How can something so beautiful be such a menace? The prolific water hyacinth (Eichhornia Crassipes) has been a global problem for decades and is often referred to as the “world’s worst aquatic weed,” “blue devil,” or “Superpest.”
Left in its natural habitat, the rivers of South America, the growth of the water hyacinth is kept in check by annual floods. The torrents of water sweep much of the waterweed out to sea into salt water where it cannot survive. However, in the 1800s, due to its exotic beauty the water hyacinth was introduced to other countries, including the United States, as an ornamental plant for ponds. The attractive floating plant with its lovely lilac-mauve flowers also proved to be useful as a water purifier because its roots feed off the toxins in fresh water systems.
The hyacinth reproduces itself primarily through clonal propagation (identical genetic copies) via its stolons; stems which form new plants at their tips. Stolons are fragile, break easily, and are carried off to new locations. The water hyacinth blooms last only for a day before they release numerous small seeds, some to germinate, and others to remain dormant for up to 15 years. An area can dry up and the plants disappear, but once the rains come, seeds germinate. In one growing season, 25 plants can generate two million offspring. Under favorable growing conditions, the plants can double its mass every five days.
Due to wind and water currents, hyacinths tend to accumulate against riverbanks and in sheltered bays of lakes, often in mats so dense that people can walk on them. The results can be catastrophic; irrigation channels are fouled, freight ships and fishing boats are hindered, the quality of drinking water is affected, and fish stocks are reduced.
This giant of germination infests rivers, dams, lakes, and channels on every continent and costs billions each year in control expenditures and economic losses. Fifty two (52) countries of the world in tropic and sub-tropic regions, including the United States, are affected by the weed’s uncontrolled overgrowth in fresh waterways.
The key to the problem is control, and one of the means is water management. Heavy nutrient loadings in water from the erosion of cultivated land, cattle yards, domestic and municipal sewage outfalls and wastewater discharges from factories all promote rapid growth of the hyacinth. Conservation farming techniques and water treatment before discharge can minimize growth. Another means of control is harvesting. According to an Australian government publication, fifty million tons of water hyacinth is removed from the White Nile annually, and the Panama Canal is kept clear of the weed by mechanical harvesting.
In the United States, tens of millions of dollars have been appropriated by Congress and the affected states of California, Florida, Louisiana, Mississippi, and Texas in a futile attempt to eradicate the hyacinth. Everything from pitchforks to poisons to dynamite has been used to virtually no avail.
A problem more significant than the drain on tax dollars from the federal and state treasuries is environmental pollution created by the biological and chemical means of attempted control. Science has yet to discover an effective technical approach to successfully eliminate the water hyacinth infestation without the accompanying harmful side effects.
The attached paper explains some economic impacts.