler, American wigeon, Canada goose, great horned owl, mallard, and ring-necked duck. Avian vacuolar myelinopathy is a newly discovered disease that was first identified in the field in 1994 when dead bald eagles were found near DeGray Lake in Arkansas in the United States. Since then, it has spread to four more states and infested multiple aquatic systems including 10 reservoirs. The cause of death is lesions on the brain and spinal cord. A neurotoxin called aetokthonotoxin produced by cyanobacteria causes the disease.
Fluridone is an organic compound that is used as aquatic herbicide often used to control invasive plants. It is used in the United States to control hydrilla and Eurasian watermilfoil among other species. Fluridone is sold as a solution and as a slow release solid because the herbicide level must be maintained for several weeks. The compound is a colorless solid.
Garden waste, or green waste dumping is the act of discarding or depositing garden waste somewhere it does not belong.
Aquatic plant management involves the science and methodologies used to control invasive and non-invasive aquatic plant species in waterways. Methods used include spraying herbicide, biological controls, mechanical removal as well as habitat modification. Preventing the introduction of invasive species is ideal.
Mayaca fluviatilis, also known as bog moss, is a perennial herbaceous submerged plant in the monogeneric family Mayacaceae. It is native to Central and South America, the Caribbean, and the United States where it is often sold as an aquarium plant. Through the aquatic plant trade, it has recently become naturalized in Sri Lanka, Singapore, and China. It has been identified in three locations in Australia but more populations are likely in other parts of Australia as well.