UVI SEEKS HELP STOPPING INVASIVE SEA GRASS

December 9, 2014
Halophila stipulacea is an invasive species of sea grass that is quickly spreading and wrecking havoc throughout the territory’s waters, and University of the Virgin Islands faculty and student researchers are trying to find ways to stop its expansion.

According to a press release issued by the University, Halophila stipulacea originates from the western Indian Ocean and is believed to have spread into the Mediterranean and Caribbean seas in ship ballasts and by fragmentation caused by anchoring and other bottom disturbances.

“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.”

Halophila stipulacea sea grass.

Invasive Halophila stipulacea sea grass.

To that end, Forbes said faculty and student researchers have been vigorously working to combat the sea grass “with the fill force of research, knowledge and education.”

Sam Mitchell and Jess Keller, students in UVI’s Marine and Environmental graduate program, recently completed studying the invasive grasses as part of the capstone project for their Masters in Marine and Environmental Science degrees. Their research showed that local animals eat the problematic sea grass, but not quickly enought to prevent its spread.

Sea grasses that are most often seen in local waters include the Syringodium filiforme, Thalassia testudinum, and Halodule wrightii. The invading sea grasses threaten their existence by competing for resources and space. The fast growth rate and ability to sprout from a tiny fragment enable the foreign sea grass species to rapidly establish new colonies in bare sand, Mitchell explained.

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

Another concern Mitchell pointed out is that the invasive species has been seen growing in the sand halo that typically surrounds coral reefs–an area where sea grasses are generally absent and that provide an ideal location for the invasive species of sea grass to flourish.

In addition, Keller said it is important to identify bays and the sheltered waters of estuaries that have not yet been invaded by the foreign sea grass.

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

Vessel operators are asked to avoid anchoring in sea grasses to help limit damage to native species and that would encourage the growth of non-native ones.

UVI is asking the public to report any sightings of Halophila stipulacea in local waters to its Center of Marine and Environmental Science at (340) 693-1380. This is especially important if the species appears in any of the native sea grass habitats. Halophila stipulacea is found in disturbed areas of between 98-147 feet in depth, and its leaves are usually between .11 to .59 inches long and .11 to .38 inches wide.

See link for pictures of the sea grass:
http://viconsortium.com/featured/uvi-researchers-seek-publics-help-to-stop-invasive-sea-grass-in-vi-waters/