It’s a barrier dividing us’: How a concrete seawall split this Japanese island village

Rising before dawn on an early summer day in July 2022, Hisami Take took a walk along Katoku beach in Amami Ōshima, an island nestled in the far south of Japan. Looking along the beach, she saw an animal track on the sand stretching from the ocean, then U-turning back into the water.

The track, she says, likely belonged to an endangered loggerhead sea turtle that is known to come ashore to lay eggs. “This year, no eggs were found. Maybe the shiny orange construction rope is signalling the turtles to turn away.”

Take, a 49-year-old Amami resident, and many other locals on the island fear that an enormous concrete seawall about to be constructed on the beach in place of the rope could make such tracks more common by blocking endangered species like the turtle from coming to the beach. The construction firm and local state government, Kagoshima Prefecture, did not respond to the BBC’s request for comment.

Opinion on the years-long development has split the local community. Scientists and many locals worry the seawall could immovably obstruct the already threatened wildlife of the biodiverse island and argue that natural solutions such as planting local species would provide better protection from coastal erosion. Advocates of the seawall, meanwhile, say it’s necessary to give both people and local land vital protection from coastal erosion and typhoons, with some seeing it as welcome infrastructure development.

It’s a debate that goes to the heart of how coastal communities will respond to rising seas and more intense storms due to climate change. Hard coastal protection measures like concrete seawalls have been implemented in some areas of the world for decades, but many scientists now favour natural defences, which aim to improve local ecosystems to bolster resilience. When the two are in competition, which wins out?

With its white beaches and beautiful coral reefs, Amami Ōshima is widely known for its candid natural beauty. While it makes up only 0.5% of Japan’s land, much of it is a biodiversity hotspot: it is home to 95 globally endangered species, 75 of them endemic, and over 1,800 species of plants. In July 2021, a part of Amami Oshima, together with sites on three neighbouring islands, was registered as a Unesco World Heritage Site for its outstanding ecological significance.

Amami retains many of its rich forests and mangroves, but Katoku is its last coastal village without concrete defences and with a free-flowing river. The area is home to endangered species such as the leatherback turtle, which has lived since before the dinosaur extinction, and the Amami rabbit, an ancient species sometimes referred to as a “living fossil”.

“I could not believe a place like this existed in Amami – so mystical and almost divine,” says Take, recalling her first visit to Katoku when she was 19. “Growing up in Amami, I never had a ‘real’ beach around. All the other beaches and rivers [on Amami Ōshima island] were hardened with concrete, but Katoku still has a beach, a river delta where freshwater flows freely from the Katoku mountains and a dynamic sand dune.”

Now, though, an enormous seawall is being constructed at the beach by Kagoshima Prefecture. It says it is building the wall, which will be 180m (590ft) long and 6.5m (21ft) high, “for the safety and security of lives and assets of residents from coastal erosion caused by natural disasters such as typhoons”.

The decision to build the seawall was taken in response to concerns raised by local residents back in 2014. They submitted a request to the local Setouchi town council that governs Katoku village to take measures to prevent what they believed to be dune erosion caused by two typhoons that year. They were concerned such erosion could endanger an ancestral resting place, central to their religious tradition, which lies some 70m (230ft) above the waterline. However, they did not specifically request a seawall as the solution.