英语听力：自然百科大堡礁：珊瑚礁到雨林

But there are now less than 2,000 living here, and they are becoming rarer all the time.-Before European settlers arrived, much of the coast here was covered in forest. And a lot of that was jungle just like this. This is a vibrant ecosystem in its own right. It's full of reptiles, of birds, and you can hear all around me. But today, things have changed significantly. Much of the coastline that busts the Great Barrier Reef, 80 percent of it, in fact, has been cleaned for agriculture, and much of that has been totally cleaned for sugarcane. Obviously, this has a dramatic impact on the terracing environment, but it also has a significant effect on the reef itself.

And it's not only crops, cattle ranches, fish farms, six large coastal cities and many holiday resorts along the coast all have an impact on the reef system. Without the natural vegetation controlling the movement of water in the seidments it carries, heavy rain now washes millions of tons of silt, often laced with damaging fertilizers of pesticides straight into the lagoon. Sediment pollutants can be so extensive, they sometimes spread all the way to the outer reef. In the seagrass meadows, the fine silt thrashes the life-dependent plants and fertilizers feed o* that choke the life from them. When the meadows die, the turtles, dugongs and baby fish that depend on them die too. Near the shore, the water can be so murky that less light reaches the corals, so most fringing reefs have also disappeared.

英语听力：自然百科 大堡礁：珊瑚礁到雨林—29（在线收听）

英语听力：自然百科大堡礁：珊瑚礁到雨林—29（在线收听）