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From Egypt to Syria, ‘water cancer’ chokes waterways

A middle-aged man in a dark gray shirt lifts an armload of water hyacinth. Image by Abd Almajed Alkarh for Mongabay.

A Syrian farmer uproots water hyacinths from the Orontes River in April 2024. Image by Abd Almajed Alkarh for Mongabay.

  • Water hyacinth, an invasive species from the Amazon, is a major threat to freshwater life and livelihoods in Syria’s Orontes River and in Egypt’s Nile Delta.
  • The plant grows and spreads quickly, outcompeting other species for space, oxygen, nutrients and sunlight.
  • Along the Orontes, in a region controlled by opposition groups, farmers and fishers have little recourse for tackling the invasive species.
  • In the Nile Delta, communities have more experience battling the plant and state-led dredging campaigns help clear water hyacinths every year, but they remain hard to control.

AL-LANI, Syria and KAFR-EL-SHEIKH, Egypt — On the banks of Syria’s Orontes River, a beautiful flower has become a nightmare. Each spring, it creeps out of the soft mud that sheltered its seeds in winter, quickly overtaking the banks. In a matter of days, the plants sprawl across the shallowest parts of the river. Their intertwined stems form tightly woven mats of waxy green leaves topped by mauve flowers that float on the river’s surface, so fishermen can’t reach the water to cast their nets.

“It grows incredibly fast, spreading by more than a meter [3 feet] every day,” says Abbas Abbas, a fisherman from the village of Al-Lani in northern Syria, standing on the edge of what was once a flowing river. “The plant starts growing from the banks and within three days, it spreads 5 meters [16 ft] into the river, completely covering its surface until July or August.”

Locals call the plant ward el-Nil, meaning “Nile rose” or “Nile flower” in Arabic, or by its local nickname: “water cancer” — a plague nearly impossible to eradicate. In English, Pontederia crassipes is known as the water hyacinth. It is considered one of the worst invasive aquatic plants in the world, able to double in size in as little as six days under the right conditions.

Lost livelihoods

On the outskirts of Al-Lani, Mohammed Bahjat Bakro gestures toward lifeless trunks in his orchard, which once produced cherries, peaches, pomegranates and walnuts. “I used to have about 150 trees, of which only about 40 remain,” he tells Mongabay. “When the Orontes River flooded my land last winter after heavy rains, it carried with it this plant that covered the soil completely, depriving it of sunlight.”

Before hyacinths invaded the orchard, Bakro grew beans and lettuce, or tomatoes and cucumbers under his trees, depending on the season. Now he pulls one handful of hyacinth after the other out of the soil, but it’s a losing battle. Water hyacinths thrive in warm, shallow, nutrient-rich water, and they’ve taken permanent hold in the village’s agricultural canals, sprawling through the summer growing season in water enriched by fertilizer runoff.

Glossy green leaves and pale mauve flowers of water hyacinth. Image by Abd Almajed Alkarh for Mongabay.
Water hyacinths growing in a field. Image by Abd Almajed Alkarh for Mongabay.
Overhead shot of a farmer bent over in a field filled with dark green water hyacinth. Image by Abd Almajed Alkarh for Mongabay.
Mohammed Bahjat Bakro clears water hyacinth from his orchard. Image by Abd Almajed Alkarh for Mongabay.

“It’s very difficult to water my crop now because of all the weeds in the river,” Arkan Sattouf, a suntanned farmer who lost 50 of his fruit trees over the past two years, tells Mongabay. “Every day, I have to clear out 1 square meter [11 square feet] of the plant just to be able to water my land.”

Since they have no natural predators outside their native range, water hyacinths spread uncontrollably once they enter a suitable waterway, outcompeting other species for space, oxygen, nutrients and sunlight. The dense mats they form over the river mean local fishermen have lost access to the water — and to part of their livelihoods.

“In this area, we can only fish onshore, because the Orontes River marks the border with Turkey. We cannot use boats to go down the river or cross to the Turkish side,” says Abbas, the fisherman. But the presence of water hyacinths means it’s now impossible to cast a net in the summer months, at the peak of the plant’s growth. For many farmers in the area, fishing is an important additional source of income, but as Abbas tells Mongabay, “There is nowhere left to even throw a hook.”

Some fishermen still try to fish by clearing small holes in the mats to reach the water, he says, but it’s a half-day of work, and the plant starts to grow back the next day. “Most fishermen got tired of doing this and abandoned fishing.”

