Seagrass plays an important role in preserving beaches

Biologists and engineers from The Netherlands and Mexico are describing studies and field observations around the Caribbean Sea that demonstrate just how effective seagrass beds are in protecting tropical beaches from erosion. The experts report that seagrass beds can reduce the need for the expensive beach nourishments that are currently used.

Study lead author Rebecca James is a PhD-candidate at the University of Groningen and the Royal Dutch Institute for Sea Research (NIOZ).

“A foreshore with both healthy seagrass beds as well as calcifying algae, is a resilient and sustainable option in coastal defense,” said James. “Because of erosion, the economic value of Caribbean beaches literally drains into the sea.”

The study authors focused on beaches of the Caribbean Sea, where economies largely  depend on revenue from tourism that is centered around the beaches.

“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 study co-author Rodolfo Silva.

“Until now, expensive coastal engineering efforts, such as repeated beach nourishments and concrete walls to protect the coast, have been made to combat erosion. Rising sea-level and increasing storms will only increase the loss of these important beaches.”

The team conducted a simple experiment to determine to what extent seagrass beds are able to hold sand and sediment on the beach foreshores.

“We showed that seagrass beds were extremely effective at holding sediment in place,” said James. “Especially in combination with calcifying algae that ‘create their own sand,’ a foreshore with healthy seagrass appeared a sustainable way of combating erosion.”

Study co-author Dr. Brigitta van Tussenbroek said the team discovered that the amount of erosion was strongly linked to the amount of vegetation. At beaches where seagrass beds were destroyed, there was an abrupt increase in erosion, which created a need for expensive modifications.

Bas Roels of World Wildlife Fund Netherlands said: “To date, seagrass beds are too often regarded as a nuisance, rather than a valuable asset for preserving touristically valuable coastlines. This study could change this perspective completely.”

The research is published in the journal BioScience.

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By Chrissy Sexton, Earth.com Staff Writer