Invasive Alien Plant/Bird/Animal Infestations

[Richprins]

Good luck!

[RogerFraser]

https://www.facebook.com/groups/kruger. ... tn__=-UK-R

[Lisbeth]

Native to Sub-Saharan Africa

Why not in Kruger

[Richprins]

Insect army winning war against invasive superweed in South Africa’s waterways
Sheree Bega
27 Dec 2022


Superbugs to the rescue: Thousands of hyacinth plant hoppers, Megamelus scutellaris,, are being used to reduce and control the spread of water hyacinth on Hartbeespoort Dam and other dams in South Africa. (Delwyn Verasamy/M&G)

If dynamite does come in small packages, then living proof can be found hopping on the expanse of Hartbeespoort Dam’s polluted waters.

Since 2018, battalions of tiny bugs — biocontrol agents — have munched their way through the floating carpet of invasive water hyacinth that has clogged the dam for more than 50 years.

This 350 000-strong insect army of water hyacinth plant hoppers (Megamelus scutellaris) is winning the war on the fast-growing superweeds, reducing the cover of the problematic green plague to less than 5%.

The project’s success is now being replicated in other polluted waterways in South Africa. In total, 150 000 of the minuscule goggas have been deployed to tackle water hyacinth infestations elsewhere. 

The biocontrol blitz against the aquatic invaders is being run by the nonprofit Centre for Biological Control (CBC), a research consortium at Rhodes University. It has been joined in its mission by troops of citizen scientists, who are rearing and unleashing the hoppers in their thousands. 

The CBC said biocontrol agents such as the hopper are host-specific natural enemies, sourced from the country of origin of the weed, that can only complete their life cycle by feeding on their target weed, in this case, water hyacinth.

The adult hoppers, native to South America, measure just 3mm and pack a powerful punch. They devour the sap produced by water hyacinth. 

They pierce the plant tissue, damaging cells. Damage in the petiole (which connects the leaf blade to the stem) leads to water logging, which reduces plant buoyancy and causes the tissue to rot. This is evident once the leaves start to turn brown and a sooty mould develops on the leaves.

Dense, choking mats of water hyacinth, the world’s worst aquatic weed, choke waterways, harming aquatic biodiversity and costing millions of rands annually in control efforts.

The nutrient-enriched waters of Hartbeespoort Dam caused by poorly treated wastewater from the infrastructural collapse of sewage treatment plants lie at the root of the problem, said Julie Coetzee, the aquatic weeds programme manager at the CBC.

The dam’s waters, arguably the country’s most polluted water body, have been plagued by water hyacinth since the 1960s. Through the 1970s and 1980s, chemical control of the plant using various herbicides kept the plant populations at manageable levels, she said.

As ever-increasing nutrient pollution from Johannesburg and Pretoria was allowed to worsen, water hyacinth flourished in the presence of nitrate and phosphate contamination.

In the 1990s, biological control agents were released into Hartbeespoort Dam to reduce the rapid reproductive rates of the plants. But their effect was limited by the combination of cold winter temperatures and herbicide applications that continued until 2017, Coetzee said. 

“Cold winters and frost kill off the water hyacinth leaves and stems, which the control agents rely on as their food,” she said. “The crowns of the plants, which remain below the water surface, survive the frosts, enabling the regrowth of the plants with the onset of warmer weather.” 

But the recovery of the control agent populations lags, “so the water hyacinth has an earlier start than the biological control agents and tends to maintain this lead through the growing season.” 

Herbicides are detrimental to certain water hyacinths. “Once the herbicides are applied, the immature stages of the [biological] agents cannot escape the sinking plants and are lost. The combined effect of the winter damage and the regular herbicide sprays limited the control agent populations.”

Each water hyacinth flower produces thousands of seeds, which remain viable in the sediment for up to 25 years.

In 2018, the CBC adopted a different approach — inundating the dam with the hoppers. “This involved frequently releasing tens of thousands of the hoppers throughout the year to increase the establishment and population buildup, especially at the beginning of the summer season when water hyacinth proliferates,” Coetzee said.

This kind of release approach has the benefit of artificially increasing the biological control agent populations after a winter-induced population decline, “reducing the delay between the post-winter regrowth of the plants and the increase in biological control populations to damaging proportions”.


Megamelus scutellaris (Delwyn Verasamy/M&G)

Sentinel-2 satellite images were used to measure the reduction in water hyacinth cover from over 37% to less than 6% over three consecutive years since the hopper was first released on the dam. 

Coetzee said site surveys confirmed a corresponding increase in the hopper’s population density from fewer than 500 insects/m2 in October 2019, to more than 6 000 insects/m2 by March 2020. The CBC continued the release programme, without government funding, from the summer of 2021 to 2022. Water hyacinth was again reduced to less than 5% on the dam. 

“And now, for the first time, we have not seen reinfestation from seeds this summer,” she said. “It may still be too early in the season to tell, but it appears as though the action of the control agents has depleted the huge water hyacinth seed bank.”

Meanwhile, in the absence of the water hyacinth, another aquatic invader, the common salvinia or floating fern, has exploded on the dam. The CBC is developing a biological control agent, which is safe but damaging to the fern.

The CBC established a citizen scientist programme with stakeholders around Hartbeespoort Dam to continue the mass-rearing and releasing of the hopper, especially in spring after the large-scale germination of water hyacinth seeds.

While the CBC rears and releases the hopper from its facility in Makhanda, “we realised that establishing satellite rearing stations in close proximity to infestations of water hyacinth would be a key step in increasing the impact of this insect around the country”, she said.

