Seagrass beds are so effective at protecting tropical beaches from erosion that they can reduce the need for the expensive beach nourishments that are currently used regularly, says a new study of the Caribbean Sea.
Around the beaches of the Caribbean Sea, almost a quarter of the Gross Domestic Product is earned in tourism. Yet “because of erosion, the economic value of Caribbean beaches literally drains into the sea”, say the authors of the new paper published by the Royal Dutch Institute for Sea Research (NIOZ).
“With the increase of coastal development, the natural flow of water and sand is disrupted, natural ecosystems are damaged, and many tropical beaches have already disappeared into the sea,” explained co-author Rodolfo Silva in a statement.
Until now, erosion has been combatted using expensive coastal engineering efforts, such as repeated beach nourishments and concrete walls to protect the coast.
However, the new research has unveiled a different approach. Based on studies around the Caribbean Sea, the scientists found that a foreshore with healthy seagrass beds and calcifying algae can provide effective coastal defence.
Using a portable and adjustable field flume to regulate water motion in a Caribbean bay, they observed when particles on the sea bed started moving.
“We showed that seagrass beds were extremely effective at holding sediment in place,” said lead author Rebecca James. “Especially in combination with calcifying algae that ‘create their own sand,’ a foreshore with healthy seagrass appeared a sustainable way of combating erosion.”
Along the coastline of the Mexican peninsula of Yucatan, the team put their theory to the test. At beaches where seagrass beds were destroyed, they saw a sudden strong increase in erosion, resulting in an immediate need of expensive beach nourishments.
The study opens opportunities for developing new tropical-beach protection schemes, in which ecology is integrated in engineering solutions, according to Mark van Koningsveld of Delft University of Technology.
Photo credit: Virginia State Parks/ CC BY 2.0