Invasive Biofilm Threatens as Ships Idle Near the Strait of Hormuz: Assessing and Addressing the Problem

 

 

     A phenomenon known as biofouling, or growths of biofilm on ships composed of microorganisms, algae, and even plants and invertebrates, can be transported around the world. Long, stationary periods for ships often involve a substantial buildup of this biofilm. The issue is known as biofouling.

“The biofilm grows on the side of the commercial ships and then gets transported around the world as the vessels travel from port to port, Mario Tamburri, a marine ecologist at the University of Maryland's Center for Environmental Science and lead author of the study, told ABC News.”

"We know that these invading invading organisms can cause millions of dollars' worth of damage and impact -- commercial operations like aquaculture and fisheries -- and change the environment," Tamburri said.

     He also cited as an example the invasive zebra mussel in the Great Lakes. I know when I lived near Lake Erie in Buffalo, New York, in 1991, the local tap water tasted really bad, and people said it was from the zebra mussels, and everyone had alternate sources of water for drinking. Those zebra mussels are native to the Caspian and Black Seas south of Russia and Ukraine. They began spreading in the Great Lakes in the 1980s and have since moved to the Mississippi and St. Croix Rivers, and even due to human transport, to the West Coast.   

“Ships are typically coated with an "anti-fouling" paint, formulated with chemicals to prevent marine animals from adhering to or growing on them, Tamburri said.

“But when ships sit around for a long time, the coatings no longer work well, allowing for the possibility of "extensive growth." During the COVID-19 pandemic, many ships around the world were stalled for long periods of time, allowing for that kind of growth, Tamburri added.

     A paper on the biofilm threat was published in the journal Biological Invasions. It notes that more than 1,500 ships remain idle in the Persian Gulf and hundreds more are anchored in the Gulf of Oman, and although that may no longer be the case, there are still plenty of ships anchored near there. 

     There is legitimate concern about a superspreader event as Tamburri details below:

“The types of organisms that live in the region's unique ecological system also exacerbate the risk of a superspreader event, Tamburri said.

“The marine organisms that live within the Strait of Hormuz are especially "hardy" and "robust" because they have adapted to high salinity and warm temperatures, which increases the likelihood that they can spread and survive in other environments, Tamburri said.

"If you can survive high temperatures, high salinities, you can probably survive long ship voyages," he said.

     The warm, nutrient-rich waters of the Persian Gulf allow many of the species to grow and reproduce significantly when a suitable substrate, such as ships hulls, becomes available. In addition, he notes, it is happening in summer when the water is warmer. This, in addition to the vast international reach of the ships, could be a recipe for a worst-case scenario = a superspreader event of multiple invasive species.

"All these marine organisms, invertebrates like barnacles and mussels and algae -- they start growing and reproducing," he said. "They start growing and reproducing, and they're sitting in this warm soup of nutrient-rich water."

“In addition, stressed ecosystems, such as industrial ports, are highly vulnerable to bioinvasion because disturbances allow for fast-growing opportunistic species to establish themselves, the paper states.”

     These kinds of biological invasions are difficult and expensive to remediate. Thus, prevention and early detection are emphasized. Ship hull cleaning, which is often done at ports, is one method of addressing the problem.

“Many shipping ports have in-water cleaning services, in which divers scrape off the biofoul to remove the material. Ecologists recommend taking it a step further, and having the divers use a vacuum-like device as well to avoid putting the live organisms back into the water, only to attach to another ship.”

     Recommendations from the paper are given below:

     Biofouling regulations are on the horizon. New Zealand currently requires ships to have clean hulls before docking at its ports. The International Maritime Organization is working to update its biofouling regulations.

     The paper compared invasive species spreading to the spreading of infectious diseases, noting that epidemiological approaches used for those diseases can be effective in assessing and addressing biofouling. The problem is basically a marine biosecurity problem.

 

 

 

References:

 

Superspreader event of invasive species originating near Strait of Hormuz possible. Julia Jacobo. ABC News. July 25, 2026. Scientists warn of possible invasive species superspreader event due to stalling near Strait of Hormuz - ABC News

Closure of the Strait of Hormuz may trigger a bioinvasion super-spreader event. Mario N. Tamburri, James T. Carlton, April M. H. Blakeslee, Alejandro Bortolus, João Canning-Clode, Susana Carvalho, Andrew L. Chang, Ian C. Davidson, Sarah C. Donelan, Lisa A. Drake, Amy E. Fowler, Amy L. Freestone, Linsey E. Haram, Chad L. Hewitt, A. Whitman Miller, Jim R. Muirhead, Okko Outinen, Tamara B. Robinson, Gregory M. Ruiz, Christopher Scianni, Evangelina Schwindt, Carolyn K. Tepolt, Thomas W. Therriault & Bella S. Galil. Brief Report. Biological Invasions. Volume 28, article number 177. July 22, 2026. Closure of the Strait of Hormuz may trigger a bioinvasion super-spreader event | Biological Invasions | Springer Nature Link