DNA in seawater can reveal the diversity of fish in the deep ocean

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A camera trap baited with fish at a depth of over 2000 meters. Credit: David Cote, Fisheries and Oceans Canada

New study demonstrates the effectiveness of a new method of using DNA in seawater samples to determine which species of fish are present in a given part of the deep sea. A team of scientists from eDNAtec Inc. and colleagues from Fisheries and Oceans Canada and Memorial University present these results in the open access journal PLOS ONE November 4.

The ability to monitor the diversity of deep-sea fish is necessary to implement sustainable management efforts and understand the impacts of commercial fishing and climate change. However, existing methods such as baited camera traps, trawling, and acoustic monitoring have limited detection capabilities and are difficult to use in much of the ocean.

A new method called eDNA metabarcoding reveals which fish are present in a given habitat by analyzing environmental DNA (eDNA) – DNA that is shed by organisms in the surrounding environment during their normal activities.

To assess the effectiveness of eDNA metabarcoding for the detection of deep-sea fish, McClenaghan and his colleagues applied it to seawater samples taken from the Labrador Sea at depths of up to 2,500 meters. In deep water samples (depths of 1,400 meters or more), eDNA metabarcoding identified 11 families of fish, 11 genera and 8 species. The researchers compared their electronic DNA metabarcoding results to those obtained by conventional methods and found that they offered wider coverage of the diversity of fish and other taxa while using much less logistical effort. These advantages make eDNA techniques an important advance for large-scale surveillance applications.

The research team also explored eDNA metabarcoding using varying volumes of deep seawater samples and different DNA primers – short strands of DNA applied in laboratory analysis of the DNA to determine which species are present. Their results suggest that the deep ocean environment requires some adjustments to methods used in shallower water, such as using larger volumes of water and using multiple primers to maximize species detection.

While the authors plan to further refine electronic DNA metabarcoding procedures for the unique nature of the deep sea environment, they note that this method may already provide important information for monitoring fish diversity. in the deep ocean.

The authors add: “Advances in genomics and computational tools are rapidly expanding our ability to study and monitor biodiversity, an indispensable task in the face of rapid and sweeping environmental changes. Our study demonstrates the utility of electronic DNA analysis for the difficult surveillance effort. species of fish in the deep ocean and sets the stage for the adoption of this approach by various stakeholders. “


Using DNA to research fish species


More information:
McClenaghan B, Fahner N, Cote D, Chawarski J, McCarthy A, Rajabi H, et al. (2020) Harnessing the power of eDNA metabarcoding for the detection of deep-sea fish. PLoS ONE 15 (11): e0236540. doi.org/10.1371/journal.pone.0236540

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Citation: DNA in Seawater May Reveal Fish Diversity in the Deep Ocean (2020, November 4) Retrieved November 5, 2020 from https://phys.org/news/2020-11-dna-seawater -reveal-fish-diversity.html

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