Key points
- A multinational research team has completed a milestone scientific mission to Antarctica aboard CSIRO research vessel (RV) Investigator.
- Researchers collected data, specimens and samples from the ocean surface to the seabed and below to better understand the impact of climate change on the Cook Glacier marine region, a little studied area in East Antarctica.
- During the voyage, RV Investigator passed the milestone of spending the equivalent of one full year at sea supporting Antarctic science to increase our understanding of this significant and fragile environment.
Navigating monolithic icebergs, massive ocean waves and sub-zero snowstorms, CSIRO research vessel (RV) Investigator is a workhorse for Antarctic science. In just over 11 years and spread across 7 voyages, the vessel has now spent the equivalent of one full year, or more than 10 per cent of its time, at sea delivering crucial research in Antarctic waters.
Let’s break the ice on our latest milestone Antarctic mission.
RV Investigator navigated massive icebergs and heavy seas during the 55-day voyage in Antarctic waters. Image: CSIRO-Hanuman Crawford.
Investigating the Cook Glacier marine region
This summer’s voyage to the icy waters of East Antarctica, also known as the COOKIES voyage, set out to unlock the mysteries of the marine area off the Cook Ice Shelf. Globally significant yet little studied, this remote region holds clues to how Antarctica has responded to past warming and what that might mean for its future.
Over 55 days at sea, a multinational team of researchers, led by scientists from the University of Tasmania’s Institute for Marine and Antarctic Studies (IMAS), travelled more than 6,500 nautical miles (12,000 kilometres) to uncover those hidden clues.
By studying how ice, ocean and life interact in this region, scientists are piecing together a clearer picture of how changes in Antarctica can ripple across the globe.
Checking out a million-year archive
Antarctica stores a layered record of global change in its seafloor sediments. Each layer of sediment is like a page in a history book.
Voyage Chief Scientist, Dr Linda Armbrecht from IMAS, said scientists can analyse this natural archive to reconstruct how Antarctica responded to warming periods in Earth’s past. Those insights help scientists predict what may lie ahead.
“Sediment cores, simply imagined as tubes of mud, are collected from the seabed and act as time capsules,” Dr Armbrecht said.
“The uppermost layers record the last few centuries, while deeper sediment cores can reach back hundreds of thousands, even millions, of years. Within those layers are fragments of ancient DNA, microfossils, rocks and chemical clues that reveal what the ocean once looked like – from temperatures and currents to changes in the ice sheet and life in surrounding waters.”
The COOKIES science team was led by Dr Laura De Santis (PM shift leader), Dr Linda Armbrecht IMAS (voyage Chief Scientist) and Dr Jan Strugnell (AM shift leader). Image: Joline Lalime.
Working from the bottom up
Throughout the voyage, CSIRO technicians collected high resolution seabed mapping, called bathymetry, and mapped the layers of sediment beneath the surface using RV Investigator’s suite of multibeam echosounders.
Less than 30 per cent of the global seabed has been mapped to a modern standard, meaning each square kilometre surveyed adds valuable new seabed information, expanding our understanding of ocean floor structure and composition.
This mapping guided researchers to the best places to sample the seabed sediments. Using RV Investigator’s range of coring systems, the voyage team worked tirelessly to recover a library of sediment cores, short and long.
Adding to a voyage of milestones, the team achieved a record retrieval for RV Investigator’s giant piston corer with a 20.5 metre-long tube of sediment recovered from the seabed.
In total, the voyage returned with more than 10,000 sediment samples to be analysed back in the laboratory for ancient DNA (aDNA), microfossils, sediment geochemistry and more.
On a milestone voyage, the COOKIES team also recovered a record length sediment core for RV Investigator at 20.5m. Image: Michael Watson.
Underway sampling delivers vital ocean information
Understanding how Antarctica is changing means studying the environment as a complete system – not just the seabed, and not just the surface, but everything in between.
The underway sampling systems on RV Investigator operate around the clock at sea to collect vital information from the ocean, atmosphere and seabed everywhere the vessel travels. Soon after leaving port, the ship’s systems began building a picture of surface waters by collecting underway seawater samples as the vessel made the long journey south across the Southern Ocean.
