Longest-ever eDNA study offers important insights into ocean health

Longest-ever eDNA study offers important insights into ocean health
Sampling for plankton and eDNA using a net. Credit: IMOS-CSIRO/Julian Uribe

Tiny genetic 'breadcrumbs' left behind by marine organisms offer unprecedented insights into ocean biodiversity and how it changes over time and in response to our changing climate, new research at Curtin University, in collaboration with CSIRO, has revealed.

Researchers developed new environmental DNA (eDNA) biomonitoring methods using samples collected off the coast of Rottnest Island near Perth, Western Australia, as part of Australia's Integrated Marine Observing System (IMOS).

IMOS scientists collected and froze filtered seawater samples over a five-year period. These 'time capsules' provided a unique opportunity to study changes in our oceans and that occur seasonally and in response to climate anomalies such as the marine heatwave that struck WA in 2011.

The study, published in journal PLOS Genetics, demonstrated how a zooplankton community – the larvae and eggs of fish – responds normally to seasonal change in contrast to heatwave conditions.

The study is the longest multi-year marine eDNA study yet conducted and showcases the power of eDNA technologies to monitor our health.

Ph.D. student Tina Berry and Professor Michael Bunce, from Curtin's School of Molecular and Life Sciences, led the research team.

"It is incredibly rare to find a series of samples from such a long time period that are also suitable for DNA analysis," Ms Berry said.

"The scientists at IMOS had the foresight to biobank a set of samples that allowed us to travel back through time and see how the ocean responded to a marine heatwave.

"After some in the lab to isolate and sequence the DNA, a significant and revealing story appeared. The end result was a holistic window into our marine life that would otherwise be impossible to see."

Professor Bunce said environmental DNA was fast emerging as an effective way to study our oceans and the technique hit the headlines in 2018 as researchers went searching for the Loch Ness Monster using eDNA.

"We didn't find any monsters either, unless you count two samples with trace amount of humpback whale in them. But to be honest, it's the small creatures that live in our oceans that provide the greatest clues to our ocean's wellbeing."

Professor Bunce said the eDNA signatures mapped out which were present at different times of the year and identified those that first appeared when sea surface temperatures spiked during the heatwave.

"Being able to track thousands of marine species at a time using eDNA offers important clues regarding how our oceans are changing as they warm, it's a glimpse into the future that we can't see using other methods," Professor Bunce said.

"Australia has the Earth's third largest ocean territory and every year the nation derives an estimated $47.2 billion from its 'blue economy' so understanding how it is changing is of high national importance.

"Using eDNA, we are detecting sharks, corals, seahorses and marine mammals and the DNA toolkit we are developing in our wider research program is a road-map for long-term ocean monitoring around the world. We urgently need better ways to perform health-checks on our marine environments and eDNA is responding to this need."

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eDNA analysis—a key to uncovering rare marine species

More information: Tina E. Berry et al. Marine environmental DNA biomonitoring reveals seasonal patterns in biodiversity and identifies ecosystem responses to anomalous climatic events, PLOS Genetics (2019). DOI: 10.1371/journal.pgen.1007943
Journal information: PLoS Genetics

Provided by Curtin University
Citation: Longest-ever eDNA study offers important insights into ocean health (2019, February 12) retrieved 15 October 2019 from https://phys.org/news/2019-02-longest-ever-edna-important-insights-ocean.html
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Feb 12, 2019
At best this will be a baseline snapshot of the time period covered and any changes going forward; unfortunately there are no parts of the oceans, the continents, the atmosphere, or anywhere else on the planet life might have been found historically that can be said to be untouched by our pollutants, the invasive species we have shuffled from place to place, or the gaps created by the unknown numbers of native species we have caused to go extinct. The general disturbance of geochemical and biological processes that we humans have wrought in our few thousand years rising to our current position as disruptors during the Anthropocene can only be adapted to now, going forward. We can bring our activities under control if we choose to do science in the name of sustainability, but we won't be able to recreate the "natural" past our ancestors once found everywhere they looked because we will never be able to fully sample its characteristics scientifically. It is gone.

Feb 13, 2019
... we won't be able to recreate the "natural" past our ancestors once found everywhere they looked because we will never be able to fully sample its characteristics scientifically.

The survey is long but in a small volume, c.f. the much wider and nearly equally long Tara Ocean project.

Seems to me that we now know enough that there never was a steady baseline, humans or not involved. And kudos for air quoting "natural" since today is the new natural and/or its history is irrelevant for what we want it to be.

That we and our cows (and to lesser degree other farm animals) are now crowding out other populations is a problem. Re the survey that says even many insects [!] are going (though of course they are often patchy specialists in nature). On the other hand surveys now say the new "natural", cities, are the best sources for animal and planet diversity around (no doubt also an effect of breaking up areas into patches), also unexpected.

