APR 20, 2017 5:56 AM PDT

Diatoms' DNA can be used as bioindicators for river health

As I learned during an ecology lab in college, biodiversity assessment is currently the most effective and accepted method of measuring the health of rivers and streams. As I also learned during that lab, the technique to assess biodiversity is quite tedious, requiring hours of laboring knee deep in a cold stream turning over rocks, scraping them clean of tiny macroinvertebrates, and later identifying each bitty critter one by one in the laboratory.

Checking stream health. Photo: Oceans Ltd.

But luckily for future college students, biologists from the University of Geneva (UNIGE), Switzerland, have recently published in Molecular Ecology Resources their successful attempts to establish a water quality index based on the DNA sequences of diatoms. Such DNA classification eliminates the need to identify each species visually, which may just change the way biomonitoring is conducted.

The biologists used diatoms as a case study because these single-celled algae are very sensitive to changes in water conditions, meaning they can act well as bioindicators of water quality and pollution levels. Previously, in order to utilize diatoms for biomonitoring, scientists had to undergo the same procedure I did in my college ecology lab: hours and hours of microscope identification, which obviously in a professional setting incurs a big financial consequence as well.

To run their test, the team analyzed 90 samples of diatoms taken from different rivers in Switzerland and determined their ecological status using the Swiss diatom index (DI-CH). They then used their taxonomy-free approach, as they call it, which involves a molecular index based on DNA sequences that all diatoms have, to compare the accuracy of the results. And it worked! The taxonomy-free method gave a correct assessment for 77% of the examined sites!

"The whole range of DNA sequences revealed in each sample corresponds to a specific DI-CH quality index. Furthermore, each sequence identified has a different distribution and is detected in variable amounts from one sample to another. By integrating all these data, we were able to calculate an ecological value for each sequence, without having to identify the species to which it belongs," explains Laure Apothéloz-Perret-Gentil, author of the study. The hope is that the molecular index created for diatoms could be adapted for other bioindicators, allowing an even more comprehensive (and speedy) analysis of river and stream health.

This new system is not, of course, without fault. “Its main limitations,” explains the study, “are under-sampling and the need to calibrate the index based on the microscopic assessment of diatoms communities. However, once calibrated, the taxonomy-free molecular index can be easily standardized and applied in routine biomonitoring, as a complementary tool allowing fast and cost-effective assessment of the biological quality of watercourses.”

Sources: ScienceDaily, Molecular Ecology Resources

About the Author
  • Kathryn is a curious world-traveller interested in the intersection between nature, culture, history, and people. She has worked for environmental education non-profits and is a Spanish/English interpreter.
You May Also Like
OCT 08, 2020
Immunology
Air Pollution Particles Detected in the Placenta, Immune Cells Mop Them Up
OCT 08, 2020
Air Pollution Particles Detected in the Placenta, Immune Cells Mop Them Up
Tiny, black particles much like those found in polluted air have been found in the placentas of pregnant women, as repor ...
OCT 18, 2020
Earth & The Environment
Pandemic-enforced lockdowns cut premature deaths from air pollution
OCT 18, 2020
Pandemic-enforced lockdowns cut premature deaths from air pollution
A new study published in The Lancet Planetary Health reports that pandemic-enforced lockdowns in China and Europe h ...
OCT 23, 2020
Chemistry & Physics
The Ever-Evolving Battle to Fight Corrosion in Nuclear Reactors
OCT 23, 2020
The Ever-Evolving Battle to Fight Corrosion in Nuclear Reactors
Since its birth in the early 20th century, atomic research has brought mostly positive impacts to our lives. This week i ...
NOV 03, 2020
Cell & Molecular Biology
The Connections Between Toxins, Genes, and Disease
NOV 03, 2020
The Connections Between Toxins, Genes, and Disease
We are exposed to a vast array of chemicals every day. Many are harmless or even important, like the air we breathe, wat ...
DEC 02, 2020
Earth & The Environment
How will the continents come back together again?
DEC 02, 2020
How will the continents come back together again?
New research presented at the annual meeting of the American Geophysical Union highlights the future of our continents & ...
DEC 08, 2020
Earth & The Environment
Geothermal plume discovered under Greenland
DEC 08, 2020
Geothermal plume discovered under Greenland
Two new studies published in the Journal of Geophysical Research recently provide the newest update on the state of ...
Loading Comments...