From VOA Learning English, this is the Environment and Science Report.
Many science fiction stories tell about explorers arriving in a new world. The explorers then use some kind of high-tech device to test for breathable air or signs of life. But here on Earth, science fiction is becoming reality through a new sampling technology called environmental DNA, or eDNA for short. Scientists can use it to identify rare or invasive species, study biodiversity or estimate fish populations with just a little air or water.
Ryan Kelly is an ecologist at the School of Marine and Environmental Affairs at the University of Washington in Seattle. He works in a laboratory there with other researchers. They study the genetic material released by living creatures.
"Essentially we can take a sample of soil or air -- and in our case -- water, and we can sequence the DNA out of it and tell you what is there."
Ryan Kelly says he and his research team are studying water samples collected from Puget Sound. He says the cost of gene sequencing has "plummeted in recent years." That makes DNA testing more widely available.
Environmental DNA can be used in two ways. One is to identify the creatures that live in a certain place. The other is to confirm the presence or lack of a specific creature.
Caren Goldberg heads the new eDNA lab at Washington State University in Pullman, Washington. She is one of the first biologists in the northwestern United States to take the technology from the testing phase to actually using it.
"It is extremely useful for species that are really hard to find. I have spent many hours looking for species that I was pretty sure were there -- looking under rocks, looking in water, doing all kinds of surveys."
Caren Goldberg sees eDNA as a way to get answers more efficiently, safely and with less destruction compared to traditional survey techniques. Until recently, scientists depended on snorkeling, netting or using an electric current to temporarily capture fish.
"We're absolutely at this point where proof-of-concept has been established. I don't think everyone necessarily is on board yet, but I think the majority of the people are on board."
This newer way to identify what lives in the environment is becoming popular around the world. Animal experts in Vietnam are using the eDNA to find the last, wild Yangtze giant softshell turtles. One researcher on the Caribbean island of Trinidad is using the sampling technology to find endangered golden treefrogs. And in Madagascar, it is being used to identify amphibian diseases.
Ms. Goldberg has used eDNA testing to confirm the local extinction, disappearance, of a leopard frog in the American state of Idaho. She has also been asked to document the spread of the New Zealand mudsnail in the state of Washington. The creature has been found in lakes and other waterways across the state.
Now, the U.S. Bureau of Land Management wants Caren Goldberg to look for the Columbia spotted frog in two other western states. The rare amphibian is a candidate for the federal government's threatened species list.
Scientists working with the technology say they do not expect robots to replace field biologists anytime soon. But the old-fashioned field work could soon be more targeted.
A related research goal is to show how long environmental DNA can last and how far it can travel in different environments.
And that’s the Environment and Science Report from VOA Learning English. For more environment, science and agriculture reports, go to our website learningenglish.voanews.com. I’m Jonathan Evans.
1.sequence n. [数][计] 序列；顺序；续发事件 vt. 按顺序排好
The chronological sequence gives the book an element of structure.
2.amphibian n. [脊椎] 两栖动物；水陆两用飞机；具有双重性格的人 adj. 两栖类的；[车辆] 水陆两用的；具有双重性格的
Both the toad and frog are amphibian.
3.snorkeling n. 浮潜；潜水；浅滩潜水 v. 用水下通气管潜航；用通气管潜泳（snorkel的ing形式） adj. 潜浮的
Swim off the side of the ship and snorkel in some of the clearest waters imaginable.
4.leopard n. 豹；美洲豹
The young leopard separated from its mother would be eaten by other beast.
1.I don't think everyone necessarily is on board yet, but I think the majority of the people are on board.
on board 支持的; 赞同的；在船（火车、飞机）上
We were able to keep some moderate and conservative Democrats on board.
The six astronauts on board will spend ten days in space.
很多科幻小说都讲述探索者来到新世界，然后使用新型高科技设备来测试可呼吸气体或生命迹象。但在地球上，通过名为环境DNA(或eDNA)的新样本技术，科幻小说正在成为现实 。科学家们能使用这种技术来识别罕见或侵入性物种，只需少量空气或水来研究生物多样性或估计鱼群大小 。
这种寻找环境中生物的新方法在全世界都开始流行，越南动物专家使用eDNA来寻找最后的野生斑鳖。加勒比岛国特立尼达的一位研究者使用这种样本技术来寻找濒危金色树蛙 。在马达加斯加，该技术被用来识别两栖动物疾病 。