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 associated 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]
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 Canada and the southeast from Connecticut to Texas, and also in California. [10] By the 1990s control and management were costing millions of dollars each year. [11]
Specifically, a Florida west coast aquarium dealer shipped live Hydrilla from Sri Lanka under the common name "Indian star-vine." [12] After these plants were considered unsatisfactory, they were dumped into a canal near Tampa Bay, where they flourished. [12] By 1955, the plants found their way from Tampa to Miami as they were transported for cultivation and pet trade sale. [12] 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 U.S. [12]
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." [13] [14]
Hydrilla populations have caused economic, environmental, and ecological damage. [11] Hydrilla is known to be an aggressive and competitive plant, even out-competing and displacing native species, such as pondweeds and eelgrass. [12] [15] [16] Due to its competitive nature, Hydrilla has created monocultures, an area dominated by a singular species, rather than having a balance among many species, like in a normal ecosystem. [16]
In Australia, Hydrilla can become invasive if the nutrient levels are raised in disturbed ecosystems, though is not generally known to be problematic. [17]
Hydrilla can host a biofilm of the cyanobacteria Aetokthonos hydrillicola , which can produce the brominated neurotoxin aetokthonotoxin which is the causative agent of avian vacuolar myelinopathy, a fatal brain wasting disease of waterfowl and raptors. [18]
Hydrilla can be controlled by herbicides, as well as grass carp, [15] 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). [15] 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 holds the advantage in that it can spread efficiently through both tubers and turions. [16]
In 2011 the inlet of Cayuga Lake, one of the Finger Lakes in New York State, used the chemical herbicide endothall to try to head off a possible future disaster. The first year nearly $100,000 and numerous man-hours were spent trying to eradicate the Hydrilla infestation. Follow-up treatments were planned for at least five years. The City of Ithaca as well as other local officials are willing to pay the price because without quick action the plant could get into the lake and possibly spread to other Finger Lakes in the region. [19]
In August 2021 Hydrilla was discovered growing in a small boat marina that is connected to the Niagara River in the city of North Tonawanda New York. The New York State Department of Environmental Conservation is involved and working to contain the infestation according to local TV reports. [20]
In September 2021, according to local TV reports, 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 and severity of the 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. [21]
This abundant source of biomass is a known bioremediation hyperaccumulator of mercury, cadmium, chromium and lead, and as such can be used in phytoremediation. [22]
Aldrovanda vesiculosa, commonly known as the waterwheel plant, is the sole extant species in the flowering plant genus Aldrovanda of the family Droseraceae. The plant captures small aquatic invertebrates using traps similar to those of the Venus flytrap. The traps are arranged in whorls around a central, free-floating stem, giving rise to the common name. This is one of the few plant species capable of rapid movement.
Elodea is a genus of 6 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.
Elodea canadensis is a perennial aquatic plant, or submergent macrophyte, native to most of North America. It has been introduced widely to regions outside its native range and was first recorded from the British Isles in about 1836.
Myriophyllum aquaticum is a flowering plant, a vascular dicot, commonly called parrot's-feather and parrot feather watermilfoil.
Myriophyllum spicatum 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 a submerged aquatic plant, grows in still or slow-moving water, and 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.
Potamogeton crispus, the crisp-leaved pondweed, curly pondweed, curly-leaf pondweed or curled pondweed, is a species of aquatic plant (hydrophyte) native to Eurasia but an introduced species and often a noxious weed in North America.
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.
Egeria densa, the large-flowered waterweed or Brazilian waterweed, is a species of Egeria 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.
Hydrellia pakistanae is a species of fly in the shore fly family, Ephydridae. It is known as the Asian hydrilla leaf-mining fly. It is used as an agent of biological pest control against the noxious aquatic plant hydrilla.
Myriophyllum verticillatum, the whorl-leaf watermilfoil or whorled water-milfoil, is a native to much of North America, North Africa, and Eurasia. It closely resembles another native milfoil, called northern water milfoil Whorled water milfoil is also easily confused with four types of invasive milfoils: Eurasian water milfoil, Variable water-milfoil, Parrot feather, and hybrid water milfoil.
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.
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.
Podostemum ceratophyllum, commonly known as the hornleaf riverweed, is a species of submerged aquatic plant in the family Podostemaceae. It is native to eastern North America where it grows on hard bottoms in swiftly flowing rivers and streams and is considered a foundation species.
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.