BEIJING – A sea wall being built in China will keep waves out but allow a local species of crab to migrate across the tidal barrier to get to its habitat.
It will do this through a specially designed corridor, measuring 1m wide and 80cm deep, which features a gradually ascending walled passage to allow the crustaceans to climb up and over the sea wall which is being built in Haining city located in Zhejiang province.
These biological migration corridors, a first for the country, were designed by the Zhejiang Institute of Hydraulics and Estuary, which it deemed as necessary to protect local wildlife and preserve balance in the ecosystem.
More such corridors will be constructed over the next year or two for hedgehogs, rabbits and other animals that need to move between habitats on both sides of the wall, mostly in Zhejiang and Jiangsu provinces, said Mr Xu Chao, who is leading the 14.4km sea wall construction project in the Jianshan section in Haining.
“When we planned this project, we took into account the need to establish a corridor to provide a migration route for the animals,” he said.
Construction of the corridor began in March and was designed to mimic conditions suitable for the crabs.
Starting from a reed pond by the Qiantang River, the corridor will zigzag upwards using pebbles to create stepping stones for the crabs.
The path is lined with bricks, with soil and vegetation scattered along the entire length of the corridor. Crumbs of rotting meat are also sprinkled along the path to feed the crabs.
The riverside in the Jianshan section is a silted, convex bank with abundant beach resources and natural plant communities, including woody bulrushes and reeds, which provide a suitable habitat for crabs. It is one of the four key distribution areas for wintering waterfowl in the wetlands of Hangzhou Bay and the Qiantang River estuary.
In the past, because of the unique structure of the sea wall – with its vertical face, or wave barrier, exceeding 3m in height, and with no crossing corridors – ecological migration was impossible.
Mr Xu said this would often result in the crabs dying due to exposure to the sun or from being crushed.
Now, he said, the crabs would have access to safe passage. CHINA DAILY/ASIA NEWS NETWORK
