What can a bucket of water tell us about Arctic marine life? A lot, says a new study

Scientists have proposed a new technique to monitor the impact of climate change and human activity on marine life

By DTE Staff
Published: Wednesday 13 January 2021

The surface of the Arctic Ocean, the planet's northernmost waterbody, is frozen most of the year. But under this thick sheet of ice thrives a diverse ecosystem much of which has eluded marine biologists because of the lack of accessibilty. 

A group of researchers from the University of Copenhagen, Aarhus University and the Greenland Institute of Natural Resources are trying to bridge this information gap using the simplest of tools — a bucket.

In a study published in Environmental DNA on January 7, 2021, they have said seawater samples collected in buckets or bottles can provide crucial insight into how the marine ecosystem has been impacted by climate deviations and human interference. 

The scientists set sail in small boats in Disko Bay, West Greenland and collected pails of seawater teeming with 'environmental DNA', or eDNA. They took help from local hunters and fishermen to carry out the study. 

Of the DNA samples they found, the researchers focused their analysis on the bowhead whale, key species of the Arctic megafauna. The report said its “distribution, abundance, life history, and health are tightly connected to sea ice and sea temperature”. 

“This way, we are able to keep an eye on how humans and climate changes impact the bowhead whale and other marine life in the Arctic,” said Morten Tange Olsen, associate professor of marine mammals, University of California and instigator of the study. 

In 2017 and 2018, the scientists collected around 135 samples in the month of May when these whales swim to the sea surface through the freshly-opened cracks in the ice. They suggested in the report that samples should be collected in the 'footprint' or ripples formed by the travelling sea animals, or from transects, to best capture their genetic diversity. 

Back in the laboratory, they extracted the DNA of the bowhead whales from the different seawater samples, amplified and sequenced them to study the quantity and quality present in each. 

Their key observation was that the amount of bowhead whale DNA was 15‐fold higher in the footprint of a diving whale compared with water samples collected during transect surveys.

“Moreover, we found that bowhead whale DNA could be detected in footprints for at least 10 min after the dive, providing a short window of time in which to obtain population genetic data,” the report said. 

Based on these findings, they proposed this technique for cost-effective and fast collection of genetic information and monitoring changes on marine lifeforms not just in the Arctic but also in other aquatic ecosystems. 

“Given the ease of collecting environmental samples for eDNA analysis, we see a great potential in involving and training local communities in routine sampling for a community‐driven genetic monitoring network,” the authors noted in the report. 

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