The risk of marine bioinvasion caused by global shipping
Published in Ecology Letters, 2013
By H. Seebens, M. T. Gastner and B. Blasius
The rate of biological invasions has strongly increased during the last decades, mostly due to the accelerated spread of species by increasing global trade and transport. Here, we combine the network of global cargo ship movements with port environmental conditions and biogeography to quantify the probability of new primary invasions through the release of ballast water.
We find that invasion risks vary widely between coastal ecosystems and classify marine ecoregions according to their total invasion risk and the diversity of their invasion sources.
Thereby, we identify high-risk invasion routes, hot spots of bioinvasion and major source regions from which bioinvasion is likely to occur. Our predictions agree with observations in the field and reveal that the invasion probability is highest for intermediate geographic distances between donor and recipient ports. Our findings suggest that network-based invasion models may serve as a basis for the development of effective, targeted bioinvasion management strategies.
The ability to forecast locations at the greatest risk of new invasions remains one of the main challenges confronting invasion biologists (Mack et al., 2000; Kolar & Lodge, 2001).
Among the uncertainties are the lack of detailed information about ballast water releases on a global scale, the relevance and implementation of biotic interactions and the likelihood that an established species poses negative impacts in the recipient ecosystem.
Our study highlights that a forecast of invasions can only be achieved by combining information concerning ballast water transport, environmental heterogeneity and biogeographic distributions.
Our vector-based modelling approach provides new avenues in this direction; it allows predicting expected shifts in invasion risks caused by global climate change (e.g. rising water temperature), changing trading patterns or new shipping routes (e.g. opening of Arctic passages), new ballast water management options (e.g. ’mid-ocean-exchange’) and it may serve as a basis for the establishment of effective and targeted mitigation programs.
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