Just over a year ago we started seeing this grass floating all around the island especially in protected bays and harbours. I even saw it far offshore in the Atlantic while freediving. It was quite a surprise to see it suspended in the water column thirty miles offshore.
From http://www.sciencedirect.com/science/article/pii/S0304377013001289 "Native to the Red Sea and western Indian Ocean, H. stipulacea spread to the Mediterranean Sea in the late 1800s and became established in the eastern Caribbean in 2002. The species has dispersed north and south of its first sighting in Grenada and now spans a latitudinal distance of 6° (>700 km), most likely facilitated by a combination of commercial and recreational boat traffic."
Well, this grass notoriously spreads very quickly often displacing other native seagrass beds. Our country's seagrass beds are incredibly important providing food and habitat for a huge variety of marine animals. In fact, there are some islands without much seagrass bed type habitats that wouldn't see certain creatures at all if it were not for large seagrass beds from islands like Antigua and Barbuda. Some species of sea turtles would be severely effected if our native seagrass habitats were overrun.
Last year my company, Adventure Antigua took part in an in-water sea turtle study with our Antigua Sea Turtle Project. We surveyed the Carlisle Bay area for several days and never noticed any beds of halophila stipulacea, but yesterday Roddy Grimes-Graeme and I saw large beds in quite a few areas there. The photos attached show one spot where it seemed to be mixed with and displacing turtle grass.
I have no idea how we can deal with this but just shows another reason why we have to be careful to protect marine habitats and their species. Habitats and related species that are already under threat or pressure from human activity are easily damaged by invasives. I'm sure we'll hear more and more about this situation over the next few years. We here in Antigua and Barbuda need to understand that it's not just reefs and mangrove habitats that need protection. Seagrass beds are incredible hot spots for biodiversity (read more) and equally important in the fight against climate change (read more).