Getting swamped: Australian swamp stonecrop (Crassula helmsii) in the UK

In January this year, large parts of southern Australia were ablaze with fierce bush fires, while most of the UK was covered in snow. Half a world away from each other, and at one point nearly 40ºC apart, there aren’t too many similarities to be drawn between the two locations. And yet, there is a water weed, Crassula helmsii, that survives happily in both extremes – and in the UK, where it has been introduced, this adaptability is proving extremely problematic.

 Crassula helmsii, also known as Australian swamp stonecrop or New Zealand pygmyweed, is a small semi-aquatic plant in the Crassulaceae family. As its common name implies, this low-growing succulent originates from the antipodes, but was introduced to Britain from Tasmania almost 100 years ago. Initially sold by garden and aquatic centres as an oxygenating plant, by the 1950s it had established in the wild, and from there it has spread to numerous ponds, lakes and waterways throughout the UK.

A mat of Crassula helmsii in flower

Invasive species catch a wave

Over two years have now passed since the Tohoku earthquake rent the seafloor 40 miles off the coast of Japan. The 9.03 magnitude quake – the largest in Japan’s history – triggered a staggeringly destructive tsunami which cost the lives of over 15,000 people.

Aside from the human tragedy of the disaster, the tsunami has had another, quite unexpected, effect: the transport of invasive species across the globe.  Plants and animals from the north-west Pacific are now washing up over 8000 miles away on North American beaches, sparking fears that a wave of ecological invasions could be threatening coastal environments the length of the continent.

How have these organisms managed to travel so far? Such was the force of the tsunami as it tore into docks, boats and buildings on the Japanese coast that an estimated 1.5 million tons of debris was washed out to sea. This was not just the usual plastic waste that pollutes the Pacific Ocean; individual blocks of steel and concrete weighing over 100 tons have been sighted drifting off the coast of Hawaii and North America. Flotsam this large provides a substrate for sedentary coastal life and can shield species from the worst of oceanic conditions. Individual species regularly make similar transits attached to the hulls of boats.

However, what has surprised ecologists in this instance is the number of species that are washing up after 15 months adrift. Whilst whole communities are not turning up on American shores – larger and more mobile animals in particular have long since been washed away – species are certainly arriving en masse in North America. For example, a pier from Misawa port in Japan was harbouring over 100 species when it beached in Oregon in June 2012.

A pier from Misawa port, covered in non-native kelp, that washed up in Oregon in June 2012.
Source: Oregon Parks and Recreation Department

Asian longhorn beetle – A clear case for early eradication

It was confirmed last month that the first population of the forestry pest, the Asian longhorn beetle (ALB), was found in Kent, UK. Forest Research scientists discovered this damaging native of Japan and China infesting around 20 trees, and are now surveying the area to find out the full extent of the infestation. The establishment of this beetle in the UK could be extremely damaging, costing the timber industry millions of pounds, not to mention habitat loss for native species; there is no question that this pest should be eradicated as soon as possible.

Asian long horn beetle. Copyright Kyle Ramirez

The value of costing nature in the fight against invasive species

Increasingly we are seeing the terms ‘ecosystem services’, ‘ecosystem functioning’ and ‘ecosystem processes’ in the media and the scientific literature, to highlight the benefits the natural environment provides to our wellbeing.  Invasive species, from bivalves to balsams, have the potential to impact on ecosystem services, though it is widely accepted that there are gaps in our understanding within this field.

Ecosystem services can be defined as the ecosystem processes that we as humans benefit from and they can be categorised into four groups:

Provisioning: The ecosystem provides products essential for our everyday needs including timber, fuel, food, genetic resources and medicine.

Regulating: We gain from natural services including pollination of wild plants and crops by bees, by rivers and floodplains providing natural flood management, and climatic regulation.

Cultural: We benefit from natural spaces for recreation and social activity.  We find harmony in natural areas that are aesthetically pleasing.

Supporting: These services underpin all of those mentioned above.  Biological diversity promotes stability and a healthy ecosystem, nutrient acquisition and flow through the ecosystem by fungal and invertebrate decomposers, and primary production.

The north American beaver, Castor canadensis has had a catastrophic impact on Chile’s sub-Antarctic forests impacting on provisional services (picture courtesy of http://www.martinezbeavers.org)

Branson pickle

Sir Richard Branson, the billionaire entrepreneur, is reported to have applied for permits to introduce a colony of endangered lemurs to his British Virgin Islands (BVI), Mosquito and Necker. Having “rescued” the island of Mosquito from purchase by a hotel chain in 2007, his intention was to turn his £10 million Caribbean tax haven into an ecological showcase, a luxury hideaway for the mega rich, with plans for Balinese-style, carbon neutral villas whilst “cultivating and supporting the biodiversity, then introducing habitats (such as rainforests) for people who will live in symbiotic form”.

The fanciful whimsy of the rich and famous is nothing new, however this controversial proposal has hit the headlines in BVI because it would appear that Branson has been granted import permits by the Natural Resources and Labour Minister, Hon. Omar Hodge, against the recommendations of technical groups in the Agriculture and Conservation sectors and in contravention of Territory laws. The decision is being contested by the Ninth district elections contender, Lorie Rymer and a petition is reported to be in circulation and will later be submitted to the Governor Boyd McClearly, who is appointed by the Queen and exercises executive authority on her behalf. Meanwhile, Minister Hodge is standing firm but has apparently alienated members of the community by stating on local radio that he “doesn’t have to answer to anyone because he is the Minister”.

(Ring-tailed lemurs by Woodlouse, Flickr Creative Commons)

The economic impact of invasive species on Great Britain revealed

A report, written by CABI for the Scottish government, Defra and the Welsh Assembly Government, estimates the cost of invasive non-native species to Great Britain in unprecedented detail. Invasive non-native species can have wide-ranging effects on biodiversity, crop production and people’s livelihoods. A better understanding of the negative impacts of invasive species will help to make people aware of invasive non-native species, to prevent new introductions and to deal with the problems caused by established invasive species.

Our rivers – corridors for colonisation

Our river systems are undoubtedly one of the most diverse habitats found within the British Isles.  They provide us with numerous benefits including areas for relaxation and recreation, they harbour high levels of biological diversity, act as natural flood management, provide water for consumption and irrigation, and act as corridors for the movement of nutrients and species in an otherwise fragmented landscape.  However, our river systems are highly vulnerable habitats.  Seasonal variations in hydrological processes render riparian habitats prone to high levels of disturbance which aid the invasion and colonisation of invasive plant species.

Himalayan balsam monoculture on the banks of the River Torridge, North Devon, UK (CABI)

Argentine Ant Invasion Meets Resistance from Natives

The Argentine ant (Linepithema humile), from humble beginnings in South America, is now invasive on every continent and has a place on the list of 100 of the World’s Worst Invasive Alien Species. Transported around the world via human activity, this omnivorous ant impacts upon native flora and fauna and has been incredibly successful in outcompeting and displacing native ants. A recent study indicates, however, that at least one species may be ready to make a stand against the onslaught of the Argentine ant.

An Argentine ant queen and worker (Source: Alex Wild)