Nigeria, Nov. 26 -- The fishermen in Ikuru - a small Andoni community on the coast of Rivers State, Nigeria - have a lot to lament.

For generations, the settlement on the edge of the Atlantic lived by the tides. At dawn, men paddled out in narrow canoes while women waited ashore to buy the day's catch. The sea provided enough to feed families and sustain the village.

It still does, but far less reliably, especially in some seasons.

On a recent, soggy afternoon, a dozen men and a woman sat on traditional benches under the sparse shade of trees and shrubs rising from the white coastal sand, their eyes on the restless sea. None had gone out to fish for days. The air hung heavy with moisture; the ocean waves crashed, retreated and gathered...