More than 1,500 cargo ships are currently stuck in the Persian Gulf and Gulf of Oman, many of them having languished for more than 100 days awaiting passage through the blocked Strait of Hormuz. According to a July 22 study published in Biological Invasions, the stalled ships could be ground zero for an invasive species “super-spreader” event.
Under typical conditions, ships in the Gulf Region linger for one to three days on average before passing through the Strait of Hormuz, according to the study. In that amount of time, it’s hard for organisms to attach to the boat in meaningful numbers—a process called biofouling. But after just 10 days, biofouling can reach the rapid growth phase, and after 18 to 30 days the International Maritime Organization (IMO) recommends idle boats take action to manage biofouling before departing from ports to reduce the spread of non-native species globally.
According to the researchers, “the connection between immobile biofouled ships and marine species invasions has long been recognized.” In WWII New Zealand ships being held in English ports while awaiting convoy escorts were responsible for the spread of the invasive Australasian barnacle Austrominius modestus to western Europe, for example.
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With the unprecedented hold-up in the Gulf Region, now researchers worry there could be an equally unprecedented global bioinvasion event once the ships inevitably continue on their journeys—unless proper action is taken.
Sarah Bailey, an assistant professor with the University of Toronto’s Department of Physical and Environmental Sciences, says Canada stands to see a number of these foreign species reach coastal ports if the researchers’ warning comes to fruition. Among them are species of algae, barnacles, mussels, small shrimp, and tunicates. “Basically anything that lives on underwater surfaces—anything you’d see living on a dock—can get moved by these ships.”
In the Maritimes, several invasive species of tunicates, also known as sea squirts, have been straining aquaculture industries in the region for decades. “They foul buoys and nets and it makes the equipment really heavy causing it to sink,” says Bailey. “So the shellfish harvest is impacted, and they have trouble selling the product because it gets contaminated with these non-native species.”
Exactly which invasive species could end up on Canadian shores is hard to predict, due to the Gulf Region being a central node for an expansive global shipping network. “So not only is it the species native to the Arabian Sea that could get moved from ships that are stuck in that location,” says Bailey. “But those ships could already have been fouled with species from other parts of the world.”
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In Canada, the regions most likely to be impacted would be saltwater shipping hubs in more temperate regions such as Vancouver and Halifax. “The Arabian Sea’s average annual temperature is quite high, at about 28 degrees,” says Bailey. “But it drops seasonally to 15 or 20 degrees. So I think there’s a chance that things that can survive there could also survive here, depending on location.”
To prevent a “super-spreader” event like the one predicted by the study’s authors, Bailey says ship owners should be diligent about cleaning their hulls before leaving the port. But the study’s lead author, Mario Tamburri, told the CBC this is unlikely to happen as there are simply too many hulls for ship-cleaning companies to handle and workers would face serious safety risks due to the conflict.
As of now, the IMOs guidelines for dealing with biofouling are not mandatory, which Bailey says she’s hopeful will change in the near future. “Canada is working with various members of the IMO, and we are currently drafting new regulations for management of ship biofouling, including keeping your ship clean, using coatings that prevent biofouling in the first place, and using cleaning technologies that prevent the organisms from being released back in the same location.”
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