This alien plant is lethal for the environment. Now it’s being turned into a plastic to regrow forests | CNN

1. This alien plant is lethal for the environment. Now it’s being turned into a plastic to regrow forests | CNN

Water hyacinth — These purple-blossoming plants can spread to cover every inch of a lake, blocking out sunlight and crowding out native plants. The water hyacinth most likely originated in Brazilian rainforests, and became a popular addition to garden ponds worldwide in the 1890s. But this formidable species can double its size in a fortnight. The flowers, pictured here in Dhaka, Bangladesh, are now found on every continent except Antarctica. Scroll through the gallery to see more of the planet's most problematic invasive species.

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Northern Pacific Seastar — Growing up to half a meter in width, the Northern Pacific Seastar (also known as the Japanese Starfish) has spread from the North Pacific to the south coast of Australia. A single female can carry up to 20 million eggs. It's just one of the invasive species that are traveling to new environments and harming native ecosystems.

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Warty comb jelly — The humble comb jelly has no brain, stomach or bones. It eats microscopic sea organisms, as well as fish eggs and larvae. Native to the Atlantic coasts of North and South America, warty comb jellies reached the Black Sea, Aegean Sea and Caspian Sea during the 1980s. The jellies traveled across oceans in the ballast water of ships. In these new waters, they flourish thanks to a lack of natural predators. It is associated with crashes in fish numbers. Dolphin populations, dependent on fish supplies, have plummeted in the Black and Azov Seas as a result of the jelly invasion, according to the World Wildlife Fund.

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Asian Longhorn beetle — Trees where these beetles lay their eggs are doomed to a slow death, as larvae gnaw away at their bark from the inside. Native to Asian countries including China and Japan, this species has reached Europe and North America, mostly through wooden packaging. They have already infested many poplar plantations in China, and have also been found in chestnut trees, willows and elms. The US Department of Agriculture has warned that the insects could devastate American timber industries and forests if left unchecked.

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Cane toad — These creatures are indigenous to South America. They were deliberately introduced to many countries in the 1930s (including the USA and Australia) to help control sugar cane pests, like beetles. But cane toads proved to be disastrously voracious, eating anything from honeybees to dog food. An estimated 1.5 billion cane toads live in Australia alone. When attacked or eaten, they emit venom that can be fatal to wild animals and household pets alike. Studies in Bermuda show they are outcompeting native frogs.

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Stoat — Related to weasels, polecats and ferrets, the stoat is a small but ferocious predator. Stoats have no qualms about attacking larger animals, including rabbits and chickens. European settlers took stoats to New Zealand for pest control purposes, where they wreaked havoc on native bird populations. The New Zealand Government spends millions of dollars each year protecting native birds from stoats, which feast on their chicks and eggs.

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European Starling — Sixty of these birds were set free in New York in 1890, in a bizarre plan to introduce to the USA every bird mentioned in a Shakespeare play. European Starlings were also deliberately introduced to regions of Australasia and South Africa to control native insect populations. Today, between 100 million and 200 million Common Starlings on six continents destroy many crops, and out-compete birds like woodpeckers in the United States and black cockatoos in Australia. However, their numbers appear to have fallen in recent decades, possibly due to intensive farming techniques.

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Giant African land snail — Its native range is coastal East Africa, but this snail has reached all continents except Antarctica. They are sold as food, pets, and for medicinal purposes, which led to their accidental introduction to the wild. In New Zealand, the Giant African land snail eats many types of local snails, as well as native plants.

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Red deer — This large deer species was brought from Europe and Western Asia to Australia, New Zealand and South America, for trophy hunting and livestock. It flourishes in a wide range of habitats and can outcompete native mammals searching for food.

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Common prickly pear — Originally from the Americas, this cactus is an invasive species in South Africa, Kenya and Australia. It grows in bristly thickets up to two meters high, and was often introduced to contain livestock. It is highly drought resistant and frost resistant, and can spread across millions of hectares of land. During an infamous spell dubbed "the green hell" in Australia in the 1920s, the cacti spread so rapidly and thickly across rural plains that people abandoned their homes and farms. The plants were tamed when authorities introduced a foreign cactus gourmet, the cactoblastis moth, in 1925.

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Black rat — Also known as the ship rat, it is native to India but over thousands of years, it spread to every continent except Antarctica by hiding in ships. These furry stowaways can devastate wildlife populations as they guzzle through native insects, bird eggs and chicks, and fruit.

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Big-headed ant — The big-headed ant first spread from southern Africa via ships during the 18th century. They are now found in both tropical and temperate regions, from Japan to Puerto Rico. They chew through electric wires as well as seeds, aphid honeydew, and other insects. As they graze, the ants can spread viruses among crops. Native spiders and weaver ants also struggle when this species infests new land.

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In pictures: Invasive species around the world Prev

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CNN  — 

Lake Naivasha, northwest of Nairobi, Kenya is becoming increasingly unnavigable. Water hyacinth, the world’s most widespread invasive species, is blanketing the lake, choking its fish and leaving people stranded.

“Sometimes it becomes very serious,” says Simon Macharia, a local fisherman, about theweed problem. “There was this incident where fishermen were trapped by hyacinth inside the lake for three days. We had to seek help from the government (who) used a helicopter to rescue them.”

Macharia says that some days he’s simply unable to fish on the lake because of the plant. When he does, he can lose his nets underneath the floating weed, incurring costs while preventing him from earning that day. Water hyacinths also cover the surface, cutting off sunlight, outcompeting other plant species and starving water of oxygen. That means there are fewer fish for Macharia to catch in the first place.

