‘Killer fungus’ could be good news for habitats decimated by invasive moss

A new strain of “killer fungus” destroying an aggressive invasive plant has been discovered in Britain, raising hopes that destroyed habitats can be restored.

It affects heath star moss, which wreaks havoc on UK environments by taking over and destroying other species.

Scientists say this may represent a rare challenge of the British environment against an invasive species.

The scientist tracking the spread of the algaecide fungus across the UK took BBC News to see “fairy death rings” in South Wales.

Dr George Greiff, 30, made the discovery while walking on the Isle of Wight four years ago.

He spotted dead invasive algae on the edge of a cliff and took samples, but couldn’t find the killer.

But he kept seeing more cases of rotting algae. Working with scientists in England and France, he was able to put the pieces of the puzzle together.

The culprit was a potent fungus that scientists had never seen before, now called moss die-off.

We often think that mushrooms are bad, but we see it as a “beauty”.

Its victim, heather moss, is everywhere in Britain. Look at hillsides, sand dunes or a simple garden fence. “It’s an aggressive species. I’ve even seen it growing on asphalt,” says Greiff.

“It’s a nice-looking thing,” he admits, picking up pieces of a torn pile from the green moss carpet. “But that caused a lot of problems,” he says.

Approximately 2,000 non-native plants and animals have been introduced to Britain accidentally, or sometimes deliberately, by people from all over the world.

Some dominate the environment. The most famous of these is probably the North American gray squirrel, which nearly wiped out our native red squirrel population.

In the plant world, the biggest culprits include invasive Japanese knotweed, which wreaks havoc on people’s homes, or rhododendrons, which release toxins in the soil.

But not much is known about heath star moss. Scientists think it reached British territory from somewhere in the southern hemisphere in the 1940s. By 1990 it was everywhere.

“This moss just exploded. In the 1930s, native mosses were growing here instead,” explains Greiff.

There are over 1,000 species of moss in the UK. They form the backbone of our most valuable habitats, such as rarefied rainforests (humid coastal forests) and carbon-storing peatlands. But they are threatened by non-native plants.

Heath star moss sends its spores far and wide and multiplies rapidly, making it a successful invader.

“When I first saw it I had no idea what it was. I threw it in the bin,” says Grieff, who works at the Amgueddfa Cymru museum in Cardiff.

He guides me along a trail in the Bannau Brycheiniog national park near Abergavenny in south Wales.

“In heathland areas like this, native mosses have become locally extinct or their populations have declined significantly,” he says.

His eyes are fixed on the ground. He scans the low-lying shores for “death pieces.”

It reveals the ability to quietly and carefully observe plants no taller than our ankles.

Just a few meters into our walk, Greiff finds what I came to see. “It’s as big as my hand,” he says, stretching his fingers over the ring of dead brown moss.

To be honest, it was less dramatic than I expected. But our cameraman, Gwyndaf Hughes, brought a macro lens, and when I look inside, I see white spots hanging from the tips of the moss. Fungus in action.

Greiff points out that nearby baby heather plants are now able to grow in the gaps left by the rotted moss.

Greiff now knows what the beneficial fungus can do; He looks for her everywhere he goes. He jokes that the map of his location is also a map of the resorts.

“It took a lot of DNA sequencing to fully identify this fungus,” says Amgueddfa as he shows me dead moss under a microscope in a laboratory at the Cymru museum.

The fungus attaches to the stem of the moss and balloons like a candy floss around a stick. It has even penetrated into some algae cells.

He now realizes it is a close relative of the ash fungus that has killed up to 80 million ash trees in Britain.

A powerful plant-destroying fungus appears to be a potential threat to other species and biodiversity.

But Greiff’s analysis so far shows that it only affects heath star moss and, to a limited extent, another type of moss; however, more studies are needed to confirm the findings.

He believes that the origin of this fungus may be a native species that has since adapted to kill heath star moss. He says this may be “a rare example of the British environment fighting back”.

Often invasive species are deliberately targeted by humans to control them, such as in an attempt to feed gray squirrels with birth control pills.

“Some people might try to harvest this algae and get rid of it, but that’s not very effective. It would be very resource intensive and very expensive,” says Greiff.

“Having a natural biocontrol agent that does this for us is really valuable,” he explains.

Head of Plant and Earth Sciences of the Museum, Dr. Nathan Smith shows me paper envelopes of dried moss in his cupboard drawers, which contain the oldest collection of moss in the UK; some date from the 1880s.

By looking for evidence of the algaecide fungus in these samples, scientists want to determine exactly how and when it appeared.

“This fungus provides the opportunity to preserve these unique moss patches that are home to insects, fungi, molluscs and other plants,” explains Smith.

“This gives us a real chance to preserve and present their uniqueness and beauty,” he says.

Mosses are just one part of Britain’s complex biodiversity. But since our nature is classified among the most depleted natures in the world, One in six species is at risk of extinctionThe discovery that habitat destruction can be controlled is promising.

“It’s exciting in many ways. Although I’m the only one looking for the mushroom. It would be nice if others did it too,” says Greiff.