丰度测定 measurement of 15N abundance
Practice 1
A symbol of abundance to the rest of the world, the Amazon is experiencing a crisis of overfishing. As stocks of the most popular species diminish to worrisome levels, tensions are growing between subsistence fishermen and their commercial rivals, who are eager to enrich their bottom line and satisfy the growing appetite for fish of city-dwellers in Brazil and abroad.
In response, peasants up and down the Amazon, here in Brazil and in neighboring countries like Peru, are forming cooperatives to control fish catches and restock their rivers and lakes. But that effort, increasingly successful, has only encouraged the commercial fishing operations, as well as some of the peasants' less disciplined neighbors, to step up their depredations.
“The industrial fishing boats, the big 20- to 30-ton vessels, they have a different mentality than us artisanal fishermen, who have learned to take the protection of the environment into account,” said the president of the local fishermen's union. “They want to sweep everything up with their dragnets and then move on, benefiting from our work and sacrifice and leaving us with nothing.”