UVI Researchers Seek Help to Stop Invading Sea Grasses

In addition to lionfish, another invasive species is impacting the territory’s waters. A seagrass with the scientific name of Halophila stipulacea is spreading, and University of the Virgin Islands faculty and student researchers are asking residents to report the locations, UVI said in a Monday press release.

“Controlling the spread of this invasive species is critical due to its high capacity to replace and displace existing, native sea grass beds,” said Howard Forbes Jr., UVI Virgin Islands Marine and Advisory Service coordinator. “We are not sure what consumes this sea grass and so, should it completely dominate the marine ecosystem, it could mean the loss of food and habitat for some ecologically important marine organisms.”

The seagrass is not the sargassum weed that’s piling up on the territory’s beaches.

The invasive seagrass originated in the western Indian Ocean and is thought to have spread into the Mediterranean and Caribbean seas in ship ballasts and by fragmentation caused by anchoring and other bottom disturbances.

“It was first noticed in Guadeloupe and three years ago it was found here,” according to Rafe Boulon, who retired several years ago as chief of resource management for V.I. National Park.

According to the press release, UVI faculty and students are applying research, knowledge and education in an effort to combat the problem.

Marine and Environmental Sciences graduate students Sam Mitchell and Jess Keller recently wrapped up a study of the invasive sea grass as a part of the capstone project for their degrees. Their study revealed evidence that local animals eat the invasive sea grass, but the rate of consumption is not sufficient to prevent its expansion.

Native sea grasses are threatened by the invading sea grasses as they compete with the invasive species for resources and space. The fast growth rate of the invasive sea grass and its ability to regenerate from a tiny fragment enables it to rapidly establish new colonies in bare sand.

“This may have dire consequences for shallow, tropical marine ecosystems, since many organisms rely on native sea grasses for food and shelter,” Mitchell said.

Additionally sea grasses buffer currents, surge and beach erosion.

Mitchell said the invasive species can grow in the sand halo that typically surrounds coral reefs. This is important because this is an area where sea grasses are absent and represents an ideal location for the invasive species of sea grass to take root.

UVI asks that the public report any sightings of the invasive sea grass. Halophila stipulacea is commonly found in disturbed areas of between 98 to 147 feet in depth. Its leaves are usually between .11 to .59 inches long and .11 to .38 inches wide, which is small in comparison to the native species of sea grasses found within the Caribbean.

“An awareness campaign will target mitigation measures to prevent further expansion and any future invasions of nonnative species,” Keller said.

It is also important to identifying bays and estuaries that have not yet been invaded.

“These native strongholds are precious commodities at risk of invasion that need protection from the nonnative species,” Keller said. “Careful control of invasion vectors such as boat ballast storage areas, mobile attachments and the hulls of boats is necessary.”

Boaters are asked to avoid anchoring in sea grasses. This will limit damage to native sea grasses and encourage the growth of the nonnative sea grasses.

Anyone with knowledge of the presence of the foreign sea grass Halophila stipulacea, please report the sighting to the UVI Center of Marine and Environmental Science at (340) 693-1380.

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