THIS is a tale of two very different ships, used for quite different research purposes. Yet despite their differences, the impressively sleek and modern RV Investigator and the elderly two-masted Solway Lass are both helping Australian scientists in the quest to better understand our oceans and climate.
While Investigator, a world-class multidisciplinary research vessel, is sampling ocean waters around Australia and New Zealand for clues about systemic changes to the planet’s climate and oceanic circulation, the Solway Lass – a tourist vessel-cum-research platform – is collecting data specifically to monitor the health of the Great Barrier Reef.
Investigator: into the abyss
Off New Zealand’s east coast, at around 170° west longitude and 3 km or so below the surface, lies a body of slow-moving water that began its journey north with a deep dive from the edge of the Antarctic ice shelf.
A research team led by CSIRO’s Dr Bernadette Sloyan has been tracking and measuring this deep current for decades, most recently from aboard the Australian research vessel Investigator, which is owned and operated by CSIRO through the Marine National Facility
Sloyan is about to step down from a nine-year stint as co-chair of an international collaboration known as GO SHIP – Global Ocean Ship-based Hydrographic Investigations Program. GO-SHIP is enabling researchers from many countries to coordinate a global network of hydrographic transects to measure changes in ocean ‘hot spots’, such as the deep western boundary current in the South Pacific east of New Zealand.
The focus of GO-SHIP is the relatively unknown 52 percent of ocean that lies below the top 2000 metres of the water column, which is already patrolled by automated profilers, such as the Argo float network. CSIRO leads the Australian effort to capture ocean data from the ice edge to the equator every 50 km, sampling from surface to sea floor to a depth of 6 km.
The P15S transect, aligned with the 170° west meridian, is particularly important because the deep current here brings oxygen- and nutrient-rich waters from Antarctica to the rest of the world's oceans.
“The higher temperatures and lower salinities that we’ve observed below 2000 metres over the last 30 years have led us back to thinking about what changes are happening in Antarctica,” says Sloyan. The theory is that changes in ocean circulation occurring on the Antarctic shelf due to global warming are directly transmitted to the southwest Pacific basin via the deep western boundary current.
“The temperature changes coming out of the Antarctic are among the largest in the global ocean and are of the utmost importance to the Australian environment and the global climate,” Sloyan notes.
Not only is this deep current getting warmer, it is also becoming fresher and less saline – due to more rapid melting at the ice edge – and is carrying more carbon and less oxygen, both of which have major implications for climate and marine life.
Quality and quantity
Sloyan says GO-SHIP has become a benchmark in oceanographic monitoring due to the quality and reliability of its ship-based data – still considered superior to data collected by automated sampling, due to the presence of scientists on-board as equipment is being deployed.
Thanks to this quality and reliability, CSIRO, Integrated Marine Observing System (IMOS) and other agencies can use GO-SHIP data to calibrate autonomous vehicles like Argo and gliders, in turn improving the quality of data collected by those programs.
“That connection between autonomous vehicles and the high-quality data you get from the ship is really important,” says Sloyan. “As a scientist, I rely all of types of observations – from Argo, ships and gliders – to better understand how the waters of the Pacific and Indian Oceans are working, and how that impacts the Australian and regional climate.”
Investigator itself has played a key role in advancing Australia's research. Sloyan describes it as a ‘step change’ in oceanographic research for the region.
“It’s a magnificent resource,” she says. “The ship design allows it to operate down to the Antarctic ice edge. That’s allowed us to follow P15S, from the ice edge to the equator.
“We can also spend more time at sea and there’s room and facilities to bring together more scientists, from different disciplines, than we were able to with Southern Surveyor (Investigator’s predecessor). Now we have research opportunities that we just didn’t have before.
“Australia is a really important player in Southern Hemisphere ocean research. We’re one of the few countries with a world-class platform that offers us the capacity to bring in other international researchers and drive new observation programs in the Indian and Pacific Oceans.”
Solway Lass: a different tack
Solway Lass, a 116-year-old schooner, has been sailing weekly from Airlie Beach to the edge of the Great Barrier Reef on a 50-nautical-mile odyssey to some of the most scenic beaches on the Whitsunday Islands.
Unlike Investigator, Solway Lass has had a long and colourful career outside of science. Designed and used as a cargo vessel in 1902, before being captured and reclaimed by both Allied and German navies during World Wars 1 and 2, the sailboat was eventually refitted as tourist vessel early this century.
In 2017, a new chapter was added to Solway Lass story, when CSIRO installed automated sensor and data logging equipment to gather data on reef health. The sensors sample air and water conditions every 10 minutes during the ship’s regular trips from coast to reef and back again, sending data by satellite back to CSIRO servers in Brisbane.
According to CSIRO researcher/engineer, Geoff Carlin, who installed and maintains the equipment, the sailboat that began life in a Netherlands’ shipyard over a century ago has now become one of the most sophisticated air and water quality monitoring platforms on the Reef.
Flood plumes
Thanks to Solway Lass, CSIRO has amassed a bank of data on Reef water quality in this region, which can be used by researchers to more accurately calibrate existing models such as eReefs.
Of special interest to scientists – including Carlin – is the question of how sediment runoff and pollution from Queensland’s coast and estuaries changes, both seasonally and over the longer term. After heavy floods, for example, where and how do flood plumes flow out to the Reef?
By intensively sampling transects from coast to reef edge and back, twice a week throughout the year, CSIRO is gathering the sort of high-resolution and high-frequency data that researchers need to answer this question and more accurately predict future flood-plume behaviour.
At the time of writing, Carlin had just returned from a field trip from Queensland’s Capricorn Coast, which suffered a heatwave and devastating bushfires in November.
“We haven’t analysed it fully yet, but when we were out there collecting the data, we could see that after five days of 40-plus-degree air temperatures, we were seeing surface water temperatures beyond healthy reef temperatures.
“What effect would this have on coral bleaching? While answering this is beyond the scope of this project, we’re collecting the type of background data that will help other scientists investigate it later on.”
‘Citizen science’ effect
For Carlin as an engineer, one of the most important outcomes of the study is understanding how a vessel like Solway Lass can be adapted as a Reef research platform without getting in the way of its primary role as a pleasure boat.
“Part of what we’ve done is to improve methods for getting sensors onto these vessels, for longer periods of time between maintenance schedules, but still making sure you get reliable data,” says Carlin.
“I did one trip and gave a bit of a spiel on the system. You could see this ‘citizen science’ effect on the crew and passengers. We’re currently in the process of setting up a video screen so people on board can see the water quality data monitoring live.”
CSIRO is working in collaboration with the Healthy River to Reefs Partnership and Explore Whitsundays.