All this approach needed was the buy-in from committed stakeholders, a greenhouse tunnel and containers to rear the plants and insects, and regular input from the CBC team. 

“The release effort of the hopper was increased significantly, allowing the CBC to focus our releases further afield where water hyacinth remains problematic.”

Based on the success of the Harties’ rearing programme, CBC has set up rearing stations in the North West, Gauteng, Mpumalanga, KwaZulu-Natal and Eastern Cape, all with local people’s input and support.

The CBC runs a Facebook page with regular updates about its hyacinth programme. “Through this social media platform, we are contacted by individuals and organisations who also struggle with water hyacinth invasions, and we are able to either send them insects for release, or assist in the set up of a rearing station.” 

This has been instrumental in establishing a management programme for the Ekurhuleni metro whose water bodies from Springs, to Benoni and Boksburg have been plagued with water hyacinth for years, she said. This month, hoppers were introduced at President’s Dam in Brakpan.

And, after an extended hiatus, the unit was once again funded by the department of forestry, fisheries and the environment. 
Sewage the main cause of hyacinth invasion 

A new study by hydrogeologists at the University of Pretoria used isotopes to pinpoint the root of Hartbeespoort Dam’s water hyacinth problem — effluent from sewage works, mainly those servicing Johannesburg.

Ryno Germishuys, a MSc student in hydrogeology, collected plant and water samples from the dam, and from the inflowing Crocodile River and nearby boreholes. The dam’s surface water was found to contain high volumes of faecal bacteria such as E coli, typically found in mammal and bird waste and untreated sewage. 

He conducted a nitrogen isotope-related analysis of the plant material, with his results indicating that human faeces and manure, rather than industrial or agricultural pollutants, are the major sources of growth-stimulating nitrogen still flowing into the dam. 

He said this was worrying because the build-up of nitrogen and other nutrients in water causes eutrophication, which depletes oxygen levels and affects fish and plants.

The area on the dam covered by water hyacinth has been reduced to below 5% because of the Centre for Biological Control’s programme. At one stage, hyacinths covered almost 80% of the surface. 

“Results seem very promising, but continuous work and control is needed to keep the hyacinth in check and to prevent them from spreading rampantly again,” Germishuys said.

His supervisor, Roger Diamond, said such efforts are like “putting a plaster on a wound”, because they do not address the root of the water-quality problem — sanitation upstream. 

“The only way to really control Hartbeespoort’s water hyacinth problem is to maintain, upgrade, and expand municipal sewage treatment works, and to supply better sanitation facilities to informal settlements in the Crocodile River.”

https://mg.co.za/environment/2022-12-27 ... fX-2WrE2qA

[Lisbeth]

“The only way to really control Hartbeespoort’s water hyacinth problem is to maintain, upgrade, and expand municipal sewage treatment works, and to supply better sanitation facilities to informal settlements in the Crocodile River.”

If the main problem does not get resolved...... Much easier to release a load of insects What is going to happen if one day there are no more water hyacinths to eat? What are these millions of voracious insects going to eat?

[Richprins]

The insects are specialised and just die, theoretically, Lis!

[Lisbeth]

Theoretically?

[Lisbeth]

Massacre at Marion: Mouse eradication project gathers pace


Wandering albatrosses on Marion Island. (Photo: Ben Dilley, courtesy of Mouse-Free Marion Project)

By Yves Vanderhaeghen | 27 Sep 2023

The team spearheading an operation to rid Marion Island of mice which are annihilating seabirds and other life say the project’s success is vital for conservation.
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• Marion Island is home to millions of seabirds from 28 species.

• Mice are putting 19 species at risk of extinction.

• Mice are now attacking adult Wandering Albatrosses, imperilling the bird’s survival on Marion.

• Six hundred tonnes of poison bait is to be distributed across the island.

• The funding target to launch the operation is $25-million.

Mouse attacking the crown of the head of a wandering albatross. (Photo: Stefan Schoombie, courtesy of Mouse-Free Marion Project)


Grey-headed albatross, ‘scalped’ by a mouse on Marion Island. (Photo: Tom Peschak, courtesy of Mouse-Free Marion Project)

A“zombie apocalypse” has been playing itself out on Marion Island in the Southern Indian Ocean for more than a decade, as flesh-eating mice massacre vulnerable seabirds, having already laid waste to invertebrates and otherwise tenacious vegetation.

The urgency to do something about it has been growing, but the process of conducting feasibility studies on island rodent eradication, meeting regulations and trying to raise the funds for a massive extermination operation has been a slow one.


Mark Anderson, CEO of Birdlife SA which is spearheading the Mouse-Free Marion project. (Photo: Courtesy of Mouse-Free Marion Project)

Mark D Anderson, the CEO of BirdLife South Africa – which has been spearheading the Mouse-Free Marion rodent eradication project in conjunction with the South African Department of Forestry, Fisheries and the Environment – is adamant, however, that a terminal blitz on the rodents will take place soon.

The high stakes justify the painstaking progress, because, says Anderson, “the outcome is binary: either we succeed or we fail. A pregnant mouse remaining is failure. Two mice of opposite sexes remaining is failure. So, we’ve got to do everything in our power to make sure we’re successful.

“It is after all an almost half-a-billion-rand project. And if we’re not successful, how long will it be before the work is undertaken again? Decades, perhaps.”

