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| Site of the dried Kara River |
Unidentified green plants are seen on the river while the water body has given way. The Kara cattle market community under the bridge along the Lagos-Ibadan expressway has become a Mecca of some sort with residents of the community and passers-by trooping to see the dried section of the river which once provided water for the Kara cattle and ram market. Before the unusual incident, the water body once served as means of transportation for canoe owners but residents say they woke up to see the channel blocked on Saturday morning. Surprisingly, on the other side of the Kara Bridge, the river was seen flowing freely.
Environmentalists have however warned that residents keep off the blocked channel for the risks of it opening up unexpectedly and advised relevant authorities to find a means of clearing the plants.
THE HYACINTH PLANT (Suspected Culprit)
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| Hyacinth Plant |
Water hyacinth is one of the world’s worst aquatic weeds. It harass rivers, dams, lakes and irrigation channels on every continent except Antarctica. It devastates aquatic environments and costs billions of dollars every year in control costs and economic losses. Water hyacinth is native to the Amazon basin in South America and was brought to Australia in the 1890s as an ornamental plant. The first record of water hyacinth in New South Wales (NSW) was in 1895.
In 1897, the government botanist Mr J. H. Maiden noted that it had spread rapidly in the ponds in the Royal Botanic Gardens in Sydney. At that time, he warned that the plant should be kept away from the northern rivers where it ‘may very rapidly become a serious pest’. Unfortunately, this warning went unheeded and by the early 1900s it had spread along the east coast of Queensland and the north-eastern regions of NSW. Water hyacinth is justifiably called the world’s worst aquatic weed due to its ability to rapidly cover whole waterways.
Water hyacinth (Eichhornia crassipes (Mart) Solms is a troublesome aquatic weed and has spread in almost all lakes, ponds and rivers not only in our country but in the entire tropical world. Therefore attention has been focused on its environmental impact since its luxuriant growth in the water bodies interferes in the activities of mankind, which has caused great concern. Its wide spread occurrence in the fresh water lakes and riverbeds is proving detrimental to fishing, rowing, and depleting water content from the water bodies and interfering in water utilization and other activities. In view of the alarming situation, it was decided to control the weed growth by utilizing the Biocontrol methods to control the water hyacinth menace.
Water hyacinth by its abundance of leaves, dense vegetation and innumerable rootlets in tertiary manner obstruct water flow in irrigation channels, hydroelectric power generation, interfere with navigation, hinders flow of water and displaces many aquatic grasses which were useful as fodder for cattle and also suppresses the phytoplankton growth.
IT forms dense, impenetrable mats over the water surface. Specific impacts include:
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| Hyacinth plant forms an impenetrable mats |
1. blocking irrigation channels and rivers
2. restricting livestock access to water
3. destroying natural wetlands
4. eliminating native aquatic plants
5. reducing infiltration of sunlight
6. changing the temperature, pH and oxygen levels of water
7. reducing gas exchange at the water surface
8. increasing water loss through transpiration (greater than evaporation from an open water body)
9. altering the habitats of aquatic organisms
10.restricting recreational use of waterways
11.reducing aesthetic values of waterways
12.reducing water quality from decomposing plants
13.destroying fences, roads and other infrastructure when large floating rafts become mobile during flood events, and
14.destroying pastures and crops when large floating rafts settle over paddocks after flood events.
WATER HYACINTH GROWTH
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| Water Hyacinth Growing |
Water hyacinth will rapidly take over an entire waterway. Under favorable conditions it can double its mass every 5 days, forming new plants on the ends of stolons. It also grows from seed which can remain viable for 20 years or longer. This enormous reproductive capacity causes annual reinfestation from seed and rapid coverage of previously treated areas, making ongoing control necessary.
HUMAN ROLE IN THE GROWTH OF WATER HYACINTH
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| Hyacinth Plant |
An ecosystem’s biological community consists of populations of every species of plant, animal and microorganism in the ecosystem. People interact directly or indirectly with populations whenever they interact with ecosystems. Water hyacinth is a floating plant that has spread from South America to waterways around the world. It can cover the water so completely that it obstructs the movement of boats. Imagine a lake that is 10 kilometres in diameter. It takes eight billion hyacinth plants to cover a lake of this size completely.
To start with, our lake has no water hyacinth. Then we introduce one hyacinth plant onto the lake. After one month, this plant forms two plants. After another month the two plants have multiplied to four and the doubling continues month after month. Two years pass, and the hyacinths have multiplied to 17 million plants. Nobody pays attention to them because 17 million plants cover only 0.2 per cent of the lake. Six months later, 30 months after we put the single plant on the lake, there are one billion hyacinth plants, which cover about 13 per cent of the lake Now people notice the hyacinths. Although there are not enough hyacinth plants to be a problem for the movement of boats, some people are worried. Other people say, ‘Don’t worry. It took a long time to get this many hyacinths. It will be a long time before there are enough to cause a problem.' Which people are right? Is the problem a long time in the future, or will there be a problem soon? In fact, with hyacinth doubling every month, the lake will be completely covered after only three more months.
This is a true story. Water hyacinth has become an uncontrollable nuisance in many places, including the world’s second largest lake, Lake Victoria in East Africa, where fish from the lake are a major source of animal protein for millions of people. Parts of Lake Victoria are now so badly clogged with water hyacinth that fishing boats cannot move through the water. Thousands of fishermen are out of work, and the supply of fish has declined drastically.