In addition to clogging the river, the mats block the sun’s rays and reduce oxygen levels in the water, impacting phytoplankton activity. This has effects along the entire food chain, harming native fish populations and the birds that feed on them.

In Al-Lani, fishermen say that once-common species of fish have deserted the river. Fishermen told Mongabay they used to catch 5-10 kilograms (11-22 pounds) of fish on a good day, including carps, bleaks, eels, catfish and binni, a farmed species that originates from the Euphrates and Tigris basins. But their daily catch dropped to 3-4 kg (7-9 lbs) at most, with fishers reporting that some species, including catfish, carp and tilapia, are seldom seen anymore.

This decline may also be affecting endemic species in the Orontes, such as Lortet’s barbet (Luciobarbus lorteti), which has died out elsewhere and is now found only in the lower reaches of the Orontes River. Other fish species at risk are the Orontes bleak (Alburnus orontis), categorized as vulnerable on the IUCN Red List, the endangered Levantine Orontes nase (Chondrostoma kinzelbachi) and the critically endangered Orontes bream (Acanthobrama centisquama).

A solitary figure with a fishing rod on the banks of a river, water hyacinth crowds the foreground, a concrete wall on the far shore beneath a cloudless blue sky. Image by Abd Almajed Alkarh for Mongabay.
Abbas Abbas fishes in the Orontes River in April 2024, the beginning of the water hyacinth’s growing season. Across the river stands the border wall with Turkey. Image by Abd Almajed Alkarh for Mongabay.

“The number of species I catch decreased, and even the size and weight of the fish changed,” says Ibrahim al-Aswad, another resident of Al-Lani. “I also noticed that some of the grasses that used to grow on the banks of the Orontes River are disappearing because [water hyacinths] are drawing water and taking up space in the soil around the river. Even the grass our livestock used to feed on near the river in summer is disappearing.”

‘Water cancer’

Native to the Amazon, water hyacinths have long been a major threat to river ecosystems in the Middle East and North Africa, starting in Egypt, where they were first introduced in the 1880s as ornamental plants. There, they earned their Arabic name, ward el-Nil. They quickly spread to the country’s agricultural and drainage canals, where they found shallow waters suitable for their growth. But the beautiful plants are voracious water consumers.

A pale blue boat tied to a rough pole rising from gray water beneath a gray sky; mats of water hyacinth float in the lake beyond. Image by Lyse Mauvais for Mongabay.
Water hyacinth mats float in Lake Burullus, at the mouth of the Nile Delta. Image by Lyse Mauvais for Mongabay.

“Water hyacinth accelerates evapotranspiration and loss of water, with estimates varying from 2.7-fold to 3.2-fold greater in a water hyacinth mat in contrast to open water,” Ebrahem Eid, a professor at Kafr-el-Sheikh University in Egypt and author of several studies on the proliferation of water hyacinths in the Nile Delta, told Mongabay. In Egypt, the plant causes the loss of around 3.5 billion cubic meters (925 billion gallons) of water each year through evapotranspiration — roughly 4% of the country’s annual share of the Nile waters. Wherever they multiply, water hyacinths can cause localized water shortages, responsible for the loss of thousands of acres of farmable land.

They also impact biodiversity. Egypt’s Nile Delta contains several wetlands of high ecological importance, including Lake Burullus, which was designated a Ramsar site in 1988 due to its importance for migratory birds. Each year, an estimated half a million waterbirds winter in Lake Burullus and adjacent marshes. The area is home to six subspecies of birds that are endemic to Egypt and to one of the world’s largest known concentrations of ferruginous duck (Aythya nyroca), a near-threatened species.

The lake also supports a large fishing industry centered on tilapia, catfish, mullet, eel and shrimp. But over the past two decades, the proportion of higher-value marine species like mullet and shrimp decreased from fishermen’s catch (to the benefit of tilapia), and several species disappeared altogether due to significant changes in the lake’s ecosystem.

Water hyacinths have played a role in this transformation. Lake Burullus is a brackish lagoon that receives freshwater from the Nile at its southern end, and seawater through an inlet connecting it with the Mediterranean Sea to the north. But starting in the 1990s, Burullus began receiving increased flows of nutrient-rich agricultural runoff while seawater inflow decreased, altering salinity levels in the lake.

