For Dr Julie Janssens, being a sea-faring scientist wasn’t always top of her list of dream jobs. However, Julie has now spent a total of over a year at sea on various research vessels doing just that.

Julie’s journey to high seas scientist

Julie originally graduated with a Masters in bio-engineering from Brussels, Belgium. She then completed a PhD in Antarctic sea ice at the Institute for Marine and Antarctic Studies (IMAS).

“During my PhD I got super lucky, and I went to Antarctica by boat a few times,” Julie said.  

“The first time was part of my PhD. I was sampling the sea ice, brine and seawater for biogeochemical and trace metal analysis.

“These were big sea ice voyages. I will never forget the magic of seeing my first penguins, first ice bergs, first whale, aurora and pancake ice, and bigger ice floe. From there, I was hooked,” she said.

Julie is now a senior hydrochemist with our specialist Engineering and Technology team that support the Marine National Facility (MNF), operator of research vessel (RV) Investigator. Hydrochemistry – study of the chemical composition of natural waters – is just one group in this team. The team offers world-leading expertise to deliver technical and operational solutions for the marine community, including our researchers.

Julie is living the marine scientist dream, sharing her time on shore and at sea. She works in the Hydrochemistry Lab on board RV Investigator, studying the ocean as part of wider research programs. 

Hydrochemistry 101

Hydrochemistry is study of the chemical composition of natural waters. Three water parameters are vital in gaining a basic understanding of an ocean’s movement, health and ecology. Julie and our hydrochemistry team specialises in measuring all of these. Accurately and precisely. 

First is salt. Or, more accurately, salinity – the amount of salt in seawater. Measuring salinity allows us to ‘finger-print’ and track water masses. Salinity also provides an insight into whether the world’s oceans are becoming fresher or saltier as the climate changes. 

Second is oxygen. Dissolved oxygen is a key measurement for understanding how well marine life can survive in the ocean. It plays a large role in fish health. 

Third is nutrients. Often called the building blocks of life, nutrients are made up of dissolved inorganic macro nutrients. These nutrients are nitrate, nitrite, phosphate, silicate and ammonium. They are the primary food source for the ocean’s smallest organisms, phytoplankton.  

Accurate measurement of these nutrients in seawater provides biologists with important data of the food available in the ocean. It also indicates where the food is coming from. 

Julie and our hydrochemistry team can accurately measure these parameters down to very, very low levels. For both ocean and coastal waters. The hydrochemistry team operates from laboratories in Hobart and Perth, as well as on the RV Investigator, supporting research across Australia. 

Sea to CTD

To collect sea water for analysis, hydrochemists use an instrument called a CTD. This is a fundamental tool for ocean science and has sensors that measure ocean conductivity (C), temperature (T) and depth (D). 

The circular frame of the CTD also carries a rosette of bottles – either 24 or 36 bottles. The team uses these bottles (called Niskin bottles after their designer, Shale Niskin) to collect water samples from different depths in the ocean.  

The caps on the bottles are left open when the CTD is deployed. The caps are programmed to snap closed at specific depths to collect water samples for analysis. 

Both 24 and 36 bottle CTDs can be deployed from RV Investigator to depths of 7000 m. 

“As you might imagine, it’s incredibly busy when the CTD comes back on board. Any free hands are always welcome to don some gumboots and gloves and help us collect the samples,” Julie said. 

A sense of community

Julie says working on a research vessel at sea can be a very busy job. However, almost every day is rewarding and brings new experiences. Even after eight voyages on RV Investigator – and counting!

“I love meeting new people and learning new things from the voyage participants. On biodiversity surveys, I really enjoy the samples the scientists bring onboard. Some creatures are quite funny looking,” Julie said.

“I also love experiencing the amazing community we form on long remote voyages.” 

Julie’s tip for an indispensable luxury item on those long voyages?  

“Belgian chocolate and my pillow. That’s two things but I swear I equally can’t do without them!” 

Learn more about the work of marine scientists and the amazing technology used to study our oceans at the One Ocean-Our Future exhibit. The exhibition is open at the Australian National Maritime Museum in Sydney from 1 December 2021 to 31 October 2022.