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> Invasive plants in Israel > Eichhornia crassipes (Mart.) Solms

Eichhornia crassipes (Mart.) Solms
Life form: Perennial aquatic
En: Water hyacinth. Fr: Jacinthe d'eau
Provenance: Tropical southern America

Distribution in Israel
Two large and developing populations of Eichhornia crassipes have been recorded in Israel since 2004: The first is found in a pond of about 1 Ha nearby Tel-Itshak, and a second population has developed since 2005 in the Alexander river, northeast to the city of Netanya. A third emerging population was found in March 2006 in the Na'aman river, east to the city of Akko (Western Galilee).

Proliferation status
The water hyacinth in Israel is an 'invasive' alien according to the terminology suggested by Richardson et al. (2000). According to the Invasive Species Speciality Group (ISSG) of the World Conservation Union (IUCN) (Lowe et al. 2000), this plant species is one of the '100 of the World's Worst Invasive Alien Species'.

Eichhornia crassipes in Israel
The earliest evidence of natural area invasion by the water hyacinth in Israel is dated to the 1950s when Eichhornia crassipes infested the Yarkon river near Tel-Aviv.
The species has been introduced in Israel presumably for ornamental purposes. The possibility that the water hyacinth has been very recently used in order to cleanse water in aquaculture facilities near the Alexander river is under investigation.
Though the water hyacinth invaded waterways 55 years ago in Israel, its resurgence in natural areas seems very recent as it remained unnoticed until 2004.
The water hyacinth rapidly forms dense mats on the water surface that crowd out native species. Simultaneously, it modifies water temperatures and significantly decreases water oxygenation. As a consequence the biological richness in infested aquatic ecosystems drops dramatically.
No control programs have been yet developed in Israel in order to eradicate the two populations that have been recently localized. However the Ministry of Environment and the Nature and Parks Authority have been informed and are aware of the threat posed by the water hyacinth.
Indeed, the very high proliferation rate of the water hyacinth, coupled with its formidable ability to literally transform the physical conditions of aquatic ecosystems makes this invasive one of the most dangerous plant pests in Israel. Should the water hyacinth continue to proliferate and reach the Hule region, where vast natural swamps harbor thousands of migratory birds each year, we will face a major ecological disturbance that may lead to the collapse of this entire and unique ecosystem recently restored through tremendous efforts.
A further problem with Eichhornia crassipes in natural areas in Israel is that winter temperatures, at least in the coastal plain, do not harm the populations.

The water hyacinth invading the Alexander River in the Sharon plain (Sept. 11th, 2005)

Mechanical removal can be performed with harvester machines. Chemical control can be done with the glyphosate formulation registered for aquatic use. Biological control experiments have proved effective, particularly with Neochetina species

A pond, south to the city of Netanya, completely covered by Eichhornia crassipes (May 26th, 2005)

Guillarmod A.J. (1979) Water weeds in southern Africa. Aquatic Botany 6:377-391

Last Modified: 18th May 2006

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