An aquatic weed harvester, also known as a water mower, [1] [2] mowing boat and weed cutting boat, [3] is an aquatic machine specifically designed for inland watercourse management to cut and harvest underwater weeds, reeds and other aquatic plant life. [4] The action of removing aquatic plant life in such a manner has been referred to as "aquatic harvesting". [5]
Water is an important resource and in many countries, waterways are increasingly clogged by aquatic plant growth. This is particularly so in tropical countries where warmer water means the plants grow more quickly, and increasing run-off of fertilisers and effluent has exacerbated the problem. Irrigation ditches and pumps can become overgrown with vegetation, power station and factory water intakes can get blocked, boats can get hindered, fish stocks can be disrupted, and water moves more slowly, resulting in greater evapotranspiration and a greater risk of flooding. In some large irrigation projects in India, canals have become so overgrown with vegetation that water flow has been reduced to a fifth of its previous amount. In Bangladesh, floodwater has washed mats of water hyacinth onto paddy fields, overwhelming the emerging rice crops. [6] Small fish can become entangled in excessive algal growth. [5]
Rice is the main aquatic plant grown for human food, but smaller areas of watercress and water chestnut are also cultivated. In their native environments, aquatic weeds are part of a balanced ecosystem, and it is mainly introduced species of water plant that become invasive and cause problems by congesting water bodies. The worst culprits, found in both temperate and tropical waterways, are floating plants such as water hyacinth, water lettuce and Salvinia , fully submerged rooting plants such as Hydrilla and water milfoil and rooting plants that reach the surface such as cattail, papyrus, bulrush and reed. [6]
Weed cutting boats are developed to enable the maintenance of canals, lakes and rivers [4] and to remove excessive aquatic life such as algae and other plants that may negatively affect a waterway's ecology. Mechanical harvesters are large floating machines that have underwater cutting blades that sever the stems of underwater plants, gather the weeds and raise them on conveyor belts, storing the vegetation on board in a hold. Periodically this is discharged to a barge or an onshore facility. The harvested product can be composted, sent to a landfill site or used in land reclamation. [7] In developing countries aquatic vegetation may be harvested by hand or by net from the shore, cut and harvested by boat and lifted ashore by hand, crane, pump or conveyor system. The harvested vegetation may be used for the feeding of livestock. To reduce the high moisture content and to make it easier to transport, the weed can be chopped and pressed. [8] Other uses to which the harvested vegetation can be put include ensiling the material for livestock fodder, adding it to the soil as a bulky organic fertilizer, manufacturing the raw material into pulp, paper or fibre, and fermenting it to produce methane for energy production. [6]
Mechanical weed harvesters are effective at clearing aquatic weeds and the machines provide immediate relief from nuisance vegetation that interfere with navigation and recreation. Aquatic plants contain nitrogen, phosphorus and potassium that is bound in the vegetation, by removing the plants the nutrients are also removed. Removal of the biomass (plant material) prevents the build-up of muck and sediment on the bottom of the lake that occurs from the rotting weeds. Mechanical harvesters can also be used to improve the fishery by leaving behind aquatic vegetation for food and habitat. Aquatic weed machines are expensive and does require a capital investment and the process may need to be repeated several times in a growing season. Small fragments of weed may remain in the water and may spread to other locations thereby aiding in the dispersal of invasive species. However, a recent study by the Chautauqua Lake Association found that the harvesters left less than 1% of the loose plants behind. Some areas may be too shallow for the mechanical harvester and it may be unable to access restricted locations. [7] Submerged tree stumps can damage the machine. [5] Aquatic weeds can also be utilized as a source of biofuel. [9]
An alternative to mechanical harvesting is the use of herbicides, which are easy to apply and less expensive, but may have unwanted adverse impacts on the environment. [10] While many aquatic herbicides have received EPA approval and are considered safe for aquatic environments, long-term studies have found that aquatic herbicides can have major impacts on fish reproduction. Researchers at the University of Wisconsin-Madison found that fathead minnows exposed to concentrations of fluridone showed signs of endocrine disruption. [11]
In June 2015 in Uganda, use of the aquatic weed harvester was recommended by the country's Ministry of Agriculture to reduce water hyacinth growth in Lake Victoria, which has caused a scarcity of fish in the lake. [12] The scarcity of fish has negatively-affected the livelihood of locals who live in the lake's region. [12] Additional types of machines were recommended to address the problem, which were the hydraulic harvester, take out elevator and dredger. [12]