Anderson and Mavuso Msimang, the chair of the Mouse-Free Marion Non-Profit Company, will be giving a presentation on the crisis on Marion Island at the annual Oppenheimer Research Conference, which this year takes place from 4-6 October in Midrand, Gauteng.

The title of the presentation is, “Saving Marion Island’s seabirds – the world’s most important bird conservation project”.

An isolated volcanic outcrop about 2,000km from Cape Town, Marion Island, with its sister, Prince Edward Island, was declared a Special Nature Reserve in 1995 and falls under South Africa’s stewardship.

South Africa established a research station on Marion in 1948.

Marion is a perfect breeding ground for seabirds, although, between the relentless winds associated with the Roaring Forties and icy temperatures, it is hostile to terrestrial animals and plants.

However, its 30,000-hectare surface (roughly 30,000 rugby fields) teems with birdlife.


Wandering albatrosses on Marion Island. (Photo: Tom Peschak, courtesy of Mouse-Free Marion Project)

Ornithologists estimate that the island is home to millions of seabirds from 28 species, including penguins, giant petrels, diving petrels, storm petrels, terns and prions. But it is also called “Albatross Central”, as it is the breeding ground for about a quarter of the world’s wandering albatrosses, as well as the grey-headed Albatross, the sooty albatross and the light-mantled albatross.

Marion is not an impregnable fortress, however, and researchers have found that it is now home to 46 alien species, of which 29 are invasive.

One of these, and the only mammal among them, is the house mouse – Mus musculus.

The mice most probably jumped ship from seal-hunting brigs in the early 1800s, about 150 years after the island was first sighted by the Dutch East India Company in 1663.

It didn’t take them long to take over.

William Phelps, a sealer who spent time on Marion from 1818-1820, wrote that “… the whole island was infested with common house-mice, which had… been introduced from some sailing vessel, probably with the stores of the gang; and they had multiplied until their name was legion.

“They thickly populated the beaches, and inhabited the caves; they burrowed with the birds in the banks, and were found among the snows of the mountains.”

It is not clear how anything survived this invasion, but it is thought that an equilibrium of sorts was maintained until, Anderson reckons, climate change enabled the mice “to breed more regularly over a longer period and have bigger litter sizes”.


Mark Anderson, CEO of Birdlife SA which is spearheading the Mouse Free Marion project. (Photo: Courtesy of Mouse-Free Marion Project)

Not to mention the cats which, introduced in 1948 to kill off the mice at the research base, bred so furiously that they, in turn, were “hunted, trapped, and had a virus let loose on them” until by 1991 there were none left. Apart from mice, the cats were also killing half a million seabirds a year.

Conservationists then had to look at what could be done about the mice.

Successful eradication operations have been carried out on rabbits, rats and mice on Macquarie Island in the Pacific Ocean, rats on the Shiants in the Hebrides, and St Agnes and Gugh in the Isles of Scilly.

The biggest project was on South Georgia island in the Atlantic Ocean, which in 2018 was declared free of rodents.

In the 20 years up to 2018, the number of mice on Marion increased by about 430%.

As a result, says Anderson, “the frequency of mouse attacks is increasing very significantly. It’s exponential, and it’s related to the fact that the invertebrates on which the mice used to prey have been decimated, so the mice are feeding off the seabirds and their eggs as an alternative food source” to replace their diet of weevils, moths and seeds.

In a 2015 study, mice were found to be killing one in 10 albatross chicks.

Not only has this escalated, says Anderson, but “one of our concerns is that the mice are now starting to feed on adult wandering albatrosses as well.

“The loss of chicks obviously has a big impact, but once you start killing adult birds of breeding maturity, then the impact on populations increases. And this is a more recent phenomenon.”

These deaths are not a clinical process.


Wandering albatross chick. (Photo: Otto Whitehead, courtesy of Mouse-Free Marion Project)

The mice “nibble” mercilessly on chicks through the night. If they survive, they will spend the day exhausted, in pain, trying to recover until the mice attack again the next night.

The mice will also “scalp” the older chicks, as videos first taken in 2009 showed, attacking the crown of the head as the bird attempts to protect itself.


‘Scalped’ Wandering albatross chick being attacked by a mouse. (Photo: Stefan Schoombie, courtesy of Mouse-Free Marion Project)

Attacks on adult birds are aimed at the rump and wings, eventually felling them so that a feeding frenzy is launched at the stomach and the bird is eviscerated.

“It’s an absolutely gruesome death,” says Anderson.

Wildlife photographer Thomas Peschak described the horror in a 2019 National Geographic podcast: “All of a sudden in this landscape of black and green and grey there is this red that pops out at you… and you’re just going, ‘Well, what is that?’ You come around this boulder and you are looking at a bird that has been scalped.

“The entire back of its head and the entire neck have been eaten away.”

He added: “I’ve watched every single season of The Walking Dead and this is rougher than any one of those episodes.”

Little wonder that ecologist Otto Whitehead dubbed this a “zombie apocalypse”, which is putting 19 of the 28 seabird species breeding on Marion Island at risk of extinction if nothing is done.


Night camera shot of a mouse attacking a great-winged petrel. (Photo: Stefan Schoombie, courtesy of Mouse-Free Marion Project)

He notes that “one only needs to look at Gough Island to see how bad things can get in terms of impact on the survival of albatross chicks. Marion is not there yet, but it is heading that way and the eradication is crucial to preventing things from getting out of hand.

“There is a chance that the eradication will fail, of course. But there is also a good chance that it’ll succeed. It’s a much less complicated environment (in terms of habitat complexity) than Gough Island, where the eradication attempt failed.”

