| Water Hyacinth | |
|---|---|
| Common Water Hyacinth (E. crassipes) | |
| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Monocots |
| (unranked): | Commelinids |
| Order: | Commelinales |
| Family: | Pontederiaceae |
| Genus: | Eichhornia Kunth |
| Species | |
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Seven species, including: |
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The seven species of water hyacinth comprise the genus Eichhornia. Water hyacinth are a free-floating perennial aquatic plant native to tropical and sub-tropical South America. With broad, thick, glossy, ovate leaves, water hyacinth may rise above the surface of the water as much as 1 meter in height. The leaves are 10–20 cm across, and float above the water surface. They have long, spongy and bulbous stalks. The feathery, freely hanging roots are purple-black. An erect stalk supports a single spike of 8-15 conspicuously attractive flowers, mostly lavender to pink in colour with six petals. When not in bloom, water hyacinth may be mistaken for frog's-bit (Limnobium spongia).
One of the fastest growing plants known, water hyacinth reproduces primarily by way of runners or stolons, which eventually form daughter plants. It also produces large quantities of seeds, and these are viable up to thirty years. The common water hyacinth (Eichhornia crassipes) are vigorous growers known to double their population in two weeks.
In Assamese they are known as Meteka. In Sinhala they are known as Japan Jabara (ජපන් ජබර) due to their use in World War II to fool Japanese pilots into thinking lakes were fields usable to land their aircraft, leading to crashes. In Burmese they are known as Baydar.
In Southern Pakistan, they are the provincial flower of Sindh.
In the Philippines, they use some of the water hyacinth's stems and dry it to take its fibers and take them to form strands of string each. These pieces of string are woven or interlinked together to form a braid or cord used for making bags, footwear, wreaths, hats, vases, Christmas lanterns, and more decorative materials. Because water hyacinth are prolific to the point of being a nuisance, this lets the people earn money by selling these products for a living while cleaning up the overpopulated bodies of water that are full of water hyacinths.
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Water hyacinth has been widely introduced throughout North America, Asia, Australia and Africa. They can be found in large water areas such as Louisiana, or in the Kerala Backwaters in India. In many areas it, particularly E. crassipes, is an important and pernicious invasive species. First introduced to North America in 1884, an estimated 50 kilograms per square metre of hyacinth once choked Florida's waterways, although the problem there has since been mitigated. When not controlled, water hyacinth will cover lakes and ponds entirely; this dramatically impacts water flow, blocks sunlight from reaching native aquatic plants, and starves the water of oxygen, often killing fish (or turtles). The plants also create a prime habitat for mosquitos, the classic vectors of disease, and a species of snail known to host a parasitic flatworm which causes schistosomiasis (snail fever). Directly blamed for starving subsistence farmers in Papua New Guinea, water hyacinth remains a major problem where effective control programs are not in place. Water hyacinth is often problematic in man-made ponds if uncontrolled, but can also provide a food source for gold fish, keep water clean and help to provide oxygen to man-made ponds.
Water hyacinth often invades bodies of water that have been impacted by human activities. For example, the plants can unbalance natural lifecycles in artificial reservoirs or in eutrophied lakes that receive large amounts of nutrients.
There are other uses being found for the abundant plants, such as for cattle food and in biogas production. Recently, they have also begun to be used in wastewater treatment due to their fast growth and ability to tolerate high levels of pollution. Parts of the plant are also used in the production of traditional handicrafts in Southeast Asia. In Bangladesh, farmers have started producing fertilizer using Water Hyacinth or Kochuripana as it is known there locally.
As chemical and mechanical removal is often too expensive and ineffective, researchers have turned to biological control agents to deal with water hyacinth. The effort began in the 1970s when USDA researchers released three species of weevil known to feed on water hyacinth into the United States, Neochetina bruchi, N. eichhorniae, and the water hyacinth borer Sameodes albiguttalis. Although meeting with limited success, the weevils have since been released in more than 20 other countries. However, the most effective control method remains the control of excessive nutrients and prevention of the spread of this species.
May 2010 the USDA’s Agricultural Research Service released Megamelus scutellaris as a biological control insect for the invasive waterhyacinth species. Megamelus scutellaris is a small planthopper insect native to Argentina. Researchers have been studying the effects of the biological control agent in extensive host-range studies since 2006 and concluded that the insect is highly host-specific and will not pose a threat to any other plant population other than the targeted water hyacinth. Researchers also hope that the biological control will be more resilient than existing biological controls to the herbicides that are already in place to combat the invasive water hyacinth. [2]
Botanists and gardeners carry plants with them in their travels, and experts suspect that this is how the water hyacinth came to East Africa in the 1980s. Its flowers are beautiful; it was probably brought over as an ornamental for garden ponds (United Nations News, 2000[1]). The consensus is that Water Hyacinth entered Lake Victoria from Rwanda via the river Kagera (Ambrose 1997[2]). The exact time and place of introduction has been debated, but the plant is native to South America, and therefore reached Lake Victoria due to human activity. It has spread prolifically, due to lack of natural enemies, an abundance of space, agreeable temperature conditions, and abundant nutrients (Opande et al., 2004[3]). It increased rapidly between 1992–1998, was greatly reduced by 2001, and has since resurged to a lesser degree. Management techniques include (hyacinth-eating) insect controls and manual beach cleanup efforts (Kateregga/Sterner 2007[4]). A water hyacinth infestation is seldom totally eradicated. Instead, it is a situation that must be continually managed (LVEMP, 2004[5] ) (United Nations News, 2000[1])).
Water Hyacinth affects the Lake Victorian population in many negative ways. There are economic impacts when the weed blocks boat access. The effects on transportation and fishing are immediately felt. Where the weed is prolific, there is a general increase in several diseases, as the weed creates excellent breeding areas for mosquitoes and other insects. There are increased incidents of skin rash, cough, malaria, encephalitis, bilharzias, gastro intestinal disorders, and schistosomiasis. Water hyacinth also interferes with water treatment, irrigation, and water supply (Opande et al., 2004[3])). It can smother aquatic life by deoxygenating the water, and it reduces nutrients for young fish in sheltered bays. It has blocked supply intakes for the hydroelectric plant, interrupting electrical power for entire cities. The weed also interrupts local subsistence fishing, blocking access to the beaches (LVEMP, 2004[5]).
Since the plant has abundant nitrogen content, it can be used a substrate for biogas production and the sludge obtained from the biogas. However, due to easy accumulation of toxins, the plant is prone to get contaminated when used as feed.
The plant is extremely tolerant of, and has a high capacity for, the uptake of heavy metals, including Cd, Cr, Co, Ni, Pb and Hg, which could make it suitable for the biocleaning of industrial wastewater [6], [7], [8],.[9] In addition to heavy metals, Eichhornia crassipes can also remove other toxins, such as cyanide, which is environmentally beneficial in areas that have endured gold mining operations.[10]
Water hyacinth removes arsenic from arsenic contaminated drinking water. It may be a useful tool in removing arsenic from tube well water in Bangladesh.[11]
Water hyacinth is also observed to enhance nitrification in waste water treatment cells of living technology. Their root zones are superb micro-sites for bacterial communities.[12]