Feb 13, 2019
air quoting "natural"

Idiomatically, in colloquial English, to "air quote" something necessitates the physical use of two fingers on each hand held up in the "air" to the sides of the person's head who is then said to be "air quoting" whatever he or she is saying while making that gesture. As I cannot tell if you are being facetious towards my comment, but know for a fact that you couldn't see the position of my hands when I typed it, perhaps you were looking for the term "scare quotes" instead? I wasn't using the marks in that manner either but since you did not rate my comment the ambiguity is only reinforced.
My position: There is no dividing line between humans and nature. We are an evolved, biotectonic process, increasingly proving Ardrey correct when he said we were,
"... evolutionary failures, trapped between earth and a glimpse of heaven, prevented by our sure capacity for self-delusion from achieving any triumph more noteworthy than our own sure self-destruction."

Feb 14, 2019
Well dudester, I don't think your nym is to be read colloquially either. Somewhat facetious since I couldn't know if you meant your quote to weaken the naturalistic fallacy or not.

Few or no species manage their own extinction (I can't think of an example), but all species goes extinct. But the question of baseline or what we want during our species lifetime was not about that, see my previous comment.

I had to do some googling to see who [Robert] Ardrey refer to, Apparently a playwright (with paleontology training) dabbling in commenting on biology, and someone evolutionary scientists have deemed "totally and utterly wrong". Which apparently upsets some people for reasons I do not know. [No links, since those sites were as prone to think their readers know the intended context and the reason why they personally has a burr up their ass as you are. References, please!] Anyway, not a biologist.

Feb 14, 2019
My fault, reading more I note Ardrey was a practicing scientist later [ https://en.wikipe...t_Ardrey ]. Seems to be the among the people who implied humans is an aggressive specie, which we are not, which upset in view may explain the upset around Ardrey.

Feb 15, 2019
Some have hypothesized that vast numbers of anaerobic forms of life contributed to their own widespread destruction, if not outright total extinction, some 2.5 billion years ago by bioprocessing various oxygen containing compounds for other elements and then releasing the oxygen as a waste product. This gas eventually built up in the environment which in turn made the environment toxic to those very forms of life leading to the extinction of up to 99% of all life on earth at that time. It remains a hypothesis of course, but a credible one.

To claim that our industrial processes which release various greenhouse gasses as well as too many thousands of toxic compounds to name, which then interact with one another in the laboratory of the world leading towards as yet unimaginable punctuation events for ourselves and all other forms of life on earth are different somehow from what those ancient microbial "polluters" did, buys into the naturalistic fallacy. Human industry is natural.

Feb 15, 2019
Dawkins called Ardrey "totally and utterly wrong" because Ardrey suggested that group level selection can and does occur, as do E. O. Wilson and his group. Most who criticize Ardrey have not read him. Steven Pinker quoted 'The Selfish Gene' verbatim about Ardrey in 'The Blank Slate', before destroying Montagu and Lewontin and even Steven Jay Gould for their erroneous reliance, ultimately, on Rousseau's blank slate concept of nearly unlimited plasticity in human behavior. Yet he didn't even know that Ardrey had done in Rosseau et al 30 years earlier presaging many of Pinkers own arguments in his 1970 book 'The Social Contract'.

Did Ardrey make mistakes? Of course. His chronology was off, as was everybody's then and as ours probably still is. Did he overemphasize the idea that the ancestral ape was a cunning hunter? Probably. But if you can read Darwin and forgive him for not knowing about genes or DNA, you should at least read Ardrey before accepting the criticisms of him by others.

Feb 15, 2019
I recommend Ardrey's 'African Genesis', 'The Territorial Imperative', and 'The Social Contract', all of which I have read. I own his 'The Hunting Hypothesis' but haven't read it yet as I know it is the weakest portion of his argument-- and yet of course it is the one work of his on which his opponents focus.
Ardrey graduated Phi Beta Kappa from the University of Chicago with a degree in anthropology. He became a close friend of Robert Ardrey, a person who also suffered the indignity of a "scientific consensus" that his ideas about the strange little fossils of hominids he had discovered in South Africa were deemed "totally and utterly wrong" because "scientific consensus" preferred to accept the large cranium and human-like teeth of the Piltdown hoax until that hoax was exposed-- because those authorities wanted to think the human brain came before the human dentition.
Btw, almost all animals are aggressive when they need to be. By the same measure most can also be cooperative.

Feb 15, 2019

Obviously Ardrey didn't become a close friend of himself. I meant, in my last comment, that he of course became a close friend of Raymond Dart.

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