Idle ships could spread invasive species worldwide once Hormuz reopens

The economic consequences of a prolonged closure of the Strait of Hormuz have been widely discussed, yet the potential ecological damage caused by thousands of ships remaining idle during a lengthy blockade has so far received far less attention.

Research by an international team of ecology scientists has found that more than 1,500 commercial vessels that have been laid up in the Persian Gulf since February could pose a significant environmental threat, as highlighted in a feature on The Conversation outlet.

According to their findings, marine organisms have been accumulating on their hulls. As the strait reopens, the vessels could carry these organisms to ports around the world, potentially triggering an international marine biosecurity “super-spreader” event.

The introduction of alien marine plants, animals, parasites and diseases can disrupt native ecosystems and wild fisheries, while also threatening aquaculture stocks and coastal industries. Such invasions can result in substantial environmental damage and economic losses.

The closure of the Strait of Hormuz, however, is not the first instance in which disruptions to maritime traffic have led to significant biofouling on vessels left idle for extended periods.

Researchers have identified 24 major choke points in global maritime trade. Twenty of them have alternative routes, allowing ships to be rerouted when disruptions occur. Although such diversions can take longer and increase costs, they can help prevent large numbers of vessels from remaining stationary for prolonged periods.

Only four of the identified choke points have no alternative routes: the Strait of Hormuz, the Oresund Strait in the Baltic Sea, the Bosporus and Dardanelles straits leading from the Black Sea, and the Bohai Strait in the Bohai Sea.

Disruptions at these strategic waterways can result from conflicts and wars, but shipping routes can also be deliberately or unintentionally disrupted for other reasons, including economic oversupply, seasonal market conditions, vessel maintenance or infrastructure upgrades.

Stationary vessels can accumulate substantial amounts of biofouling within a relatively short period, particularly in tropical waters. When the ships eventually resume their journeys, they can transport those organisms to new regions, potentially introducing invasive animals and plants, as well as parasites and diseases.

According to the researchers, the Persian Gulf is already home to more than 50 marine non-native species, while many species native to the region have been introduced elsewhere around the world. Managing biofouling on commercial vessels that make short port visits remains a major challenge.

The researchers warn that mitigating the potential impact of this marine “super-spreader” event, as well as similar incidents in the future, will require international cooperation and coordinated action to protect ecosystems, economies and communities from marine biological invasions and their consequences.

By Nazrin Sadigova