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The importance of transport hubs in stepping-stone invasions
Article first published online: 28 AUG 2008
DOI: 10.1111/j.1365-2664.2008.01540.x
© 2008 The Authors. Journal compilation © 2008 British Ecological Society
Additional Information
How to Cite
Floerl, O., Inglis, G. J., Dey, K. and Smith, A. (2009), The importance of transport hubs in stepping-stone invasions. Journal of Applied Ecology, 46: 37–45. doi: 10.1111/j.1365-2664.2008.01540.x
Publication History
- Issue published online: 14 JAN 2009
- Article first published online: 28 AUG 2008
- Received 4 February 2008; accepted 17 July 2008; Handling Editor: Dan Haydon
Keywords:
- biofouling;
- epidemiology;
- hull fouling;
- invasive species;
- transport networks;
- SIR models;
- spreading rate;
- yachts
Summary
- 1Biological invasions are characterized by occasional long-distance, human-assisted dispersal. Centres of human transportation that are connected by trade to a wide range of other locations (‘transport hubs’) may be important catalysts of the rate at which new populations of an invader are established.
- 2We developed a spatially explicit stochastic model to simulate the spread of a hypothetical marine invader by hull fouling. The model was based on classic ‘Susceptible–Infected–Resistant’ models used in medical epidemiology. It was parameterized using empirical data on the colonization of vessel hulls by fouling organisms, and on maintenance and travel patterns of ~1300 domestic and international yachts around New Zealand. Thirty-six marinas were grouped into three categories that represented a gradient in the number of other transport nodes each marina was ‘connected’ to and the frequencies of yacht movements between them. Invasions were seeded in three locations from each category. Simulations were run over 10 years to determine differences in the trajectory of invasions originating from busy and less frequented transport nodes.
- 3Busy ‘hub’ locations were 75% more likely to become infected by an invader than quieter locations. Infection of hub nodes occurred at an earlier average stage in the invasion sequence. This occurred irrespective of whether the initial source of the invasion was associated with low or high traffic volume and connectivity.
- 4Biotic invasions originating from hub locations did not consistently result in faster spread, or a larger number of secondary infestations. However, the rate of spread from hubs was less variable than from quieter nodes and was less often preceded by a prolonged lag period.
- 5Synthesis and applications. Rapid spread of invasive organisms can occur from busy and from seemingly unimportant transport nodes. Busy locations were consistently more likely to become infested by an invader and to accelerate spread to secondary locations faster. Busy transport hubs should be considered a priority for the allocation of preventative and management efforts, such as regular baseline or target surveys and the development of incursion response plans that minimize the risk of spread within the transport network.