Shipping traffic globally could increase invasive species

Mohammed El-Said
6 Min Read

One of the key questions is how will environmental drivers change over time? While we have good estimates for drivers such as climate change, far less is known about biological invasions.

A recent study by McGill University researchers revealed that rising global maritime traffic could lead to sharp increases in invasive species around the world over the next 30 years.

Findings of the study which appeared on Monday in the Nature Sustainability journal, suggested that shipping growth will far outweigh climate change in spreading non-indigenous pests to new environments in the coming decades.

Previous studies have often focused on the socio-cultural impact of invasive species on indigenous peoples, rather than considering their knowledge, scientific research, and ongoing initiatives to address invasive species and environmental change, more widely.

The study is considered to be the first estimate of global shipping traffic change over time, and the consequences it could have on biological invasions. Other work in invasion ecology has modelled shipping traffic as constant, despite all historical evidence being to the contrary.

In the study, researchers have shown that forecasts for biological invasions could be underestimated by an order of magnitude through not considering the changes in human vectors of transport (i.e. shipping).

“This work is broadly integrative, synthesising data and research across disciplines, including maritime traffic, socioeconomic indicators, quantitative projections of global development and climate change, and invasion models” Anthony Sardain, the researcher at McGill University, and correspondent author of the study, told Daily News Egypt.

Foreseeing impact  

Regarding the importance of the study, Sardain said that it gains its significance from two reasons. First, biological invasions are relevant since they are believed to be one of the major drivers of biodiversity change and cause economic damage costing billions annually. It is a major unanswered question of how they will change in the future.

“Our study finds that, unless appropriate action is taken, we could anticipate an exponential increase in such invasions, which, conceivably, could have unprecedented economic and ecological consequences,” he stated.

“The question of forecasting biological invasions is one which the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) is interested in answering,” Sardain added.

The IPBES is the biodiversity equivalent to the International Panel on Climate Change (IPCC).

He noted that human vectors of transport are important, since humans are the primary means by which non-indigenous species are moved around the world. Shipping accounts for 80% of world trade, and about 60-90% of marine bio-invasions.

To understand how invasions will change, we need to understand how human movement patterns could change.

For main conclusions of the paper, the researchers expected global maritime traffic to increase from 240% to 1,209% by 2050, compared with 2014 levels. Integrating their predictions with global climate change projections and shipping-mediated invasion models, the researchers forecast invasion risks to surge in middle-income countries, particularly in northeast Asia.

They also discovered that shipping growth will have a far greater effect on marine invasions than climate-driven environmental changes, while climate change might actually decrease the average probability of invasion, and the emerging global shipping network (GSN) could then yield a three to 20-fold increase in global invasion risk.


In order to reach their findings, the researchers used various statistical methods. “Namely, we developed a novel model of global shipping traffic, which we combined with published models of biological invasions and global economic development scenarios prepared as part of the IPCC to derive projections of biological invasions to 2050,” the researcher said.   

He added that the team of researchers began working on this particular study in 2014.

Sardain explained further that invasive species have largely ecological and economic damages. The study concerned all marine species that are predisposed to be transported via shipping traffic, either through ships’ hull fouling or through ballast water release.

According to the paper, particularly damaging examples of worldwide species which have been spread through these channels include: the zebra mussel Dreissena polymorpha and the Asian clam Potamocorbula amurensis in the US, the comb jelly Mnemiopsis leidyi in the Black and Azov Seas, and the toxic dinoflagellate Gymnodinium catenatum and the northern Pacific sea star Asterias amurensis in Australia

Most affected regions

According to the study, the greatest transfer of invasive species will occur along connections with the highest shipping traffic. The researchers detected that connections with middle income economies, in particular northeast Asia, will likely see the greatest increase.

Connections with large, developed economies, e.g. around the Mediterranean, or fast-growing, but less-developed economies – African and Southern South America – will experience more moderate increases.

Meanwhile, smaller, slow-growing economies, such as those in the eastern Indo-Pacific region, will remain relatively low-traffic – and thus experience fewer invasions – all the way through to 2050.

“Science is a stepwise endeavour, and as such we will continue to work on, extend, and improve our model. We will continue to refine our model, for instance looking at within-regional traffic, as well as other environmental consequences of shipping beyond invasive species,” Sardain said.

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Mohammed El-Said is the Science Editor for the Daily News Egypt with over 8 years of experience as a journalist. His work appeared in the Science Magazine, Nature Middle East, Scientific American Arabic Edition, SciDev and other regional and international media outlets. El-Said graduated with a bachelor's degree and MSc in Human Geography, and he is a PhD candidate in Human Geography at Cairo University. He also had a diploma in media translation from the American University in Cairo.
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