Prof Peter Ryan, one of the project’s scientific advisers, stresses that “the need to act has been ramped up this year. Reducing chick production will wipe out populations, but over a very long time. But killing adults, it will go a lot quicker.

“This year we suddenly had seven adult deaths, in an area that wasn’t being monitored closely, so we don’t know how many attacks there were to result in seven deaths. That is a game changer.

“The first wanderer attacks were recorded in 2002, but they were very sporadic. The first attacks on sootys were in 2009, and then in 2014-15, we had big outbreaks of attacks on the light-mantleds and sootys. And it’s taken off since then.”


Two grey-headed albatrosses ‘scalped’ by mice on Marion Island. (Photo: Ben Dilley, courtesy of Mouse-Free Marion Project)

Ryan cautions that while attention is on the damage to birdlife, “the impact on invertebrates has been even more devastating, and this has been clear for 20 to 30 years, but people don’t care about invertebrates so it’s hard to muster a lot of support”.

Of those that are hardest hit are endemic weevils and the flightless moth.

There are two species of flightless moth on Prince Edward, and only one on Marion, he says, “so we suspect that probably Marion has lost one entirely already due to mice. You really struggle to find a flightless moth on the island now.

“It’s desperate what the mice have done to the invertebrates; they’re just strip-mining the island of them.”

What is to be done?

It’s clear that a few mousetraps won’t suffice.

Eradication is seen as the only solution, and the process to achieve this started in 2015, says Anderson, when a feasibility study was commissioned, “but it’s only in the last three years that things have really started moving”.

It will be a massive task.

“The mice are found across the island, and this would be the largest island by a large margin from which mice have been eradicated in a single attempt if we’re successful.

“Logistically, Marion Island presents some challenges. It is 30,000 hectares for starters, so that’s big. Then, there is no port, so everything has to be taken from the ship to the island by helicopter.

“It will take about 10-20 days to offload the gear, the helicopters and the team, depending on the weather conditions.

“You’re flying helicopters in pretty difficult flying conditions, with strong winds in particular. We’ll use six helicopters, which will spread almost 600 tonnes of bait over every square metre of the island.”

The eradication operation is being run by New Zealander Keith Springer, who has had extensive experience in rodent eradication. The project is managed by Dr Anton Wolfaardt, who has more than 20 years of experience working in the Antarctic and sub-Antarctic.

Springer says that the Department of Fisheries, Forestry and the Environment’s polar research vessel SA Agulhas II, which is used to resupply the scientific bases at Gough and Marion Islands and in Antarctica, will deploy the eradication team and pick them up again.

South African helicopter companies will shortly be invited to tender for the project implementation.

Springer points out that the bait is not just dumped by the helicopters, as a water-bomber might do on a fire.

“We use a bucket slung beneath the helicopter to disperse the bait. Below a hopper which holds the bait is a motor-driven spinner. The bait falls into the spinner and is flung out in a 360o pattern. We expect that each bucket will be able to deposit a swath of bait about 80 metres wide.


Bait bucket viewed from a helicopter. (Photo: Courtesy of Mouse-Free Marion Project)

“We fly in parallel flight lines across the whole island distributing bait, and then do it again, from a slightly different angle. The objective is to get a bait pellet in every potential mouse territory on the island. This is where some of the pilot skills come in – it’s not easy to stick absolutely on a plotted line shown on your instruments, without deviating more than a couple of metres either side of the line, and do that all day.”

This can only happen, says Anderson, if the weather cooperates.

“The team will be on the island for the better part of five months, and they will wait for two weather windows. We’ll have top meteorologists watching the weather, and when there’s a week to 10-day weather window, they’ll be ready to roll.

“They’ll fly the helicopters during that period. Then they’ll do a second bait drop during a subsequent weather window a few weeks or even months later.”

The bait used comprises a cereal matrix, with an anticoagulant rodenticide poison, Brodifacoum, in it.


Six-hundred tonnes of poison bait will be distributed across the island, using bait buckets suspended from helicopters. (Photo: Courtesy of Mouse-Free Marion Project)

Anderson says the work will be done in winter, when the mice are at their hungriest and when they’re not breeding.

“They’ll take the bait, which is on the surface, into their underground burrows and cache it, or consume it. The majority die underground, within three to four days.”

As for collateral damage, Anderson says there will inevitably be some.

But, “the important thing is that this is a once-off intervention. If you think about managing the Kruger Park, for example, that is forever, literally. Here, we go in, we do it well, with biosecurity in place post-eradication: job done!

“There’s almost no conservation work where you say you’re going to move in and be able to say, problem solved. That’s nice.”

The success of the operation, which will be undertaken in 2026, could only be known two years after the baiting is completed, and after sniffer dogs and cameras have fully swept the island. But failure could be signalled earlier if any mice are detected in the meantime.

There is still something standing in the way of getting rid of the mice: money.

The funding target is to raise $25-million (R469.2-million), but “we’re still about $19-million short”, says Anderson.

“We’re pulling out all the stops. The South African government has committed R60-million, with the likelihood of more”, and one of the biggest individual donors is pharmaceutical magnate Frederik Paulsen, who has donated $1.5-million. He is also a director of the Mouse-Free Marion Project NPC Board.

Asked about criticism that this operation would be a case of playing God, Anderson says that “unfortunately in this situation, one has to essentially be playing God because the problem is not going to resolve itself.

