Stranded Hormuz ships risk global biological invasions, study warns

More than 1,500 large commercial vessels stranded in the Strait of Hormuz following its closure on February 28 could trigger a global wave of biological invasions, researchers have warned. A study published in Biological Invasions highlights that marine organisms accumulating on ship hulls during extended stationary periods may be transported to ports worldwide once traffic resumes, potentially creating a "super-spreader" effect for invasive species.

Perfect storm for biofouling

Professor Mario Tamburri of the University of Maryland, the study's lead author, described the current situation as a "worst-case scenario" compared to previous shipping disruptions. The risk is amplified by several converging factors: the unprecedented number and size of stranded vessels, combined with the fact that the closure coincides with spring and summer—peak seasons for marine organism growth and reproduction. Organisms native to the Gulf, already adapted to extreme temperatures and high salinity, may prove particularly resilient when introduced to new environments.

Critical ports at highest risk

The study identifies specific ports facing elevated invasion risks due to short voyage times and similar environmental conditions. Jeddah, Mumbai, Colombo, Singapore, Alexandria, Piraeus, Algeciras, and Rotterdam are highlighted as particularly vulnerable first destinations. The Asian green mussel, native to the Gulf, serves as a cautionary example—having already established itself in Florida, the Caribbean, Australia, and South America, where it competes with native species and clogs industrial infrastructure.

Urgent call for international action

Researchers warn that the international maritime community remains ill-prepared for this biosecurity threat. While regulations are being developed through the International Maritime Organization (IMO), they will take years to finalize. The study recommends implementing early-warning and rapid-response systems at first ports of call, alongside coordinated international efforts bridging biological invasion science, maritime logistics, and regulation.