May 25, 2019 | Updated: 09:32 AM EDT

Detection of Coral Reef State Made Available Through eDNA Technology

Apr 18, 2019 08:45 AM EDT

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Coral Reef Thriving with Fish
(Photo : Pixabay)

University of Hawaii researchers have developed a new method for measuring the amount of living coral on a reef by analyzing DNA in small samples of seawater. Patrick Nichols, a graduate student in the marine biology graduate program, and Peter Markon, an associate professor in the Department of Biology are the researchers who published their findings in Environmental DNA.

Coral reef ecology usually use underwater visual surverys for coral reef monitoring. Current visual methods like SCUBA consume a lot of time and requires high levels of logistics. 

All organisms shed DNA into the environment. This eDNA or environmental DNA can be analyzed to complement visual surveys to determine species diversity in aquatic environments. 

It has long been accepted that eDNA can identify the presence and absence of species. However, there had no been study that is substantive to show the relationship between the quantity of DNA and the abundance of organisms. The new method developed by Nichols and Marko show that it is a cost-effective and quick way of determing live coral "cover." Cover is the area of coral reef inhabited by living corals. Coral cover is an important parameter in characterizing the status of a reef since corals influence the presence of other species that thrive on it.

"It still amazes me that in a tiny tube of water, there is enough information to track the relative abundance of entire communities," said Nichols. "Increasing the breadth and scope of surveys is exactly what makes the future of eDNA so exciting!"

The researchers utilized metabarcoding which involves the analysis of all the DNA in a water sample in one step with DNA sequencing. The abundance of different kinds of corals at each reef is determined by the identification and counting of the coral DNA sequences. A very minute amount of eDNA implies a degraded reef while a stronger coral eDNA amoung signifiies reefs with more living corals.

"The authors explain in their paper that this new technique can be used to track changes in coral reef health and community composition over time, as well as detect rare species that can otherwise be missed by traditional visual-based survey methods," according to Phys

"If you asked me 10 years ago if this was possible, I would have said, 'No way,'" said Marko. "But advances in technology and falling costs of highly-sensitive DNA sequencing methods have opened the door to all kinds of important ecological questions."

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