“It may be resolved when every last seabird is gone, and the mice have got nothing else to feed on, and we can’t wait till then.

“But nobody likes killing. I agonise over the things we need to do. Whether it’s removing Himalayan tahrs from Table Mountain, or dealing with house crows in Cape Town and Durban, we’ve got to think of what the long-term benefits are, as custodians of biodiversity on the planet.

“The mice don’t belong there. They need to go,” says Anderson.

They need to go because, says Mavuso Msimang, “it is imperative that protected areas serve their purpose in providing safe spaces for the species that call them home”. DM

Yves Vanderhaeghen writes for Jive Media Africa, science communication partner to Oppenheimer Generations Research and Conservation.

[Lisbeth]

Creecy launches R2.6-billion invasive species programme — experts say more funding needed in critical areas



Minister Barbara Creecy with Working on Fire Programme participants eradicating alien invasive plants in Heidelberg. (Photo: DFFE)

By Julia Evans | 24 Nov 2023

With the launch of the R2.6-billion Working for Water Programme, government is taking steps to protect its ecosystems and bolster climate resilience by controlling invasive alien species and restoring natural habitats. However, experts argue that SA needs more funding focused on fewer areas for the programme to succeed.
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“Alien invasive species take over the natural functioning of ecosystems,” said Department of Forestry, Fisheries and Environment (DFFE) Minister Barbara Creecy from Heidelberg, Gauteng last Friday, during the launch of the new R2.6-billion project, which forms part of the Working for Water Programme.

“It is for this reason our Department is happy today to announce this five-year programme to combat alien species and the damage they do to our land, wetlands and rivers.”

This programme aims to control invasive alien plants over 1.2-million hectares across all nine provinces over five years and create 38,839 work opportunities every year, primarily in rural communities throughout the country.

This project is part of the Working for Water Programme, first launched in 1995, that focuses on removing invasive alien plants and bush encroachments from critical waterways and wetlands.

According to the South African National Biodiversity Institute’s (Sanbi) latest status report on Biological Invasions and Their Management from 2019, invasive trees use 3-5% of South Africa’s runoff water every year, and many species of invasive plants are also less drought-resistant than indigenous ones.

“Invasive alien species are brought in from other parts of the world, and where they come from, originally, they have got a whole lot of pests and diseases and things, predators that keep them in check.” Dr Brian van Wilgen, ecologist and Emeritus Professor of the Centre for Invasion Biology at Stellenbosch University explained to Daily Maverick.

“When you bring them here, all of those checks are gone — that’s why they become so aggressively invasive.”

The department explained that ​​invasives threaten biodiversity, water security and quality as well as destroy the productive use of land and ecological functioning of natural systems.

Van Wilgen, who was the first Scientific Advisor to the Working for Water programme (between 1996 and 2004) explained that even though R2.6-billion sounds like a lot, there are over 200 alien invasives plants and species that need to be controlled in the country – but we’re only getting to less than 1% of that per year, while we estimate that the problem is spreading at between 7.4 and 15.6% annually.

In terms of water security, van Wilgen explained that “many of these plants, especially invasive trees, use much more water than the vegetation that they replace. In a water-scarce country like South Africa, you start running into problems”.

The plants also pose an additional threat of fuelling wildfires and increasing soil erosion if left unmanaged.

For example, van Wilgen explained that pine trees in the Cape, that have outcompeted the indigenous fynbos, can grow to 10 metres high (whereas fynbos is only one metre.)

“There’s so much more fuel to burn when a fire comes along, that the fires are very, very difficult to control, they’re much more damaging.”


Pine trees can grow up to 10 metres high, much higher than the indigenous fynbos that they’re outcompeting in the Cape – creating more fuel for fire. (Photo: PHYS.ORG / Wikipedia)

Biodiversity as a buffer against climate change

During the launch of this programme, the DFFE emphasised that invasive species interfere in natural processes that can help mitigate the effects of natural disasters through the provision of ecosystem services and that invasive species exacerbate floods, droughts and wildfires, and have negative impacts for the forestry and agriculture sectors.

“In short, biological invasions will exacerbate the effects of climate change and the extreme weather events associated with global warming,” said Minister Creecy.

“By clearing waterways and managing the spread of invasive species we are restoring natural habitats and simultaneously restoring ecosystem services that will assist us in the fight against the effects of climate change.”

For years the scientific community has been highlighting how climate and biodiversity issues are interlinked — not only do depleted ecosystems contribute to climate change, and vice versa, but strong ecosystems can be used to enhance our resilience to anthropogenic climate change.

“If you keep your ecosystems intact, whether there are climate extremes… the ecosystems will be able to cushion us from the impact of climate change,” said Shonisani Munzhedzi, CEO of Sanbi.

An example, Munzhedzi said, is how functional wetlands and functional strategic water sources can absorb extreme rainfall, an impact of climate change that will only increase in frequency and intensity in a high-carbon future.

“If it rains hard for 20 days, the water gets to be mitigated — absorbed into the wetland system, the wetland system will deal with it.”

Van Wilgen explained that invaded ecosystems don’t have the same water-holding capacity as the natural vegetation does, so if there’s good natural ground cover in catchment areas, it’s less likely to have flash runoff from that catchment area, for example.

But van Wilgen emphasised that while “alien species disrupt the normal functioning of natural ecosystems which protect us from a lot of things. they don’t act by themselves — they just exacerbate the problem that’s caused by other things as well,” — such as building dams, and pollution.

