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

Rusty Solutions for a Prickly Problem

The state of Queensland has got an alien thorny invader: Prickly acacia, or in scientific terms Acacia nilotica subspecies nilotica.

Prickly acacia invasion, north Queensland, Australia, Photo: Kunjithapatham Dhileepan, DEEDI, Australia

Prickly acacia is a shrub or small tree which belongs to the plant family Leguminosae, subfamily Mimosoideae, a family which also accommodates the sensitive plant Mimosa pudica, well-known as a curiosity house plant. The prickly invader A. nilotica is native to Africa, the Middle East and the Indian subcontinent and was introduced from India into Australia in the late 1890s. Originally imported as an ornamental, A. nilotica ssp. indica was later widely used as a shade and fodder tree for sheep. But what was initially a valued addition to the Australian flora soon became a menace. When the grazing regime in Australia changed from predominantly sheep to cows and the country also experienced a number of successive wet years, the balance swung in the favour of prickly acacia. The thorny shrub spread quickly and has now invaded around six million hectares of arid and semi-arid land in the State of Queensland. Acacia nilotica ssp. indica is also present in the Northern Territory as well as in Western Australia. Due to its substantial impact on the environment as well as on the economy, particularly on the livestock industry, prickly acacia was initially declared a noxious weed in Queensland in 1957. Subsequently the plant has also been listed as a “Weed of National Significance” for the whole of Australia. And Australians have every reason to be worried, as the prickly invader has got the potential to spread throughout the arid regions of the whole of northern Australia.

Alien Battlefield

Recent articles in Science, the NY Times and Nature have suggested that we should embrace invasive species and the resultant “novel ecosystems” and that those that do battle with such species are verging on xenophobic. This is a common cycle in many fields and I’m told that a discussion thread is considered closed once a poster has been described as xeonophobic or worse, if so this discussion could be over before it even begins. Nevertheless, a group of scientists and practitioners wrote a response which can be found on the ISSG website. The issues are certainly complex. It is true that preserving pristine ecosystems is a lost goal and there are probably none in existence anymore, but to do nothing and indeed to try to argue that the new system is one worth accepting suggests that the authors have either given up in the face of too difficult a task, or have seen an opportunity to publish something controversial. There are certainly “profits” of doom to be had on both sides. In order to get your invasive management project funded it is necessary to take the public with you and when engaging with the media evocative negative language can appear in print. On the other side it is easier to stand out from fellow authors if you challenge an accepted paradigm. In the case of weeds, it is generally understood that monocultures of the new plant are less biodiverse but more productive than the flora they replace and depending on your priorities their arrival could be a good or a bad thing. If we accept that biodiversity is a priority there are few arguments to be had for introducing new invasive exotic species except for biocontrol where the excellent paper by Van Driesche and many co-authors shows the potential benefits. It is this tool that was notably overlooked in the discussions despite choosing the Galapagos as a case study where there are excellent targets for weed biocontrol yet no funding has materialised despite the vast sums spent on vertebrate eradications.

Lantana on the Galápagos - a major invasive for which all hope is not lost

The Nagoya protocol and biological control by Matthew Cock

Since 2009, I have worked with the Global Commission on Biological Control and Access & Benefit Sharing of the International Organisation for Biological Control to raise awareness of the issues relating to biological control which may be affected under the Convention on Biological Diversity’s access and benefit sharing protocol which was finally agreed at COP10 in Nagoya, Japan, in October last year¹.

The IOBC Commission attended various background meetings, produced a report for the Global Commission on Genetic Resources for Food and Agriculture², followed by a Forum Paper in the journal BioControl³ and various news items culminating in a World View page in Nature⁴ the month before the Nagoya meeting. Basically, we put the case that biological control is a public good, that countries that supply biological control agents are also importers of biological control agents, that the best way forward would be to continue the 100+ years history of free multi-lateral exchange of biological control agents between countries as non-commercial research under any future access and benefit sharing protocol, and that benefit-sharing should be based on shared research activities.

About the CABI Invasives blog

The CABI Invasives blog is an opportunity for scientists across our centres to highlight their research and debate topical issues in the field of invasive species.  We hope the blog will reflect the diversity of research projects and consultancies CABI scientists are involved in and can be used to spark wider debate in the field of invasives, whist ultimately working towards the reduction in occurrence and impact of invasive species across the globe through awareness raising and dissemination of scientific information and experiences.

CABI and invasive species

CABI is a not-for-profit science-based development and information organization. We improve people’s lives by providing information and applying scientific expertise to solve problems in agriculture and the environment. CABI has been working on sustainable solutions for the management of invasive species for almost 100 years. World-wide we research and implement biological control programmes against invasive plants, animals and microorganisms which cause an adverse detrimental effect in their areas of introduction.  We also study the impact of invasive species on the habitats they invade, advise on invasive species policy and produce books and tools for environmental managers, researchers and farmers.