VOA常速英语2018--鼠类过多不利于岛屿生态健康（在线收听）

According to the study, rats have decimated seabird populations across 90 percent of the world’s island archipelagos. Professor Nick Graham of Lancaster University in Britain says at a recent visit at the Chagos archipelago in the Indian Ocean, there were stark differences between the islands populated with rats compared to the ones that were rude and free.

根据该研究，老鼠的存在导致全球90%群岛上的鸟类数量减少。尼克·格雷厄姆教授来自英国兰开斯特大学，他在最近到访印度洋的查戈斯群岛时表示，有大量老鼠的岛屿和一片蛮荒的岛屿是迥然不同的。

Where there’s rats, the sky’s empty, the island’s very quiet. You go to an island with no rats, the sky’s full of sea birds, it’s very noisy and it smells. It’s very pungent. You can smell the guano or the bird poo in the air. The scientists found guano which is sometimes used as fertilizer to be crucial to the functioning of tropical ecosystems.

有老鼠的地方，天空空荡荡的，岛上也悄无声息。而没有老鼠的岛上，天空中都是海鸟，四处喧嚣，而且味道非常刺鼻。空气中都弥漫着鸟粪的味道。而此前，科学家发现，鸟粪有时候可以用作肥料，对于热带生态系统的运作至关重要。

The seabirds, they’re flying great distances away from the islands, and they’re feeding in what we call the pelagic ecosystem, so the deep areas of the ocean. And then there they’re flying back to the islands to roost and to breed, and that’s when they’re depositing these rich nutrients that they’ve captured in the open ocean back onto the islands.

Now when those nutrients go onto the coral reef which was showing that it’s boosting the productivity and the functioning of those reefs, rats eat bird eggs, chicks and even adult birds. Rat-free Islands saw significantly more sea bird life and had nitrogen in the soil which made its way into the sea benefiting filter-feeding sponges, turf algae and fish.

这些营养物质会进入珊瑚礁中，这表明鸟类可以提高珊瑚礁的生产力和功能，但鼠类会吃掉鸟蛋、雏鸟、甚至成年鸟类。没有老鼠的岛屿上，鸟类数量会有大幅增长，土壤中也有很多氮元素，而当氮元素进入大海中之后，又有助于滤食性海绵动物、草皮藻类和鱼类的生长。

Fish, unique in coral reefs and that they provide important processes or functions that help reefs be healthy and to bounce back from disturbances. These are things like clearing away algae following disturbances, so new corals can settle and grow back on the reef. The number of fish was also 50 percent greater in the waters of rat-free islands.

鱼类对于珊瑚礁而言有独特的作用，它们可以进行重要的流程，承担着重要的功能，可以帮助珊瑚保持健康的状态，即便受到外界干扰也能迅速恢复。这些作用就像是帮助海藻从干扰中恢复，这样，新的珊瑚就可以在珊瑚礁上落脚并生长。与有老鼠的岛屿相比，鱼类数量多了50%。