Business as usual won’t solve the problem

“South Africa is one of the few countries that has a programme like this that is tackling this problem,” said van Wilgen about the Working for Water programme.

“And so it is to be praised. But it needs to improve its efficiency and its planning.”

Van Wilgen, who was the first Scientific Advisor to the Working for Water programme (between 1996 and 2004) explained that even though R2.6-billion sounds like a lot, there are over 200 alien invasives plants and species that need to be controlled in the country — but we’re only get to about 4% of that per year, and the problem is spreading at 6% annually.

For example, van Wilgen explained that black wattles, brought in from Australia, “have invaded enormous areas, where they use a lot of water, and they displace important grazing for livestock.”

A 2016 study van Wilgen co-authored found that to successfully achieve the control of a maintenance level will either require funding to be substantially increased or if control were to focus on fewer selected areas.

Van Wilgen explained that, “most ‘business as usual’ scenarios will result in the problem running away from us.”

And instead, van Wilgen’s study suggests that management can be improved by practising conservation triage, “focusing effort only on priority areas and species, and accepting trade-offs between conserving biodiversity and reducing invasions”.

Conservation ‘triage’

Van Wilgen explained that the term “triage” comes from the Napoleonic Wars, when thousands of wounded soldiers flooded hospitals, and doctors had to divide patients into those that needed immediate treatment, those that were beyond help, and those that did not need immediate treatment.

“And we’re getting to the position now, where we have to make those kinds of decisions with our ecosystems,” explained van Wilgen. “We might not be able to save all of the protected areas in the country, but there’s quite a few that we can save if we concentrate the money in those areas and use it more effectively.”

Between 1998 and 2020, R7.1-billion (adjusted to 2020 values of ZAR) was spent by Working for Water’s projects on interventions to control alien plant invasions, according to a 2022 study van Wilgen co-authored that looks at what the Working for Water programme has achieved over 20 years.

Control efforts were directed at 178 species covering 2.7 million hectares, which is 14% of the estimated invaded area (over two decades). The study noted that over a quarter of the control was not in priority areas for biodiversity and/or water conservation.

The study found that while there has been a reduction of alien plants at a local scale, national surveys suggest that plant invasions have continued to grow: “The problem is too large to expect that control can be achieved everywhere”.

Thus, the researchers recommended that they should instead practise, “conservation triage, focussing on clearly defined priority sites, improving planning and monitoring, and increasing operational efficiency.”

For this R2.6-billion five-year project launched last week, there are projects spread through all nine provinces in SA, and our national parks.

The provincial profile of the budget and hectares for clearing over a five-year period

(To see the chart click on the title)

“You get a lot of small projects springing up all over the place, because then they can say, look, we’ve created jobs in every province,” said van Wilgen. “But then in that way, you dilute the funds to a point where they are ineffective.”

Creecy said at the launch, “I think that one of the important innovations that our department has done with this new working for water programme is that we have contracted with small enterprises in rural areas for a five-year period to clear a specific area.”

Creecy said that in the past they had very short-term contracts, and found that the alien invasives simply returned.

Van Wilgen acknowledged that the department has done some prioritisation exercises, but the National Treasury requires them to maximise the number of jobs.

“The projects that come in with the lowest cost per person per day, get preference,” said van Wilgen. “In other words, they employ more people because they spend less on other things like herbicides or management research — which upsets the prioritisation exercise even more. “

Along with conservation triage, van Wilgen’s research has suggested that more funding would be needed to control the species in perpetuity (as complete eradication is impossible in most instances).

The 2022 study found, based on several estimates, that the cost of clearing existing invasions in South Africa would require three to seven times more money than what has been spent to date.

Biological control agents

Another suggestion would be to ramp up biological control agents. Van Wilgen explained that this is when insects or pathogens control the growth of the species.

“If you were really serious about the problem, I would spend 10 – 30 times more on biological control than you are because it holds so much promise,” said van Wilgen, “the problem is it doesn’t immediately create a lot of jobs”.

Van Wilgen explained several examples of where biological control agents brought a species under complete control is not a problem anymore.

The biggest success story was bringing prickly pear cacti under control in the 1930s. Van Wilgen explained that prickly pear cactus infestations had driven farmers off their land, and the biological control was so successful that within a couple of years, they were able to return.

In Kruger Park, insects were able to bring substantial contribution to the control of a type of cactus (Opuntia stricta) in residual infestations of the weeds that have been treated with herbicides.

Another example is with the water hyacinth at Hartbeespoort, where it was found that under the right circumstances, very good control can be achieved with “inundative release strategies” — i.e. releasing large numbers of insects at once. DM

[Lisbeth]

Rapid water lettuce spread threatens Vaal River — weevils could be the solution


Water lettuce, an invasive species, was contained in the Taaibos tributary by a floating barricade locals put in place, before the species could float into the Vaal River. (Photo: Brandon Stuart)

By Julia Evans | 31 Jan 2024

The Vaal community is scrambling to halt the spread of water lettuce, an invasive alien species threatening the Vaal River. There is a clear solution to deal with these floating plants, but a new regulation threatens to slow the process.
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‘We have a very limited window of opportunity to urgently remove this water lettuce, which is currently very accessible,” said Rosemary Anderson, who has spent her whole life living alongside the Vaal River.

Water lettuce, an invasive species originating in South America, began to spread in the Taaibos — a small tributary stream that runs into the Vaal River — before being contained by a floating barricade erected by residents.


