Using a bottle of water to track Yangtze finless porpoise

How do we count the number of species in a lake? How do we know how many Yangtze finless porpoises are in the water? Environmental DNA technology makes it an easy task.

At the Yueyang Tower water observation point near East Dongting Lake in central China's Hunan Province, Li Benchao, director of the Dongting Lake Ecological Environment Monitoring Center of Hunan Province, and his team are carrying out a special survey. 

Their mission is to collect water samples and use environmental DNA technology to analyze the current status of aquatic biological resources in the Yueyang section of the Yangtze River and Dongting Lake.

"In the past, the detection of aquatic species such as the Yangtze finless porpoises and fish mainly relied on manual observation. This method was not only time-consuming and labor-intensive, but the data obtained was also inaccurate. Environmental DNA (eDNA) technology, as an emerging biological monitoring method, can achieve effective monitoring even when the density of the Yangtze finless porpoise is low," said Li.

A creature leaves traces as it moves through its surroundings. The genetic material in the matter is known as environmental DNA. Researchers can detect whether there are Yangtze finless porpoises in the water only by analyzing a bottle of water collected from the lake.

"Through eDNA biological monitoring, we have found the Yangtze finless porpoises in multiple sections of Dongting Lake. In the past, they were mainly concentrated in the Sanjiangkou area of the Yangtze River. Now, they also appeared in the Xiangjiang River Basin, and their population has reached over 160, which is a significant increase. The number of benthic animal species is also increasing year by year, and currently there are more than 50 species," added Li.

As the environment of Dongting Lake improved, the number of the Yangtze finless porpoise has increased from 110 in 2017 to 162 in 2022. Li's research team plans to add more monitoring spots to better track and protect the Yangtze finless porpoise.

(Cover image via CFP)