In August 2015 in Hyderabad, India, an aquatic weed harvester was used to remove algal weeds and trash from Hussainsagar Lake. [13] An amphibious hydraulic excavator was also used. [13] The work was performed to address pollution problems at the lake, which had accumulated significant algae and rubbish such as plastic bags and plastic waste, food wrappers, and various garbage, some of which was floating atop the lake. [13]
Some U.S. companies manufacture aquatic weed harvesters. [4] One such machine manufactured by a U.S. company can cut around one-half an acre of weeds a day, and costs over $100,000. [4]
Tampa, Florida used an aquatic weed harvester in 2013 to clear aquatic plant life from lakes in the area. [4]
In 2012 in Leoni, Michigan, an aquatic weed harvester was used to remove algae from Center Lake. [5] The algae appeared to have roots, and other techniques such as attempting to kill it with chemicals were unsuccessful. [5] The machine used collects algae and weeds that live at the bottom of the lake, removing them from the waterway. [5]
Salvinia molesta, commonly known as giant salvinia, or as kariba weed after it infested a large portion of Lake Kariba between Zimbabwe and Zambia, is an aquatic fern, native to south-eastern Brazil. It is a free-floating plant that does not attach to the soil, but instead remains buoyant on the surface of a body of water. The fronds are 0.5–4 cm long and broad, with a bristly surface caused by the hair-like strands that join at the end to form eggbeater shapes. They are used to provide a waterproof covering. These fronds are produced in pairs also with a third modified root-like frond that hangs in the water. It has been accidentally introduced or escaped to countless lakes throughout the United States, including Caddo Lake in Texas, where the invasive species has done extensive damage, killing off other life.
Weed control is a type of pest control, which attempts to stop or reduce growth of weeds, especially noxious weeds, with the aim of reducing their competition with desired flora and fauna including domesticated plants and livestock, and in natural settings preventing non native species competing with native species.
Water garden or aquatic garden, is a term sometimes used for gardens, or parts of gardens, where any type of water feature is a principal or dominant element. The primary focus is on plants, but they will sometimes also house waterfowl, or ornamental fish, in which case it may be called a fish pond. They vary enormously in size and style.
Triclopyr is an organic compound in the pyridine group that is used as a systemic foliar herbicide and fungicide.
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.
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.
Myriophyllum is a genus of about 69 species of freshwater aquatic plants, with a cosmopolitan distribution. The center of diversity for Myriophyllum is Australia with 43 recognized species.
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.
Crystal River is a very short river in Citrus County, Florida, flowing into the Gulf of Mexico. It is just seven miles long, and has a drainage basin of five square miles, joining Kings Bay to the Gulf of Mexico. The river's significance is in the thirty natural springs that add an average of 300 million gallons of warm water to the river every day. These springs include Three Sisters Springs.
Pontederia crassipes, commonly known as common water hyacinth, is an aquatic plant native to South America, naturalized throughout the world, and often invasive outside its native range. It is the sole species of the subgenus Oshunae within the genus Pontederia. Anecdotally, it is known as the "terror of Bengal" due to its invasive growth tendencies.
Lake Oscawana is a lake at the heart of Putnam Valley, New York. United States.
Glenbrook Lagoon is a fresh water lagoon located in Glenbrook, New South Wales at the foot of the Blue Mountains. It is heritage-listed.
Pontederia azurea is a water hyacinth from the Americas, sometimes known as anchored water hyacinth. It is the type species of Pontederia subg. Eichhornia, which was previously recognized as part of the polyphyletic genus Eichhornia. It is of some interest as an aquarium plant.
Water hyacinth has become a major invasive plant species in Lake Victoria and while it is native to the continent of South America, human activity has introduced the greenery to Lake Victoria, where it is claimed to have negatively affected local ecosystems.
Mechanical weed control is a physical activity that inhibits unwanted plant growth. Mechanical, or manual, weed control techniques manage weed populations through physical methods that remove, injure, kill, or make the growing conditions unfavorable. Some of these methods cause direct damage to the weeds through complete removal or causing a lethal injury. Other techniques may alter the growing environment by eliminating light, increasing the temperature of the soil, or depriving the plant of carbon dioxide or oxygen. Mechanical control techniques can be either selective or non-selective. A selective method has very little impact on non-target plants where as a non-selective method affects the entire area that is being treated. If mechanical control methods are applied at the optimal time and intensity, some weed species may be controlled or even eradicated.
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.
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.
The Berky GmbH is a German company that manufactures machines, specialized vehicles and boats for water maintenance. The company is based in Haren (Ems) in the Emsland region.
