A tenacious, non-native seagrass species, spreading across oceans for over a century, has been discovered in U.S. waters for the first time.

Halophila stipulacea, a small-body seagrass native to the Indian Ocean, began spreading in the 1800s following the opening of the Suez Canal in Egypt, a man-made waterway that connects the Red Sea to the Mediterranean Sea and serves as a key trade route between Europe and Asia, Justin Campbell, a professor at Florida International University specializing in marine ecosystems, told
.

A second massive influx of Halophila stipulacea, originating in the Mediterranean Sea and traveling across the Atlantic, has begun to colonize parts of the Caribbean and has now been discovered in Miami's Biscayne Bay, Campbell stated.

Scientists believe the spread of Halophila stipulacea is primarily attributed to ship traffic.

"It's easy to see how vessels could accidentally pick up fragments of this seagrass and transport them over long distances," Campbell explained. "When this species is first identified in a new location, it's often found in marinas or boat anchoring areas."

The theory proved accurate in South Florida. The species was first observed by a diver or snorkeler near the Crandon Marina in early August, according to researchers. Once Campbell was notified of its presence, tests confirmed the presence of Halophila stipulacea in Biscayne Bay.

The invasive seagrass patch within the marina has expanded to the size of a basketball court, and several patches have spread beyond the marina as well, Campbell stated. Since the area is popular for boating, scientists are concerned about the potential for further dissemination, Campbell said.

Based on the size of the patch, researchers believe the invasive seagrass has been present in the marina for several years, Campbell said, adding that it "easily" resembles some of the native vegetation, making it difficult to detect. A variety of invertebrates have established themselves within the invasive seagrass.

Furthermore, the species is a "clonal plant," meaning it produces asexual copies of itself, enabling rapid propagation, Campbell said.

"Certain species have the ability to break apart and then drift a certain distance," he explained. "And then these fragments can re-establish themselves and start a new population."

In 2021, the species was determined to be a high risk for arrival, establishment and potential impacts in Florida, researchers found . In addition, invasive species tend to do well when there are disturbances, and the warming of temperatures in ocean waters could be assisting in the spread, Deah Lieurance, an assistant professor of invasive species and biology management, told
.

With its arrival, scientists are concerned about the fate of Florida's 16,000 acres of native seagrasses, particularly in light of experiences in other regions, Campbell emphasized. In places such as the Caribbean and the Western Atlantic, Halophila stipulacea has effectively dominated and displaced the indigenous aquatic plants, he noted.

"It's anticipated to outmaneuver Florida's native seagrasses and … around the island of Dominica," Lieurance stated.

Invasive species have proven to be costly in the U.S.

Between 1960 and 2020, reported costs associated with biological invasions in the U.S. reached at least $1.22 trillion, as reported in a research article published in the journal Science of The Total Environment .

The study discovered that annual invasion costs have dramatically increased, soaring from $2 billion between 1960 and 1969 to $21 billion from 2010 to 2020.

Invasive species have the capacity to reshape entire ecosystems and eliminate native species, Lieurance explained.

"These would be irreversible consequences, such as species extinctions, or altering the soil or another aspect of the ecosystem in a way that can't be repaired -- you can't go back and restore it," Lieurance said.

Scientists are currently investigating whether it would be a productive and cost-effective way to eliminate as much of the Halophila stipulacea as possible, Campbell said.

"I believe there will definitely be broader conversations about how effectively we can control this -- whether we should actively manage it," he said.

One idea would be to inform boats arriving from the Caribbean to be mindful of anything they're carrying on their vessel, which would be a groundbreaking mitigation effort, Campbell said.

In addition, specialists in invasive species are closely watching to see if more [of the invasive species] can be caught, Lieurance said.

The Florida Fish and Wildlife Conservation Commission did not immediately respond to
' request for comment.