英语听力：自然百科 美国-史密斯岛（在线收听）

 Smith Island is a lonely outpost, 12 miles out in the lower Chesapeake Bay. The shallow glassy waters around the cluster of islands that comprise Smith Island are some of the best blue crab habitat in the bay. For more than 300 years the people here have endured nature's hardships. But increasingly, they sense that a more precarious future lies ahead. The watermen are bringing in smaller catches and profits falling down. The population has dropped from more than 800 to about 300 over the last 100 years and Smith Island is losing its land. Most of the island is only one foot above sea level. The higher areas where the people live are just 2 to 4 feet above the water. Coastal ecologists say the Chesapeake Bay has risen by more than a half foot over the past century and continues to swallow the land. Crumbling wooden crab shacks and battered bulwarks are testimony to the island's vulnerability to the sea. To help the islanders beat back to bay, the Army Corps of Engineers launched a plan to install new bulkheads and stone breakwaters around Tylerton, part of a multimillion-dollar plan to slow erosion and persuade people to stay. Despite this project, Smith Island may be running out of time.