Water Hyacinth: A Threat to Water Bodies

by:Jinwantong     2020-08-29
Water hyacinth is not a new term in the present context. At present seven species are known all of which are placed in the genus Eichhornia. Water hyacinth are free floating, perennial and aquatic plants. It is believed that they are native to tropical and subtropical South America. The leaves are ovate, broad and glossy. These plants are known to rise above the water surface to a height of about 1 meter. Leaves measure 10-20 cm across and are float above the water surface. The leaves are characterized by long, spongy and bulbous stalks. The roots are purple-black, feathery and freely hanging. An erect stalk supports a single spike of 8-15 attractive flowers mostly pink to lavender coloured with six petals. When the plant is not blooming it is often confused with the frog's bit.
It is one of the fastest growing plants known. It mainly reproduces by the way of runners or stolons which ultimately give rise to daughter plants. The plant is also known to produce seeds that can remain viable for up to thirty years. The plant grows very rapidly and is known to double its population in about two weeks. Sometimes they also confuse many people as they resemble plants growing in the fields. They have been widely introduced throughout North America, Asia, Australia and Africa. They can be found in large water areas like in the Kerala Backwaters in India. In many areas particularly the E. crassipess is an important pernicious invasive species. They were first introduced to North America in 1884 and according to an estimate 50 kilograms per square meter of water hyacinth choked the waterways in Florida and the problem is still prevailing. When left uncontrolled water hyacinth covers all the lakes and ponds and ultimately it impacts water flow, blocks sunlight from reaching native aquatic plants, and starves the water of oxygen, often killing fish. These plants also make a space for mosquitoes, the classic vectors of disease, and a species of snail known to host a parasitic flatworm which causes schistosomiasis.
Water hyacinth is also known to affect the water bodies used by human for carrying out their normal activities. Studies have suggested that they can be used as cattle feed as well as for biogas production. Recently they are being employed in waste water treatment as well as in checking levels of pollution. The parts of plant are also used in production of traditional handicrafts in Southeast Asia. In Bangladesh farmers have started producing a fertilizer by using water hyacinths. As chemical and mechanical practices used to remove these plants from water bodies is very expensive and ineffective researchers have started using biocontrol agents against them. This practice started in 1970s when USDA researchers released three species of weevil to feed on water hyacinth into the United States. Although the success rate is slow but these weevils have been released in 20 different countries.
This plant has high nitrogen content so it can be used as a substrate for biogas production. It can easily accumulate toxins so the plant is prone to get contaminated when used as feed. Water hyacinth is also able to tolerate high levels of heavy metals like Cd, Cr, Co, Ni, Pb and Hg so it can be used for biocleaning of industrial wastewater. Eichhornia crassipes can also remove other toxins, such as cyanide, which is environmentally beneficial in areas that have endured gold mining operations.
Custom message
Chat Online 编辑模式下无法使用
Chat Online inputting...