“Each sample offered a glimpse of what was living in the water at that moment – microscopic algae, tiny drifting animals, and even traces of organisms detected only through the DNA they leave behind,” Dr Armbrecht said.
By voyage end, more than 130 water samples had been collected for plankton, environmental DNA (eDNA), microbial and diatom analysis. These samples help the team track how life and chemistry shift across thousands of kilometres of open ocean.
To see what was happening below the surface, researchers lowered the CTD (conductivity, temperature and depth) instrument that traces the ocean’s biological, chemical and oceanographic structure all the way from surface to seabed.
These measurements revealed how layers of warm and cold-water stack, mix and move, and how those layers shape the conditions that life depends on. Water collected in the ring of sample bottles – called Niskin bottles – around the CTD allowed scientists to measure the nutrients that act like vitamins for marine ecosystems.
Researchers busily collect water samples from the CTD instrument in the CTD Laboratory onboard RV Investigator. Image: Joline Lalime.
“Small changes in the ocean, whether in temperature or nutrients, can lead to big changes in ocean productivity and ecosystem function,” Dr Armbrecht said.
“In addition to the CTD, we deployed a trace metal rosette, a specialised instrument to collect water samples for trace metal analysis that help us understand the fundamental chemical and physical processes driving the ocean.”
As their name suggests, trace metals such as iron, zinc, manganese and copper, are only available in tiny amounts in the ocean – but are essential for life to exist. They are a limiting factor in the growth of phytoplankton, which are the foundation of the ocean food web. As such, trace metals play an important role in ocean productivity.
Together, the observations collected on the voyage will help scientists understand where carbon and nutrients are absorbed and stored, how water masses interact, and how changes at the surface ripple down through the ocean’s depths – all essential pieces of the climate puzzle.
Cataloguing Antarctic biodiversity and finding stranger things
Researchers on the voyage weren’t only interested in the open ocean.
Ecological surveys were conducted on the Antarctic continental shelf using RV Investigator’s cameras and sleds. The vessel’s Deep Towed Camera was deployed to survey benthic (seafloor) ecosystems rarely observed by human eyes. Benthic sled sampling operations were then conducted to collect marine life for identification and study.
Elegant underwater, researchers found this soft coral was considerably more unsettling when out of the water. Image: CSIRO.
Tunicates, a type of animal commonly called sea squirts, form a field of ‘glass tulips’ on the Antarctic seafloor. Image: CSIRO.
Resembling coconuts on the Antarctic seafloor, a group of glass sponges provide shelter for fish and other marine life. Image: CSIRO.
Researchers were able to document around 400 organisms from their sampling operations, with further materials collected for DNA analysis. More than 10,000 still images were also captured from the Deep Towed Camera, along with many hours of video footage for biodiversity analysis.
“When combined with the ocean data, these biological surveys unlock more chapters of the story of Antarctica. Together, they offer clues to the resilience of Antarctic ecosystems,” Dr Armbrecht explained.
It all counts when it comes to the science
The numbers matter. The voyage samples and data represent years of analysis to come. Fieldwork is only the beginning. Painstaking laboratory work by researchers, as well as current and future students, will now carry the science forward and deliver information to generate knowledge to inform future management and research.
Andrew Martini, Program Director with the CSIRO Marine National Facility, explained that it marks steady progress in unlocking one of the most consequential and least understood environments on the planet.
“Despite the years of research, Antarctica remains a place of unanswered questions and each voyage reveals just how much more there is to discover,” Mr Martini said.
“For the global scientific community, RV Investigator’s voyages to Antarctica offer vital access to one of the most important climate laboratories on the planet. The knowledge gained ultimately benefits us all, providing us with a better understanding of changes that affect oceans, climate and life on Earth.”
The superstructure of RV Investigator is silhouetted by green and red light from the aurora australis or ‘southern lights’ during the return voyage from Antarctica. Image: CSIRO-Hanuman Crawford.
This research was supported by a grant of sea time on RV Investigator from the CSIRO Marine National Facility. The research contributes to various collaborative Antarctic research programs and is supported by the Australian Centre of Excellence in Antarctic Science (ACEAS) and Securing Antarctica’s Environmental Future (SAEF).