Scientists warn of possible invasive species superspreader event due to stalling near Strait of Hormuz - ABC News

Scientists warn of possible invasive species superspreader event due to stalling near Strait of Hormuz<br>Over 1,500 ships are idle in the Persian Gulf, hundreds more in Gulf of Oman.

ByJulia Jacobo<br>July 25, 2026, 11:22 AM

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In this picture obtained from Iran's ISNA news agency on June 18, 2026, vessels are seen anchored in Bandar Abbas along the Strait of Hormuz.<br>Amirhossein Khorgooei/ISNAvia AFP via Getty Images, FILE

A possible ecological catastrophe could be fueled by stalled ships as conflict over the Strait of Hormuz continues to block traffic on the passageway, scientists say.<br>The Strait of Hormuz has been a major source of contention since the war with Iran broke out in February. In retaliation to the ongoing conflict, Iran has intermittently caused a decline of tanker traffic through the critical waterway, which connects the Persian Gulf with the Gulf of Oman for the passage of around 20% of the world's oil supply, according to the U.S. Energy Information Administration.

In this May 6, 2026, file photo, a cargo ship is docked at the Port of Fujairah, in Fujairah, United Arab Emirates.<br>Amr Alfiky/Reuters, FILE

But continued closures at the Strait of Hormuz could trigger a super-spreader event of invasive species as marine organisms attach to the idle vessels and get transported to other ecosystems around the world, according to a paper published Wednesday in the journal Biological Invasions.<br>This is because prolonged stationary periods can lead to substantial biofouling on ships, according to the paper. Buildup can include microorganisms, algae, plants and invertebrates.

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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.

Once invasive species take hold of a foreign ecosystem, it's nearly impossible to get rid of them, Tamburri said.<br>"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.

The full shipping network consists of 3,027 unique ships, making 248,362 calls to 3,517 unique ports and anchorages. a is the connectivity of global source–destination port pairs for commercial shipping traffic after ships leave the Gulf region starting February 27, 2025, indicating common global reach in one month after departure. b is the connectivity of global source–destination port pairs for commercial shipping traffic starting February 27, 2025, after ships leave the Gulf region, indicating potential global reach in one year after departure.<br>as presented in Tamburri et al., Biological Invasions 28, 177 (2026).

One example is the zebra mussels in the Great Lakes, Tamburri said. Native to the Caspian and Black Seas south of Russia and Ukraine, zebra mussels quickly spread in the Great Lakes in the 1980s and are now present in the Mississippi and St. Croix Rivers, according to the National Park Service. They have also now spread to the West Coast due to human transport.<br>There is little to be done to remove zebra mussels once they have become established in a body of water, according to the NPS. Ecologists have been "battling" with the invasive species for 50 years, Tamburri said.

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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.

In this April 24, 2026, file photo, an oil tanker HELGA berthed at one of Iraq's southern offshore oil terminals near Basra as it prepares to load crude oil, becoming the second vessel to arrive since the closure of the Strait of Hormuz.<br>Mohammed Aty/Reuters, FILE

Currently, the Strait of Hormuz is experiencing severe disruptions. Last week, the the U.S. resumed its naval blockade on the strait after Iran fired upon oil tankers in it.<br>More than 1,500 ships remain idle in the  Persian Gulf and hundreds more are anchored in the Gulf of Oman, according to the paper.

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