“Reef balls”: New ways to stop beach erosion tested on Desroches Island

The balls are constructed on the islands making them easier to transport. (Islands Development Company)

(Seychelles News Agency) – The Islands Development Company (IDC) is testing a new type of artificial protection called ‘reef balls’ against beach erosion on the island of Desroches in Seychelles, said a top IDC official.

The islands of Desroches, Remire and Platte are currently facing the dangers of beach erosion, which could eventually bring the islands’ existence in peril especially as they are coralline and low-lying islands. Various methods to tackle erosion have been used in the past with little to no effect.

“Seeing as nothing was being effective, we decided to look elsewhere and find out what can be done and we found a company in the Maldives, that had adopted a technique called reef balls, that has had great results,” Glenny Savy, the IDC chief executive, told reporters on Monday.

The same company has helped IDC with the installation of reef balls along the beach on Desroches Island. At the moment, 80 of the projected 800 reef balls have been put in place at about 150 metres from the beach. The balls are constructed on the islands, making them easier to transport. Each one cost around $116 to make.

A reef ball is a designed artificial reef module that mimics the structure and function of a natural reef made with special concrete additives with a pH. (Islands Development Company)

A reef ball is a designed artificial reef module that mimics the structure and function of a natural reef made with special concrete additives with a pH similar to seawater. This assures compatibility with marine environments and enhances its attractiveness to colonising organisms.

“The balls have to be placed in an exact pattern and that is why the company made a comprehensive study of the coastline before the laying works began, as they needed to find the perfect placement and number of balls to install to ensure maximum effectiveness,” added Savy.

Covering 394 hectares, Desroches is the largest island in the Amirantes group and the closest to the granitic islands, lying 230 kilometres southwest of Victoria, the capital of Seychelles, an archipelago in the western Indian Ocean. The island is home to a resort of the Four Seasons chain.

The balls not only protect the coastline but also reduce the strength of the current and waves crashing on the beach and, therefore, reduce erosion. The project to install 800 reef balls on Desroches is expected to be completed by December. Then works will move to Platte and Remire islands between January and February of 2023.

The balls not only protect the coastline but also reduce the strength of the current and waves crashing on the beach and, therefore, reduce erosion. (Islands Development Company)

The project is being closely monitored by the Department of Environment, as it is also looking at projects to curb beach erosion, which is quite common on Mahe, the main island, and other inner islands.

“We wanted to see how the reef balls work on the outer islands, as we are hoping to be able to place them in areas around Mahe, where the beaches are severely affected by strong waves and currents,” said Annie Simeon, the principal climate adaptation officer at the Department of Environment.

Should the reef balls be successful, it will not only protect Seychelles’ biggest selling point to visitors but also create an ecosystem for fish and other sea creatures to thrive, in line with Seychelles’ aim of environmental protection.