Scientists on an Australian Antarctic Program voyage to the Denman Glacier region in East Antarctica are trialling new ways to understand biodiversity, without the need to disturb marine creatures.
On board Australia's icebreaker, RSV Nuyina, Australian Antarctic Division geneticist Dr Leonie Suter is collecting environmental DNA (eDNA) from seawater samples during the Denman Marine Voyage, to build a picture of the biodiversity in the region.
eDNA is DNA shed by all organisms into the environment, allowing scientists to identify what organisms were in the water around the time a sample was taken.
"If we take a small seawater sample, we can filter that and then sequence the DNA to tell us what's living there," Dr Suter said.
"It's a way to do a biodiversity survey from just a small water sample, without ever having seen any of the animals. We can infer what's living there from the genetic traces that are left behind, and we can do that from surface water, but also throughout the water column all the way down to the seafloor."
During the two-month voyage Dr Suter is collecting five-litre surface water samples, three times a day, through the ship's seawater line. She is also collecting water samples from different depths using RSV Nuyina's Conductivity, Temperature and Depth (CTD) instrument.
"The surface and CTD samples will give us a three dimensional picture of biodiversity," Dr Suter said.
"And if we do this sampling repeatedly, as part of a long-term monitoring program, we can look at whether biodiversity is changing over time, and which ocean variables are influencing community compositions."
Key to this long-term monitoring program could be some new technology Dr Suter is trialling during the voyage, in collaboration with the Monterey Bay Aquarium Research Institute (MBARI) in California.
"We have two automated eDNA samplers that will plug in to the seawater line and automatically filter the water at pre-determined times throughout the voyage," Dr Suter said.
"Later we'll compare the results from the manual and automated systems to see if we can use the automated system on future voyages."
Dr Jim Birch, Director of the SURF Center at MBARI, said the Environmental Sample Processor (ESP) and the Filtering Instrument for DNA Observations (FIDO) could collect 60 and 144 water samples, respectively.
"Both instruments filter water and preserve whatever is on the filter in a way that allows the sample to sit unrefrigerated for two to four months," Dr Birch said.
"You can schedule the instrument sampling times on a phone or computer and they're very simple to operate."
The ESP has been used on ships, "autonomous surface craft", and elsewhere in the northern hemisphere. However, this is the first time FIDO has been deployed in the field, and the first time for both instruments in the southern hemisphere.
"This is an engineering test for us - will these devices work autonomously over 10 weeks with very little human interaction?" Dr Birch said.
"We're really excited to see how they perform."
Dr Suter said she is ready to "expect the unexpected".
"There are a lot of unknowns on this voyage," she said.
"But these tools will help us learn more about the baseline diversity and describe the environments that we're encountering in the different regions of the Southern Ocean."
Dr Suter is one of 60 scientists on board RSV Nuyina, spending two months using the ship's marine science capabilities to investigate critical climate questions about the glacier's accelerated melt rate, factors influencing it, and the regional and global impacts.
Learn more in our digital feature Nudging a sleeping giant.
The Denman Marine Voyage is a collaboration between the Australian Antarctic Division, the Australian Centre for Excellence in Antarctic Science (ACEAS), the Australian Antarctic Program Partnership (AAPP) and Securing Antarctica's Environmental Future (SAEF).