The Taaibosspruit (a tributary of the Vaal River) is inundated with alien invasive species, with water lettuce covering the stream for kilometres. (Photo: Julia Evans)


Vaal River residents have bottlenecked the spread of alien invasive species (water lettuce and some water hyacinth) on the Taaibosspruit, trying to stop the spread of the species into the Vaal River using a buoy system. (Photo: Julia Evans)

Before the barricade was put up, however, the plants floated into the Vaal River, and now span about 25km of the river, from the mouth of the Taaibos towards the Vaal Barrage.

“If this water lettuce is allowed to pass past the barrage, it then has a free journey of approximately 1,000km of middle and lower Vaal River, the Bloemhof Dam and then into the Orange River,” said Anderson, who owns the garden restaurant Stonehaven on Vaal and is the chairperson of the hospitality association Fedhasa.


Water lettuce is an alien invasive species from South America. It can affect local water biodiversity, human wellbeing, business, tourism and the broader environment. (Photo: Julia Evans)

“Many towns, communities and farmers abstract from these waterways for both drinking water and irrigation. This will have a significant negative impact on them. That is why this is a national crisis,” Anderson said.

Anderson and her community began noticing water lettuce on the river in 2021.

• 
  Water lettuce, which is an invasive aquatic species, is harmful to ecosystems because this species blankets the water body, forming a "mat" of just leaves.
  
  This blocks out sunlight, which any healthy aquatic ecosystems needs, stopping plants and phytoplankton from being able to photosynthesize - where they produce oxygen.
  “So if you don't have any oxygen being produced, you're not going to have life,” said Coetzee, explaining that all water life - like fish, and aquatic insects will die because there's very low oxygen.

Anderson emailed Rand Water, which said it was not its mandate.

Because the water lettuce died each winter, it wasn’t a huge concern. But this past summer, in December, residents reported a “dramatic change”, with water lettuce and water hyacinth coming down the Taaibos Spruit and moving into the main river.

“I do hope that the DWS [Department of Water and Sanitation] and Rand Water appreciate that time is of the essence and every day more water lettuce is flowing past the barrage and unnecessarily polluting downstream of us,” Anderson said.


An extraction team manually removes water lettuce from the Vaal River at Malbank on 29 January 2024. (Photo: Laurel Young)

The Vaal River community has a WhatsApp group with more than 100 members, who have begun removing tonnes of water lettuce from the river.

The US University of Florida’s Center for Aquatic and Invasive Plants says, “Water lettuce forms dense mats that clog waterways making boating, fishing, and other water activities, impossible. These mats also degrade water quality by blocking the air-water interface and greatly reducing oxygen levels, which can result in fish die-off and the overall reduction of aquatic fauna and flora diversity.”


Residents along the Vaal River have been removing several tonnes of water lettuce a day from the river in an urgent attempt to stop the rapid growth of this invasive species. (Photo: Julia Evans)

Laurel Young, the owner of the Vaal River Lodge in Northdene, told Daily Maverick that she has a team that manually removes four 8-tonne truckloads of water lettuce a day.

Anderson came across the concept of biological control agents, which have eradicated aquatic invasive species like water lettuce across South Africa for decades.

She contacted Dr Julie Coetzee, the deputy director at the Centre for Biological Control at Rhodes University about the Vaal River problem.

Coetzee told Anderson that they had also approached Rand Water in 2021, when the water lettuce first appeared, to initiate a biocontrol, which uses insects or pathogens to control the growth of invasive species, but said that because of staff changes at Rand Water, the measure was not implemented.

The solution — weevils

Water lettuce weevils can be used as biological control agents to control the expansion of the invasive plant species. (Photo: David Taylor / Centre for Biological Control)

“Water lettuce biocontrol is one of the best biocontrol programmes against invasive weeds in the world, but we need to ask people to be patient,” said Coetzee.

She explained that while manually removing plants from key areas, like boat access points, was possible, the plants’ growth rate was far too quick for this method to control the spread, and any plants left behind in inaccessible places would reinfest.

Biological control, in this case using water lettuce weevils, can lower the growth rate, reduce the size of the plants, and get into every nook and cranny where the plants are. Weevils feed on and tunnel into the leaves of invasive species, causing them to become waterlogged and sink.

Coetzee explained that specific species of weevil target only water lettuce, whereas the other two methods of dealing with aquatic invasive species, chemical sprays and herbicides, can kill anything living in the water after the plants sink, as well as bank vegetation and indigenous plants.

The biggest negative side of biocontrol is how long it takes.

“So you really have to convince people that this is the most sustainable option to get rid of [the water lettuce], with fewer side effects than any other control option,” Coetzee said. “In a world of instant gratification, we need to be patient.”

Coetzee said the insects’ reproduction and feeding rates would slow during winter and it would probably take two seasons for the weevils to eradicate the plants.

​​A tried and tested method of success

The Centre for Biological Control’s Sisonke Programme has successfully used weevils to control invasive species throughout SA and the method has also proved successful in other parts of Africa, Australia and the US.

Water lettuce eradicated with weevils in Orpen Dam, Kruger National Park
January 2008 - January 2010 (Click to see "before and after")

At Hartbeespoort Dam, water hyacinth was controlled with “inundative release strategies”, whereby researchers help local people breed hyacinth insects on site and release them into the dam.

So, once the water lettuce weevils are sent to the Vaal, residents, along with Rand Water, will need to implement their own “rearing stations” to keep growing the insects.