This created ideal conditions for the spread of aquatic plants, including water hyacinths, which proliferated on the southern shores of the lagoon. Although the main threat to the Burullus ecosystem is the influx of polluted runoff, the associated spread of aquatic plants is a major issue for fishermen, who are losing access to fishing areas due to increasing vegetation. A 2013 study by the Centre for Development Innovation at Wageningen University & Research in the Netherlands specifically flagged P. crassipes as a matter of concern due to its adverse impact on open water in the lake.

In Syria, as in Egypt, water hyacinths add significant pressure to already strained water resources and disrupt freshwater ecosystems. “One plant of ward el-Nil absorbs 7 liters [1.8 gal] of water per day, and there are thousands of this plant along the Orontes, consuming the water of government-run irrigation projects,” Mohammed Nehme Amhan, a local official with the opposition-run water resources ministry, told Mongabay. “It also blocks sunlight reaching organisms in the river and decreases oxygen levels in the water, causing obvious harm to fish.”

According to a report by Syria’s General Commission for Agricultural Research (GCAR), P. crassipes has been present in the country since the early 2000s at least, mostly contained to the 570-kilometer (350-mile) Orontes River and Al-Kabir River, at the border with Lebanon. Farmers in Al-Lani noticed it more than 10 years ago, but it wasn’t a major issue then because heavy rain every winter washed the plants away before they could clog the river.

But in the spring of 2023, water hyacinths started spreading dramatically in the aftermath of the double earthquake that devastated Turkey and Syria on Feb. 6 that year and killed more than 60,000 people. The earthquakes also destroyed mud embankments built by farmers along the Orontes River, causing localized floods that lasted for several months.

“Instead of being washed away by the river like in previous winters, the plant encroached on flooded farmland,” al-Aswad says. “The soil remained soaked for weeks, which stunted the development of fruit trees.” Dozens of his trees, including cherry, mango, peach and plum trees the area was famous for, died, while water hyacinths spread uncontrollably across the flooded orchards.

A man uses a pitchfork to vigorously lift a tangle of glossy, green water hyacinth. Image by Abd Almajed Alkarh for Mongabay.
Arkan Sattouf removes water hyacinths from the Orontes River. Image by Abd Almajed Alkarh for Mongabay.

Impossible to control

Water hyacinths are practically impossible to remove once they’ve settled somewhere. The plant can spread both sexually (through seeds) and asexually, growing out of the broken stems of other plants. Since its seeds can remain in the soil for 20 years and germinate again in moist soil or shallow waters, it’s a ticking time bomb.

In Al-Lani, residents first tried to spray the plant with various pesticides. But these attempts, which risk polluting the water and harming native species, proved useless. “It only affected the leaves at the surface of the water,” Sattouf says. “After 20 days, the plants resurfaced because its root and bulbs had not been affected.”

The most effective way to remove it is to pull it out, by hand or with machines, but that’s a tedious job that requires weeks of sustained effort. “The plants grow so densely together that you need to use a car to pull out 1 meter of it,” Bakro says. “And it grows so fast that it reaches its maximum height, about 1 meter, in only 48 hours.” It’s a Sisyphean task.

“If I remove it only from my land, it will grow back on my land from my neighbor’s land,” al-Aswad says with a sigh. “And if we remove it in our village, it will grow back from the neighboring village.”

In Egypt’s Nile Delta, farmers and authorities face the same challenges. Every year, dredging campaigns are launched to remove the plant, but water hyacinths are still colonizing thousands of drainage and irrigation canals. When Mongabay visited the countryside of Kafr-el-Sheikh, south of Lake Burullus, in March 2024, dredgers were at work in some of the larger canals, pulling out batches of aquatic plants dripping with fresh mud as they do every year. Cattle egrets hung like heavy white fruits above newly dredged canals, lined by heaps of cracked mud.

Open water gives way to a mat of green beyond a pair of backhoes, either side of a canal, dredging hyacinth.
Water hyacinths and siltation mean canals like this one in a 2013 photo from the Central Nile Delta must be dredged every year. Image by François Molle/Water Alternatives via Flickr (CC BY 2.0)
An irrigation canal clogged by water hyacinths in the Nile Delta, Egypt. Image by Lyse Mauvais for Mongabay.
An irrigation canal clogged by water hyacinths in the Nile Delta, Egypt. Image by Lyse Mauvais for Mongabay.

But many of the smaller channels of irrigation networks that spread out into the fields were still clogged with water hyacinths and plastic waste caught in the floating mats. In many places, the water was no longer visible, drowned beneath a sea of green leaves.

