All living beings, from man to microbes, have DNA in their bodies. They also keep shedding bits of the material into the environment. Scientists have now hit upon the idea of collecting this environmental DNA, or eDNA, in the depths of the seas to identify what lives there — a simpler method than having to go down there to study.

Stories are seeping out of scientific journals about how scientists are using eDNA to survey biodiversity in rivers, lakes and oceans. Apart from giving a biodiversity picture, such study could also yield early clues to invasive species.

eDNA can also reveal the presence of human remains. Scientists have collected samples of seawater from the vicinity of a plane wreck — the American aircraft was shot down near Japan during the Second World War — to look for floating eDNA.

(For more on DNA extraction, see ‘Chennai start-up makes DNA extraction easy’.)

Conservation efforts are predicated upon monitoring, which has traditionally meant the physical identification and counting of species. Imagine doing this over thousands of square kilometres under the seas! Technologies such as Quantitative Polymerase Chain Reaction (qPCR) determine whether the eDNA in a sample corresponds to a particular species. Scientists believe that eDNA, coupled with DNA sequencing, can pinpoint what lies beneath.

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