Employees, part of the Centre of Biological Control, at Rhodes University in Makhanda, work in the rearing station to breed weevils as biological control agents. (Photo: David Taylor / Centre for Biological Control)

“Instead of saying, ‘What’s the government doing about this?’, [people] can say, ‘Well, look what we’re doing about this,’” Coetzee said.

Rand Water told Daily Maverick they had identified a rearing station at one of its sites that allows for heating in winter, and would fund this part of the project.

Sasol, which has a chemical plant near the Vaal River, has approached Rand Water to explore opportunities to assist with the control of aquatic invasive plants.


The Centre for Biological Control Sisonke Programme employs 10 people living with disabilities from Makhanda to rear biological control agents (such as weevils). (Photo: David Taylor / Centre for Biological Control)

DWS spokesperson Wisane Mavasa told Daily Maverick, “A combination of biological control and chemical control is a more environmentally sound approach to dealing with these plants compared to chemical spraying only.”

She said the plants would be sprayed when the insect population reached 60-80% of the plant mass, explaining that spraying before this would lead to a toxic bloom.

New red tape

While the Centre for Biological Control helped community partners get permits from the Department of Forestry, Fisheries and the Environment (DFFE) to rear weevils on their property, they never had to apply for permission to release the weevils into the water — until new authorisation was gazetted by the DWS in December.

Rand Water told Daily Maverick that they had applied to the DWS for the necessary authorisation and had had several meetings with authorities.

“In the meetings [with the community] the urgency of the application has been stressed. Rand Water awaits a response from DWS on the agreed approach to take, and will then complete the necessary risk matrixes, studies and documents,” Mbuyiswa Makhubela from Rand Water said.

“If this was deemed a national emergency — which it is — then surely immediate action could be taken,” Anderson said.

“We are talking weeks, or maybe months [until biological control can be implemented] if this bureaucratic process is followed.”

Who’s responsible?

While more than 100 people on the Vaal River are willing to tackle this issue in pursuit of saving the river they love, whose responsibility is it?

The answer is tricky, Coetzee said. The DFFE should be the one controlling invasive species because its Working for Water programme originally funded biological control.

The DWS said it had a memorandum of agreement with the DFFE to ensure control of aquatic invasive species.

At the end of 2023, DFFE Minister Barbara Creecy launched a R2.6-billion programme for the manual removal of terrestrial (land-based) invasive species.

Coetzee said removing aquatic plants manually would be “a waste of time and money because they just keep growing. You remove a hectare today, and tomorrow it’s back because of the rate at which these plants grow.” Biological control would be a better investment.

Dr Brian van Wilgen, an ecologist and emeritus professor at the Centre for Invasion Biology at Stellenbosch University, agreed: “If you were really serious about the problem, I would spend 10-30 times more on biological control than you are because it holds so much promise.”

Rhodes University’s Centre for Biological Control previously had a contract with the DFFE to implement biological control programmes across South Africa. DFFE spokesperson Michael Mokoena told Daily Maverick that the contract had expired in 2021 and a new tender was initiated.

The Centre for Biological Control wasn’t awarded the tender, but its application is still in the mix.

Mokoena said the DFFE does have a programme for the release and monitoring of biocontrol agents in South Africa, including the Vaal River, but Vaal residents say it hasn’t implemented a programme to combat the water lettuce.

As the land owner of the Vaal Barrage, Rand Water also has a responsibility to control invasive species, and said it is engaging with the Centre for Biological Control and the DFFE “to ensure that the introduction and release of biocontrol agents is undertaken as soon as possible”.

The problem below the surface

Professor Anthony Turton, a water resource management specialist at the University of Free State, told Daily Maverick that while biological control was a good solution to get rid of invasive species, it was akin to treating a symptom while ignoring the underlying illness.

Turton said aquatic invasive species were expanding at such a rate because of water eutrophication, which is the “explosive growth of microorganisms, to the extent that dissolved oxygen is depleted”. This created an ideal environment for plants such as water hyacinth and water lettuce to grow.

Dr Samuel Motitsoe, an aquatic ecologist based at Wits University, said water eutrophication was a serious concern for human and wildlife health and aquatic biodiversity. He believed the combination of untreated raw sewage and agriculture run-off was causing the high level of nutrients in the Vaal River.

The DWS agreed, adding that along with sewage and agriculture, run-off from informal settlements, illegal discharge of waste and industrial processes contributed to the eutrophication of water.

“The problem is extremely big in South Africa and prevalent in 80% of the dams in RSA,” Mavasa from DWS said.

Nearly two-thirds (64%) of South Africa’s sewage and wastewater treatment works are at “high or critical risk” of discharging partially treated or untreated water into rivers and the environment, according to the latest Drop reports from the DWS, published in December.

Three wastewater treatment works — Reitspruit, Sebokeng and Leeuwkuil — in Emfuleni discharge effluent into the Vaal River and its tributaries.

While the functioning of these three plants has improved slightly since DWS appointed Rand Water to manage, upgrade and repair them in January 2022, none is up to scratch. As the regulator said in the 2023 Green Drop report, “All three works have poor quality effluent which negatively impacts downstream communities and the receiving environment.”

This means that dealing with the invasive plants will not solve the problem of the eutrophicated water. A further problem is that removing the floating plants that are blocking the sun will cause the proliferation of cyanobacteria, which has toxins that can cause respiratory illnesses.

“It’s a wicked problem,” agreed Coetzee, saying that first and foremost, water quality needed to be improved.

The DWS said they had a eutrophication strategy to improve water quality, had reintroduced the Green Drop report to identify key deficiencies and had initiatives to increase plant capacity. DM