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Aliens on our Doorstep

Japanese knotweed - Photo Credit, Philip Precey

A foggy morning in the Colne River Valley near Huddersfield is not where you’d expect to find aliens. Yet, within minutes Howard Roddie, on his 'most dangerous' Telling our Story assignment to date had spotted some not so little - but very green alien plant life.

War of the Worlds

At the end of the HG Wells classic, the martians that have conquered Earth emerge from their spacecraft and die as our unfamiliar microbes infect them. The mortality rate is 100%. Imagine how bleak this story would have been if it was the other way round and diseases carried by the alien invaders wiped out humanity. For the UK's only indigenous Crayfish species - the White-clawed crayfish, this bleak outlook is reality. 

The alien in this case is the American signal crayfish, brought to the UK in the 1970’s for aquaculture farming. Of course, they escaped, and unleashed the fungal crayfish plague on our White-clawed crayfish - the mortality rate is 100%. The American signal crayfish are immune and is now the only crayfish found in most UK rivers. Furthermore, many of the other Crayfish found in the UK are also invasive species. The good news, in this rather bleak outlook is that we can all do our part to help control this. 

A foggy morning in the Colne River Valley near Huddersfield is not where you’d expect to find aliens. Yet, within minutes, on this X-files style Telling our Story assignment, I’d spotted some not so little but very green aliens. I’m not talking about Bill and Elliot, my hosts for the day, but the Himalayan balsam and Japanese knotweed that would blight the valley were it not for the efforts of Bill, Elliot and the rest of the Yorkshire Wildlife Trust INNS (invasive Non- Native Species) team. 

The Huddersfield Narrow Canal - Howard Roddie

The Huddersfield Narrow Canal - Howard Roddie

Our Army - INNS Team

The INNS team tackle and track a long list of invasive species, plants and animals alike.  There is a long list of non- native species that flourish in the UK climate and threaten our native wildlife. Typically, we have to tackle Himalayan balsam, Japanese knotweed, giant hogweed, American signal crayfish, floating pennywort and many others. They all carry diseases, out-compete our native species, block oxygen from canals and rivers, injure people and even reduce the value of our homes.

I met Bill Hargreaves (INNS volunteer) and Elliot Baxendale (YWT Project Officer - Network 4 Nature) to see some of the work the INNS do and the impact it is having. We focused on two species  - Himalayan balsam and Japanese knotweed) that impact the Colne valley, but over the course of the day we discussed many others.

Firstly, though, let’s meet Bill and Elliot.

Bill INNS Volunteer - Howard Roddie

Bill is seeding the bank with native species (half grass, half wildflower) where Japanese knotweed was once rampant - Howard Roddie

The INNS Army volunteer - Bill

Bill knows the Colne valley and the area around Marsden well, having spent 15 happy years as the areas postman. He knows every route and everybody in the area. Bill and I have something in common. We both retired in early 2022 and started volunteering for Yorkshire Wildlife Trust following the 2022 Members AGM at Escrick. Bill was inspired by meeting his old York University biology department lecturer, John Lawton at the AGM. Sir John, as he is now known, also happens to be the Yorkshire Wildlife Trust President. So, one day, Bill just turned up at Stirley and asked if he could get involved. He never looked back, and eventually got involved with the INNS team. Bill doesn’t just volunteer with the Trust, he is also involved with many other groups and projects. For instance, he volunteers at Leeds unique Hyde Park Cinema and the Electric Theatre Cinema - a community pop-up cinema in Marsden. He has also been involved in the Leeds 2023 City of Culture, the Leeds International Film Festival, Marsden Jazz Festival and many others.  Bill pointed out that the great thing about volunteering is that you only have to do things that you really enjoy and have a passion for. 

Elliot INNS - Howard Roddie

Elliot finds a small piece of knotweed, this will be treated once the conditions are right - Howard Roddie

The INNS Army YWT Project Officer - Elliot

Elliot has previous experience of alien species. He ran his own tree surgery business named after the ultimate invasive species, 'Triffid Trees!'

Elliot also studied Environmental Science with The Open University. So, when a post came up in the INNS team, he was a natural candidate. Not only did he have the practical and theoretical background, he also understood the nature of contract work and engaging landowners.
 

The Battlefield

We walked down the side of the Huddersfield Narrow Canal which runs parallel to the River Colne. Unlike the normally shallow Colne, the canal is navigable due to the constant depth and 74 locks over its 19-mile length.

The orange spots you can see on the image below, taken from the INNS mapper website has been recorded mainly by the INNS team and indicates invasive species on the river Colne. The Huddersfield Narrow Canal looks like it’s relatively INNS free, but this is most likely due to it not being so extensively surveyed and reported to the INNS Mapper.  The slow-moving water prevents the spread of INNS downstream, but as boats move upstream through the canal, invasive species can move with them, even through the locks. Whilst easy access due to wide paths on the canal makes management relatively straightforward on the canal, the close proximity to the Colne means we have threats on both watercourses from upstream and downstream movements.

As we turned away from the canal onto the river bank, the undergrowth increased. Steeper banks, less well defined paths and fast flowing water combine to allow the INNS to spread quickly. 

INNS Mapper

The orange spots showing the extent of the invasive species on the River Colne, mainly recorded by the INNS team - Image Credit, INNS Mapper

Here, in the image below - we can see Japanese knotweed poking out from the Brambles, Some yellow from previous treatments, some yellow with autumn. Isolating the knotweed for treatment is just one of the challenges faced by the INNS team. Whilst the orange dots on the map indicate total INNS dominance, this is not the case. The INNS team is constantly recording invasive species in order to be able to monitor and treat them. Today, we were surveying and re-seeding. It was too damp to apply any treatments. The main species we saw were Japanese knotweed and Himalayan balsam.

