Our ships carry invasive species, not just trade — and it is rapidly getting worse

More maritime traffic means a higher standard of living — but also more invasive species.

Paper ship.

Image via Pixabay.

The rise in global maritime traffic could lead to dramatic increases in the number of invasive species globally over the next 30 years, a new study from McGill University researchers reports. The authors also say that this increase in shipping will come to far outweigh climate change in the spread of non-indigenous pests to new environments in the coming decades.

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“Biological invasions are believed to be a major driver of biodiversity change, and cause billions of dollars in economic damages annually,” says senior author Brian Leung, an associate professor in McGill’s Department of Biology and School of Environment. “Our models show that the emerging global shipping network could yield a three-fold to twenty-fold increase in global marine invasion risk between now and 2050.”

Some 80% of world trade gets ferried around on boats, as do between 60% and 90% of marine invasive species. The latter get onto ships either in ballast water — which is pumped in to help balance the vessels — or attach to their hulls as stowaways. So, the team says that to understand how invasive species will evolve over time, we need to look at how shipping patterns could change.

To that end, the team used socioeconomic-growth scenarios (developed as part of the United Nations’ Intergovernmental Panel on Climate Change, the IPCC) to build several computer models that estimated future rates of global shipping traffic growth. As population and wealth increase in different areas of the globe, the demand for goods and services that aren’t available locally also spikes — leading to more shipping. The models estimated a pretty wide range of increases in bio-invasion risk — from three- to twenty- fold — which the team says comes down to uncertainty in the socioeconomic paths different areas will take in the future.

“Our study suggests that, unless appropriate action is taken, we could anticipate an exponential increase in such invasions, with potentially huge economic and ecological consequences,” says Anthony Sardain, a graduate student in Leung’s lab at McGill and the study’s lead author.

“Despite this large range, all scenarios point to an increase in both shipping and invasions. That should alert us to the gravity of the situation, and the importance of measures to curtail biological invasions.”

Some progress is being made into limiting the spread of invasive species, the team writes, citing major policy initiatives such as the International Ballast Water Management Convention. The Convention entered into force in 2017 and represents the latest global effort to control bio-invasions through measures such as ballast exchange. Leung explains that it’s still too early to gauge the efficacy of this measure globally, but that their work suggests it’s a step “in the right direction.”

The paper “Global forecasts of shipping traffic and biological invasions to 2050” has been published in the journalĀ Nature Sustainability.

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