The Strait of Hormuz, a critical maritime chokepoint, has been at the center of geopolitical tensions since the outbreak of war with Iran in February. The intermittent blockage of tanker traffic through this vital waterway, which facilitates approximately 20% of the world’s oil supply, has raised concerns beyond just economic disruptions. Scientists are now warning of a potential ecological catastrophe fueled by the stagnation of ships, which could become vectors for invasive species.
According to a study published in the journal Biological Invasions prolonged stationary periods of ships can lead to substantial biofouling where microorganisms, algae, plants, and invertebrates accumulate on the hulls. This buildup can then be transported to various ecosystems around the world as the vessels resume their journeys, potentially causing irreversible damage.
Biofouling and the spread of invasive species
The study highlights that once invasive species take hold in a foreign ecosystem, they are nearly impossible to eradicate. Mario Tamburri, a marine ecologist at the University of Maryland’s Center for Environmental Science and lead author of the study, emphasizes the severe impact these organisms can have on commercial operations like aquaculture and fisheries, as well as the broader environment.
One stark example is the zebra mussels in the Great Lakes. Native to the Caspian and Black Seas, these invasive species quickly spread in the 1980s and are now present in the Mississippi and St. Croix Rivers, as well as the West Coast. Ecologists have been battling this invasive species for 50 years, with little success in removing them once established.
The role of anti-fouling measures and their limitations
Ships are typically coated with anti-fouling paint which contains chemicals designed to prevent marine animals from adhering to or growing on them. However, when ships remain stationary for extended periods, these coatings become less effective, allowing for extensive growth of biofoul. This issue was particularly evident during the COVID-19 pandemic when many ships were stalled for long periods, leading to significant biofouling.
Currently, the Strait of Hormuz is experiencing severe disruptions, with more than 1,500 ships idle in the Persian Gulf and hundreds more anchored in the Gulf of Oman. The unique ecological system of the region, characterized by high salinity and warm temperatures, exacerbates the risk of a superspreader event. The marine organisms in this area are particularly hardy and robust, increasing the likelihood that they can spread and survive in other environments.
Preventive measures and future regulations
The combination of extensive biofouling growth, species accumulation, and the global reach of affected vessels has created an immense international biosecurity threat. To mitigate this risk, Tamburri recommends preventive measures such as cleaning ship hulls before they leave port. Many shipping ports already offer in-water cleaning services, where divers scrape off the biofoul. However, ecologists suggest using a vacuum-like device to avoid putting live organisms back into the water, only to attach to another ship.
In the future, more regulations may be established to turn away ships that are too heavily fouled. Currently, all vessels entering New Zealand waters are required to have a clean hull to reduce the risk of biofouling pests. The International Maritime Organization is also pushing to strengthen biofouling regulations to prevent the spread of invasive species.
