Biological Invaders: can we predict their ecological impacts?

Invasions by animals and plants cause enormous ecological and economic harm, much of this because invasive species impact on native flora and fauna, even driving local species to extinction. A holy grail of invasion biology is to discover general rules that can help us predict which species will invade and their likely ecological impacts. I have been working on one such general rule: the relationship between resource use and resource abundance (often called the ‘functional response’ of a species towards, for example, its prey). I have evidence that the most damaging invaders may have much greater functional responses than comparator native species. For example, the bloody red shrimp from the Ponto-Caspian region of Eastern Europe, now invading Western Europe including the British Isles, devours prey such as water fleas at over twenty times the rate of native shrimps. Further, this corresponds with the known damaging impact of the invader on local zooplankton communities.

DICK shrimp jpg

The invasive and highly predatory ‘killer shrimp’, Dikerogammarus villosus, is a global threat to the biodiversity of freshwaters, but recent progress in predicting invasive species impacts mean that we are better able to tackle such emerging threats.

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Dr Mhairi Alexander and Professors Jaimie Dick, Tony Ricciardi and Hugh MacIsaac on field work in Africa following their workshop on invasive species; Dr Alexander subsequently received a post-doctoral Fellowship to work in the Centre for Invasion Biology, Stellenbosch University.

Through my Leverhulme Study Abroad Fellowship, I am addressing the question as to whether this is a general rule for many invaders and thus if the rule can be applied predictively—that is, if we measure the functional responses of emerging, new and potential invaders, can we spot the ones that are most likely to be damaging and focus resources on stopping them? South Africa is an ideal location to set up new projects to address this question, as this region has received hundreds of animal and thousands of plant invaders. I have thus visited the Centre for Invasion Biology (CIB) at Stellenbosch University, near Cape Town, whose Director, Professor David Richardson, hosted me and one of my PhD students, Mhairi Alexander, from July to October 2012 and again in 2013.

My research sparked interest from many leading invasion ecologists, and we organised a workshop in Stellenbosch on risk assessments in biological invasions. While in Stellenbosch, we also successfully applied for a two-year postdoctoral fellowship from the CIB, for Mhairi to test our ideas over a range of invasive species in South Africa, including marine mussels damaging coastal communities, and wasps threatening the wine industry through predation on pollinators.

We have published our ideas in Biology Letters and Biological Invasions and have a manuscript in preparation that sets out a framework for research in the field that one day might allow us to predict, and thus prevent, future damaging biological invasions.

Professor Jaimie TA Dick
Queen’s University Belfast