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A novel approach for predicting the impacts of invasive species

Invasive animals and plants often cause substantial environmental and economic damage to ecosystems. Increased rates of biological invasions worldwide is leading to growing pressure to prioritise and alleviate such events, a process that must be balanced against perceived impacts on invaded communities. Management must be cost-effective, with allocation of resources towards this goal requiring accurate and reliable predictions of invasive species impacts. To date, however, there has been a lack of common methodologies across taxonomic and trophic groups for the prediction of the ecological impacts of invasive species.

A paper led by C·I·B collaborator Prof. Jaimie Dick from Queen’s University Belfast (QUB), together with C·I·B staff and postdoctoral fellows, and collaborators from other international institutions worldwide, provides an exciting new framework on how such predictions can be made. This work has just appeared in the journal Biological Invasions. The concepts and ideas follow discussions that were developed at a risk assessment workshop run by the C·I·B in August 2012, and centre around the realisation that ecologically damaging invaders are generally characterised by more efficient resource use. A prediction of invader impact can be made by quantifying the relationship between resource use and availability of the resource (“functional response”) and the functional response between the invader and a similar native species are compared. Indeed, recent studies of invasive crustaceans, such as the ‘killer’ and ‘bloody red’ shrimps support such a predictive capacity.

A further challenge in invasion ecology is the testing of major hypotheses, such as ‘enemy release’ and ‘biotic resistance’. The authors demonstrate how the application of comparative functional responses can allow the formulation and testing of such hypotheses. For example, the team has shown that, parasites can actually increase the impacts of their invasive hosts, counter to perceived knowledge.

Although there are challenges regarding how to use this framework in applied methodologies, the integration of numerical responses, multiple predators effects and trait-mediated interactions will allow the further development of such a prediction tool. The paper also highlights the need for further case studies to allow an overall test of the framework by meta-analysis, and work at the C·I·B headed by post-doctoral fellow Dr Mhairi Alexander is currently underway with a range of invasive animals and plants in South Africa.

Ponto-Caspian freshwater ‘bloody red’ shrimp

The predatory Ponto-Caspian freshwater ‘bloody red’ shrimp, Hemimysis anomala, is a recent and ecologically damaging invader in Europe and North America.

The invasive species in Europe, the ‘Killer shrimp’, Dikerogammarus villosus

Comparisons of functional responses of the emerging invasive species in Europe, the ‘Killer shrimp’, Dikerogammarus villosus, with native amphipod species showed great feeding rates by the invader on a range of prey species.

 




Read the paper:

Dick, J.T.A., Alexander, M.E., Jeschke, J., Ricciardi, A., MacIsaac, H.J., Robinson, T.B., Kumschick, S., Weyl, O.L.F., Dunn, A.M., Hatcher, M.J., Paterson, R.A., Farnsworth, K.D. and Richardson, D.M. 2013. Advancing impact prediction and hypothesis testing in invasion ecology using a comparative functional response approach. Biological Invasions (DOI 10.1007/s10530-013-0550-8)

For more information, contact Dr Mhairi Alexander at malexander@sun.ac.za