This is Scientific American — 60-Second Science. I'm Christopher Intagliata.
Today we have sophisticated buoys packed with instruments, and robotic underwater drones. But a more than a century ago the seas were surveyed by different types of autonomous data-gathering instruments. Which also happened to be alive:
"We just call them sea otters and white sharks and bluefin tuna." Kyle Van Houtan is director of science at the Monterey Bay Aquarium. And what he means is that marine mammals and fish and seabirds concentrate unique chemical clues about the ocean and what lives in it, within their tissues. "In their bones, in their feathers, in their vertebrae, in their earwax."
For his most recent study, Van Houtan needed to locate feathers from some long-dead birds.
"Let's see, so I'm just looking here, that was a Bulwer's petrel, from French Frigate Shoals—I have the database open in front of me here..." Molly Hagemann, who describes herself as 'a librarian for dead animals' at Honolulu's Bishop Museum, was able to help.
"So that one was collected in May 1891. And then we also had a brown noddy from 1895..."
The scientists analyzed the ratios of heavy to light nitrogen isotopes in those old feathers, compared to ratios in modern-day specimens. And they found that Pacific seabirds of yore ate diets dominated by fish. But the birds of today were fishing farther down in the food web. And seemed to be eating nearly twice as much squid as their ancestors did—maybe due to the combined effects of commercial fishing and climate change. The details are in the journal Science Advances.
Now, nothing against consuming calamari. But: "KVH: It's a risky business to depend on squid. Because squid go through these boom/bust cycles." So the shift in protein source could one day leave the birds hungry.
But the bigger picture is that it appears food webs in the central Pacific have lost components and become less complex over the last 130 years—meaning they're less resilient to changes.
KVH: "It's more than just climate: It's all the noise we're adding to the ocean. All of the contaminants, that were plenty in the ocean, the microplastic. It's a warming ocean. It's an ocean with more nutrients. It's an ocean with less oxygen.."
And it's an ocean with less capacity to recover from all those insults.
Thanks for listening for Scientific American — 60-Second Science. I'm Christopher Intagliata.
现在，我们拥有装满仪器的精密浮标，还有水下自动无人机 。但在一个多世纪以前，海洋调查是通过各种自主数据收集仪器完成的 。这些仪器如今依然存在：
“我们称之为海獭、白鲨和蓝鳍金枪鱼 。” 凯尔·范·休坦是蒙特利湾水族馆的科学主任 。他的意思是海洋哺乳动物、鱼类和海鸟集中于身体组织内的独特化学线索，这些线索与海洋及海洋生物有关 。“线索存在于它们的骨骼、羽毛、脊椎和耳垢中 。”
“那只鸟的收藏时间是1981年5月 。后来我们还在1895年收藏了一只白顶玄鸥 。”
科学家分析了那些旧羽毛中氮同位素从高到低的比率，并将其与现代标本的比率进行了对比 。他们发现，过去太平洋海鸟的食物主要以鱼为主 。但现在的鸟儿则在食物链更低端 。看起来它们所摄取的鱿鱼数量是其祖先的近两倍，这可能是因为商业捕鱼和气候变化所带来的联合影响 。该研究的详细内容刊登在《科学进展》期刊上 。
鸟类食用鱿鱼没有什么问题 。但是：“凯尔·范·休：鸟类依赖鱿鱼是有风险的 。因为鱿鱼数量时多时少 。”因此，蛋白质来源的转变有一天可能会让鸟类挨饿 。
凯尔·范·休：“这不仅仅是气候原因：这是我们加给海洋的所有噪音 。海洋里还有很多微塑料污染物 。海洋温度不断升高，养分越来越多，但是氧气越来越少 。”
谢谢大家收听科学美国人——60秒科学 。我是克里斯托弗·因塔利亚塔 。
1. in front of 在…面前；
He tipped the table over in front of him.
2. due to 由于；因为；
And that will likely worsen as analysts predict a decrease in the labor force in the next year or two due to a rise in the aging population.
3. depend on 依靠；依赖；
Needy and handicapped people depend on government relief for their support.
4. go through 经历，经受（尤指苦难或艰难时期）；
As you go through life, you'll experience joy, pain, loss, discovery, and a thousand other different thoughts and emotions.