The problem is so vast it can be seen from space. It also threatens the cut off the flower industry in the wetlands surrounding the 150 square kilometer (58 square mile) lake.

What’s happening in Lake Naivasha is a story repeated all over the world. Water hyacinths are native to South America, but were introduced as an exotic ornamental to many other countries. They’ve since taken over freshwater environments and are labeled an alien invasive species on every other continent aside from Antarctica.

As well as their impact on biodiversity and livelihoods, the floating plant can clog hydroelectric and irrigation systems, meaning that one does not need to live in their proximity to be affected. It’s the highest-profile example of an invasive aquatic plant crisis that has cost the global economy tens of billions of dollars historically, and now more than $700 million annually.

The problem with water hyacinths is particularly acute in Africa. A 2024 report by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), a body founded by the UN Environment Programme, described the plant’s “exponential expansion,” with land use changes and climate change adding potential fuel to the fire.

Residents of Kihoto estate on the shores of Lake Naivasha, Kenya, were faced with water hyacinth at their doorsteps after extreme rainfall rose the level of the lake in October 2020.

TONY KARUMBA/AFP/AFP via Getty Images

Taskforces from multiple organizations have attempted to find solutions. Introducing weevils that attack the plant can restrict its spread and even cause it to lose buoyancy. There are also proposals to harvest the water hyacinth and combine it with municipal waste and cow dung to produce biofuel. Now a Kenyan company is addressing the problem as well as the country’s plastic pollution issueby turning the invasive plant into a bioplastic.

HyaPak Ecotech Limited, founded by Joseph Nguthiru, began life as a final year project by the former Egerton University civil and environmentalengineering student. Nguthiru and his classmates experienced the problem of water hyacinths firsthand on a field trip to Lake Naivasha in 2021, when their boat became trapped for five hours. They returned determined to do something about it.

Nguthiru’s bioplastic is made from dried water hyacinth combined with binders and additives, which is then mixed and shaped.

The product, which biodegrades over a few months, was first used as an alternative for plastic packaging. In 2017, Kenya introduced a law banning single-use plastic bags, and in 2020 all single-use plastics were banned from protected areas. The results have been mixed; with homegrown manufacturing banned, there have been reports that single-use plastic bags have been smuggled into Kenya from neighboring countries. “The problem behind (the ban) is that there were no proper alternatives that were produced,” argued Nguthiru.

His product is “killing two birds with one stone,” he believes. “Most single-use plastic products tend to have a lifespan of about 10 minutes after they come out of supermarket shelves. So why not make them biodegradable?”

A 2018 image of a fisherman struggling to navigate through the waters of Lake Victoria, another lake in Kenya afflicted with water hyacinth.

Yasuyoshi Chiba/AFP/Getty Images

HyaPak has gained widespread attention, winning the Youth category at the East Africa Climate Action Awards,a prize at UNESCO’s World Engineering Day Hackathon, and a Prototype for Humanity Award 2023 announced at the COP28 climate conference. Nguthiru was also named a 2023 Obama Foundation Africa Leader.

Fishermen including Macharia are now harvesting the invasive plant on Lake Naivasha, then drying and selling it to HyaPak. It’s a useful alternative income, he said, especially on days when the plant has covered his net, preventing it from catching fish.

Macharia said he hopes HyaPak will soon be able to scale up its activities, allowing the lake’s surrounding community to harvest greater quantities of water hyacinth. “If Joseph could get funding, I think he can buy larger quantities and at least many people will get work,” he said.

One project that could help HyaPak grow is its partnership with the Kenyan government to use its products as part of a flagship reforestation scheme.

According to Global Forest Watch, Kenya lost 14% of its tree cover between 2001 and 2023.In late 2022, Kenya’s Forestry and Land Restoration Acceleration program committed to planting 15 billion seedlings by 2032 on degraded forest and rangeland. Doing so would bring the nation’s tree coverage to over 30 percent, said the government.

All those seedlings need bags in which to grow and be transported, and HyaPak’s seedling bags are part of the plan, said Nguthiru.

A plastic-based seedling bag has a carbon footprint of 1.6-1.7 kilograms, according to Nguthiru, and it is disposed of when the seedling is planted. HyaPak’s alternative is planted with the seedling and biodegrades, releasing nutrients including nitrogen. What’s more, during the seedling’s first months, the bioplastic slows water seeping into the surrounding soil, reducing the amount of watering required.

HyaPak Ecotech Limited founder Joseph Nguthiru with one of the company's seedling packets, created from water hyacinth sourced from Lake Naivasha.

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“You offset the carbon emissions that are going to be produced, you’ve used less water, you’ve added more nutrients … it’s a win-win situation for communities, for the planet and for yourself as a farmer,” Nguthiru argued.

HyaPak is already exporting to the US and Germany and plans to establish franchises in India and El Salvador – two countries with freshwater blighted by water hyacinth.

Nguthiru wants to create the quickest route for the world to benefit from his innovation, “Even if that means open-sourcing some of this, so that the product and development and advancement of biodegradable plastic can go really fast, so be it.”

Beyond water hyacinth, he thinks urgent action is needed to tackle the climate crisis: “Previous generations have failed us, and the ones that are coming afterwards are looking up to us. We are the ones who are going to live with a planet that’s beyond 1.5 degrees Celsius (global temperature rise),” he said.

“It’s up to my generation to come up with solutions for the climate crisis, because if we don’t do it, we are not going to do it at all.”