Japanese Knotweed - Howard Roddie

Japanese knotweed growing through brambles - Howard Roddie

Himalayan Balsam Carys Hutton

Himalayan balsam - Photo Credit, Carys Hutton

The Enemy Number 1 - Himalayan Balsam

Balsam Bashing is one task that nearly all YWT taskday volunteers do during the summer months. Initially very satisfying as great piles are cleared from small areas, it can be dispiriting to go back two weeks later and see others have regrown in their place. If only we had another weapon… well, there is hope on the horizon. The key to balsam’s success in the UK is competitiveness. It is shallow rooted, fast growing, hollow stemmed and composed mainly of water. Its native habitat conditions of Asia are much tougher. Including higher altitudes, a shorter growing season and the presence of a local fungus all contribute to help contain the balsam. Over here though, it out competes everything, especially as the UK does not have the naturally occurring fungus which is needed to restrict its growth. And, there lies the key. The fungus has been identified and is being carefully piloted as we have to be sure it doesn’t impact local species and become an INNS in itself. 

Elliot explained -this isn’t a magic wand. They cannot just hose the fungus onto Balsam and see it wither away instantly like saltwater in the John Wyndham book “The Day of the Triffids”. This will take many years. Firstly, much of our Balsam is hybridised which means we have to rely on the fungus being able to adapt to the hybridised versions. Also, it will be released into the wild in a controlled manner, from the highest possible point upstream with the aim of letting the wind spread the fungal spores naturally. If successful, this will reduce the dominance of Himalayan balsam and will require far less management.
 

Japanese Knotweed - Philip Precey

Japanese knotweed - Photo Credit, Philip Precey

The Enemy Number 2 - Japanese Knotweed

Japanese knotweed, on the other hand, has no natural predator or inhibitor that we can employ to limit or eliminate its spread. Its main competitive advantage apart from its fast growth and ability to take advantage of Yorkshire climate is the remarkable ability to grow from fragments. It never seeds in the UK - it doesn’t need to. It only spreads through fragmentation and rhizome expansion. If it is disturbed, it can grow back from a piece of root or stem.

The INNS Mapper website puts it this way - do not strim, shred or attempt to compost this plant!
So, we can’t bash it either. Its roots are deep and we risk doing more harm than good. Additionally, Japanese Knotweed can grow through cracks in concrete and roads widening small fractures causing structural damage. If you get it in your garden, your house could be at risk. It is also the landowner’s duty to report and control it - a long, expensive and uncertain process.  As a last resort when all other options have been explored the only other weapon for treating Japanese knotweed on watercourses is to use the pesticide - Glyphosate which is used sparingly in extreme cases as a last resort. In order to use this staff have received specialist training and wear full protective clothing to keep them safe. 

In the Colne Valley project area, the INNS team will treat the knotweed at cost. Elliot finds and informs the landowners. Most are aware of the problem and grateful of the help and the reduced cost our INNS team. This is down to the good relations that have been built over the years between the INNS team and the local landowners. However there are still stretches of the riverbank that cannot be treated as the landowner can’t be found. Of course, it is then all inter-linked as not being able to treating the areas containing Japanese knotweed in turn increases the risk for the treated areas - due to the agressive way in which Japanese knotweed can spread. 
 

Elliot re-seeding with native wildflowers - Howard Roddie

Here we see Elliot wading back from an area that was treated earlier this year - the area is inaccessible from the other side. The river was in flood at this time, so Elliot had to be careful. If Bill wasn’t there to monitor the situation, Elliot would not be able to cross the river. Elliot continues to monitor the area and re-seed with a mixture of grass and native wildflowers. Photo Credit - Howard Roddie

An Army Marches on its Stomach

After a morning spent on the river banks and surrounding environment we decamped to Katie's Homemade Kitchen in Marsden for hot drinks and a debrief. This is where Bill and Elliot told their stories and filled me in on many other invasive species. - American signal crayfish, giant hogweed, muntjac and sika deer amongst others.

Interestingly, I was volunteering in a shoresearch species count a few days later on the coast in my other volunteering role with Yorkshire Wildlife Trust and we came across Darwin’s barnacle - another invasive species from Australia that is outcompeting our native species with unknown consequences.

Dirty Boots Kill Crayfish

Prevention is better than cure. We can all do our bit to repel invaders. It’s all too easy to transfer Invasive crayfish plague, pieces of knotweed or Balsam seeds from one place to another.

To help reduce the spread of INNS through a catchment and to protect particularly vulnerable native species such as White clawed crayfish, we must always follow the Check-Clean-Dry protocol (below) to ensure our kit is as clean as possible when we move between areas. This is especially important if you enter a watercourse or work in close proximity to a river bank.

Even if you’ve been bashing balsam or working near knotweed - Check-Clean-Dry every time and that will help stop the stop the spread, afterall - you wouldn’t want to be bringing any of these alien speices home...would you?

INNS Advice

The Check-Clean-Dry protocol helps to stop the spread of INNS

You can help us to win the battle against invasive spieces by using the new INNS Mapper app and website .

INNS Mapper is an app and website where you can report sightings of INNS, which will help to survey and manage INNS (invasive non-native species) in England, Wales and Scotland.

INNS Mapper is free to use and aims to provide an effective resource to support INNS programmes and coordinate efforts across multiple organisations. The data reported to INNS Mapper is free and open access. To find our more please visit the INNS Mapper website here

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