Scientists from the United States have presented a new method for tracking river health. To do this, they have created robotic labs that can collect samples several times a day for three weeks.
Researchers from the United States Geological Survey (USGS) have unveiled a new method for processing environmental samples and monitoring rivers. They used samplers, which are robotic laboratories – the devices collect and store water samples. Researchers call this fluid “environmental DNA” and it can help researchers detect imported and invasive animals, as well as microbes that can cause disease in humans and fish.
Environmental DNA (eDNA) is substances that are released by organisms into their environment in the form of pieces of skin, mucus, or waste products. In the case of aquatic organisms, this DNA can be found in the surrounding water within a few days.
To test the effectiveness of the method, samples were collected at different times and in different places. In 2017, Yellowstone National Park conducted a pilot sampling program at the confluence of the Kipping and Gardner Rivers. This was followed by more extensive sampling programs at three locations in the upper Yellowstone and Snake rivers.
The instruments used in this study can automatically collect samples every three hours for three weeks. Frequent sampling is key to detecting subtle changes in river health. For example, when a section of a river is just beginning to be colonized by a harmful invasive organism, a relatively small number of individuals are present in it, but the device can detect them.
A large number of samples provide biologists with more definitive information about whether harmful species are present in the river. As the authors explained, “a negative result gives some confidence that the target species has no DNA, while the lack of data due to rare samples does not give us any confidence.”