“When the water level drops in our irrigation canal, I call the agricultural cooperative to dredge it,” Sayyed, an Egyptian rice farmer, tells Mongabay near a canal filled to the rim with water hyacinths. “They charge me 6 Egyptian pounds [about 13 U.S. cents] per meter of canal. In winter I don’t call them because I don’t need water, but in summer we need to dredge often to ensure the rice gets irrigated.”

Because mechanical removal requires constant work, Egyptian scientists have also tried to develop biological control methods. In the early 2000s, after cautiously checking there wouldn’t be a threat to native plants, researchers successfully introduced two species of Latin American weevils that feed on water hyacinths in two Egyptian lakes. The weevils reduced the presence of water hyacinths by 90% on one of these lakes. But although these efforts helped control the plant, they didn’t eradicate it. Biological control methods sometimes fail if the weevils don’t thrive in their new environment, and water hyacinths can continue to spread.

These initiatives are also expensive and aren’t replicable everywhere. For the farmers in Al-Lani, who live in a conflict zone controlled by opposition groups at war with the government since 2011, these solutions are out of reach.

Agricultural institutions have largely broken down and local authorities don’t have the means or equipment to dredge irrigation canals. That leaves farmers on their own to battle the plant. To get around the lack of machinery, some have even designed their own small-scale dredging machines.

Meanwhile, regional cooperation efforts to promote biocontrol methods don’t reach all areas affected by water hyacinths. While government-controlled parts of Syria sometimes benefit from trainings and exchanges of expertise with neighboring countries, opposition-controlled regions don’t. In 2019, the U.N.’s Food and Agriculture Organization (FAO) organized a workshop for Syrian and Lebanese officials to share Egypt’s experience with biological methods.

But the training only included Damascus-based government experts, leaving out those from areas controlled by Syrian opposition groups. And since biological control methods require significant know-how (importing the weevils from abroad, quarantining them after arrival, and reproducing them in a controlled environment before releasing them), they’re unlikely to take root in places like Al-Lani without government support.

The good news is that with the right resources, water hyacinths can become useful to farmers in Syria and elsewhere in the region. Different options to turn the weeds into productive assets have been tested successfully: in Nigeria, its leaves are used as additives in livestock feed. In Egypt, a startup made fish feed from its leaves, extracted collagen from its stems, and sold it to local factories for paper production. Some communities also use the stems to craft baskets and furniture, and scientists have also used its high absorption properties to remediate sites contaminated by heavy metals and to treat wastewater.

But these labor-intensive projects can only work with sustained buy-in from local communities, which is often lacking. Could a place like Al-Lani, whose residents have learned to rely on no one but themselves after 12 years of war, be just the sort of environment where innovative solutions take root?

Turning Kenya’s problematic invasive plants into useful bioenergy

Citations:

Harun, I., Pushiri, H., Amirul-Aiman, A. J., & Zulkeflee, Z. (2021). Invasive water hyacinth: Ecology, impacts and prospects for the rural economy. Plants, 10(8), 1613. doi:10.3390/plants10081613

Eid, E. M., & Shaltout, K. H. (2017). Population dynamics of Eichhornia crassipes (C. Mart.) Solms in the Nile Delta, Egypt. Plant Species Biology, 32(4), 279-291. doi:10.1111/1442-1984.12154

Ghoussein, Y., Abou Hamdan, H., Fadel, A., Coudreuse, J., Nicolas, H., Faour, G., & Haury, J. (2023). Biology and ecology of Pontederia crassipes in a Mediterranean river in Lebanon. Aquatic Botany, 188, 103681. doi:10.1016/j.aquabot.2023.103681

Fayad, Y. H., Ibrahim, A. A., El-Zoghby, A. A., & Shalaby, F. F. (2000). Ongoing activities in the biological control of water hyacinth in Egypt. In ACIAR Proceedings (pp. 43-46). ACIAR. Retrieved from http://www.bio-nica.info/biblioteca/Fayad2001Eischhornia.pdf

Shabana, Y. M., Elwakil, M. A., & Charudattan, R. (2000). Biological control of water hyacinth by a mycoherbicide in Egypt. In ACIAR Proceedings (pp. 53-56). ACIAR. Retrieved from http://www.bio-nica.info/Biblioteca/Shabana2001Eischhornia.pdf

Banner image: A Syrian farmer uproots water hyacinths from the Orontes River in April 2024. Image by Abd Almajed Alkarh for Mongabay.

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