Marine bacteria have evolved to resist the copper-based coatings used to prevent biofouling on ship hulls, according to researchers from the U.S. Naval Research Laboratory and Duke University. This evolutionary adaptation, highlighted in a study published October 13, 2026, forces a reevaluation of maritime anti-fouling strategies as bacteria thrive in previously toxic environments.
Genetic Adaptation in Marine Biofilms
Researchers investigating the persistence of marine organisms on ship hulls discovered that common bacterial species have developed significant copper resistance. The team conducted a study to analyze the genetic characteristics of various bacterial species, aiming to identify the genes responsible for their survival on copper-laden surfaces. By placing experimental panels in the water, the researchers allowed bacterial colonies to develop over a two-week period. Following this, they extracted DNA and sequenced the genomes of these colonies to test their tolerance against copper-based water treatments.
The study revealed that the bacteria could thrive at copper concentrations exceeding 70 milligrams per liter. This figure is notable when compared to the U.S. Environmental Protection Agency’s limit for short-term spikes in seawater, which is set at 18 micrograms per liter. The findings, published in the AVS journal Biointerphases, indicate that this resistance is widespread among the species studied, regardless of whether the colonies initially grew on copper-coated surfaces or control panels.
“We have observed increasing copper resistance in some of the ports our team frequents over the past decade, particularly in ports with heavy tourist [or] industry shipping activity,” said author Kenan Fears.
Bacterial Evolution Reduces Effectiveness of Copper Coatings
Author Kenan Fears noted that copper only became water-soluble following the oxygenation of Earth’s atmosphere, and its increased presence in marine environments has encouraged bacteria with superior defenses to continue reproducing.
This adaptation poses a growing challenge for the maritime industry. Biofouling, the unwanted accumulation of algae, barnacles, and other organisms, increases drag and fuel consumption on vessels while facilitating the spread of invasive species. As traditional copper-based coatings lose their effectiveness due to bacterial evolution, the maritime sector faces an urgent need for alternatives in the face of rising regulatory pressure.
Future Directions for Anti-Fouling Technology
The research team, which includes authors Kailey N. Richard, Sara M. Tuck, Sophie M. Colston, Maryssa A. Beasley, W. Judson Hervey, Kevin Le, Sean Brown, Katherine J. Franz, and Kenan P. Fears, aims to use these findings to target the molecular pathways that enable copper-resistant gene expression. By weakening the ability of bacteria to survive in copper-rich environments, they hope to improve antifouling efficacy.
“Our research suggests the smarter path moving forward is to design antifouling coatings that select microbial communities that either help deter macrofouler settlement — like barnacles or tubeworms — or do not impede the release of biocidal compounds,” Fears said.
AVS, founded in 1953, is an interdisciplinary society with approximately 4,500 members worldwide, including professionals across the fields of chemistry, physics, biology, and engineering. The article can be accessed at the DOI link 10.1116/6.0005640.