Biological invasion warning for ships waiting in the Strait of Hormuz: 'Could lead to an ecological crisis'

An international team of marine biologists has warned that the closure of the Strait of Hormuz could threaten not only the flow of energy and trade but also marine ecosystems. According to an article published in the journal Biological Invasions, ships remaining stationary in the region for months could become "carriers" for invasive marine species.

Researchers state that an estimated 1,500 ships have been stranded in the Persian Gulf since February, with hundreds more waiting in the Gulf of Oman. The long periods that ships remain stationary increase the risk of "biofouling," which leads to marine microbes, algae, and invertebrates attaching themselves to hulls and multiplying.

Risk could grow when ships set sail again

The lead author of the study, marine ecologist Prof. Mario Tamburri from the University of Maryland in the US, said that ships waiting in this manner is the "worst-case scenario" for the spread of invasive species. Tamburri explained that new, hard surfaces placed in the sea are first covered with microbes and bacteria, and then algae spores and larvae of mussels, worms, and similar invertebrates form colonies on these surfaces.

According to scientists, because the seabed of the Gulf consists mostly of mud, silt, and sand, hard surfaces are limited. For this reason, ship hulls provide a suitable foundation for organisms looking for a place to attach in the region. It is stated that under normal conditions, ships stay in port for one to three days, but invasive species can accumulate rapidly on ships after 10 days.

The article emphasized that due to the central role of the Strait of Hormuz in global shipping, the risk may not be limited to the region alone. If the waiting ships move to different ports, the species attached to their hulls could be transported to very distant ecosystems.

Warning of economic and ecological damage

Researchers state that invasive species can suppress native organisms, lead to the extinction of some local species, and affect fishing and aquaculture. Among the warnings is that these species could cause blockages in critical infrastructure such as the cooling systems of power plants.

Biofouling also means additional costs for ships. According to Tamburri, even a biofilm layer forming on the hull can increase fuel consumption by 2 to 5 percent. In cases of heavy accumulation such as mussels and barnacles, this rate can rise up to 25 percent.

The International Maritime Organization recommended in 2023 that ships that have been idle for a long time should take measures to remove biofouling before setting sail again. However, researchers assess that it would be logistically difficult to clean the large number of large ships in the Gulf comprehensively before they move.

According to scientists, international cooperation is therefore of critical importance. It is stated that ports that will accept ships from the region should increase their cleaning and inspection capacity when the ships arrive. The article noted that ports such as Jeddah, Mumbai, Colombo, Singapore, Alexandria, Piraeus, Algeciras, and Rotterdam are among the points at risk.

Tamburri stated that there is a strong expectation that non-native organisms will be transported once the strait reopens, and expressed that whether the event turns into a global "biological invasion super-spread" depends on subsequent international measures.