A Caribbean beach after a hurricane. Seagrass is a great natural protector of beaches against storms and reduces the need for human intervention. Rebecca James / Royal Netherlands Institute for Sea Research

Caribbean Islands Face Loss of Protection and Biodiversity as Seagrass Loses Terrain

Tropical islands have an important ally when it comes to battling storms and sea-level rise: seagrass.

During Hurricane Irma, an extremely powerful Category 5 storm that hit the North Caribbean in 2017, NIOZ scientist Rebecca James witnessed how native seagrass meadows along the coast of Sint Maarten held their ground, reduced coastal erosion and lowered the chances of flooding. In the years of research during her Ph.D., she saw the pressures on this natural storm protection increasing. In her dissertation, The future of seagrass ecosystem services in a changing world, James warns that further loss of these green meadows will leave tropical islands vulnerable and will exacerbate the negative effects of climate change.

The flexible grass, that grows in shallow bays and lagoons throughout the Caribbean, is a natural wave dampener. As it sways back and forth, it removes energy from the waves, keeps the sand on the seafloor stable and, thereby, protects the beach against erosion. James says, "It is a great natural protector of beaches and reduces the need for human intervention, such as sand nourishments and seawalls."

Guardian of biodiversity

Seagrass offers more than protection to the islands and its people. The underwater meadows form a rich environment in which marine life, from micro-organisms to large animals, thrive. In turn, this benefits the local fishing communities. James: "In science, we call these ecosystem services." And seagrass serves many. James notes, "Through photosynthesis, seagrass removes CO2 from the water, it provides food and shelter for fish, turtles and sea urchins." Loss of these meadows not only puts tropical beaches at risk from erosion, it threatens all the species that rely upon them.

Scars that take years to recover

The biggest threats come from human disturbance, invasive species and bad water quality on the coasts. James says, "Tourists flock to the Caribbean for the beautiful beaches and clear waters. Resorts, restaurants and bars have been built throughout the Caribbean to support tourism, however, often at the expense of the natural environment." Dunes had to make way for hotels, seagrass -and seaweed were removed to create perfectly groomed beaches, feet trample the meadows, and boat anchors leave scars; physical damage that takes years to recover.

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