Tidal Power.

[cratehorus]

Not sure if these situations are the same but...
http://www.pbs.org/wnet/nature/episodes/...coco/5808/

Accordingly, a stone causeway, about 12 miles long, was built across the shallow waters of Bahía de los Perros (Dogs Bay) Cuba.

Unfortunately, almost as soon as the causeway was completed, it was clear that its presence had created a number of serious environmental concerns. The mangroves began dying off, and habitat for the birds was being lost. The causeway was cutting off seawater and tidal flow that would normally have been coming in and nourishing the rest of the coastal area. Levels of salinity and water temperature were affected. Fish were dying.

This barrage will be alot worse:
http://www.guardian.co.uk/environment/20....wildlife1

The land that would be submerged hosts about 68,000 birds in winter, including huge flocks of dunlins and shelducks, together with Bewick's swans, curlews, pintails, wigeons and redshanks. Breeding birds feeding on the estuary in summer include curlews, shelducks and oystercatchers. At least 30,000 salmon and tens of thousands of shads, lampreys and sea trout use the estuary to reach spawning grounds in the Usk and Wye rivers. Eels swim back down these rivers to reach spawning grounds at sea and millions of elvers return in the spring