An unprecedented life experience in the middle of the ocean

By Umair Mumtaz, University of Western Australia

Today is the last day of the CAPSTAN research voyage IN2019_T01. My excitement is palpable as CAPSTAN has surpassed my expectations. The training provided in multidisciplines ranging from geology, geophysics, oceanography and microbiology will definitely act as a milestone for stepping into a future marine scientist. Time passes so quickly, I spent almost 12 days in the ocean and during these days I observed nature very closely, clear water, blue sky, sea birds and micro organisms with in the ocean.

CAPSTAN students Angela (left) and Umair (right) work together to take discrete sediment samples from the kasten core and place them in a small plastic sample bag as part of the hands on marine science training on RV Investigator during the 2019 voyage
Here, we take discrete samples from the kasten core in the sediment lab (Photo Credit: April Abbott)

This year’s training cruise was targeted on the canyon system on the eastern edge of the Bight Basin, near the outer continental shelf just southeast of Portland, Victoria. This region is unique due to the presence of cool water carbonate turbidite deposits. Such carbonate systems can only be formed with minimal terrestrial input. I was enthusiastic to see these carbonate systems as my masters research project is also related to the carbonates but they are formed in warm and temperate environment.

A bathymetric map of the canyon off Portland Victoria studied as part of hands-on marine science training on RV Investigator during CAPSTAN 2019.  Overlaid on the bathymetric map is color depicting the steepness of the slope with warm colors showing the steepest regions and cool colors showing the less steep regions.
Map of the canyon near Portland showing slope steepness (red is steepest)

Carbonate involves limestone and dolomite (rocks) that consists of mineral calcium carbonate (CaCo3) and dolomite CaMg(Co3)2 respectively. The organisms that live with in the water are zooplanktons (animals) and phytoplanktons (plants). They are made up of calcium carbonate and after their death they accumulated with in the water and after cementation and compaction, limestone is formed. It is important to understand carbonates because they can tell us about sea level changes, paleoceanography, paleoclimates, and marine ecosystems. They also holds around 50% of the oil and gas reserves.

View down the microscope of foraminifera, a sponge spicule, and other coarse grain material from a sieved sediment sample students collected from a kasten core as part of hands-on marine science training on RV Investigator during CAPSTAN 2019
A close up of some of the carbonate sediments we collected. In this view down the microscope, several foraminifera (phytoplankton) are visible. (Photo Credit: April Abbott)

A submarine canyon is a steep sided valley that extends from continental shelf to the sea bed. The turbidity currents carry material from the continental shelf passes through the canyon with an immense speed and may deposited with in the canyon and deep ocean floor. There can be many driving forces behind these turbidity deposits. These can be triggered by earthquake, gravity flows and tectonic forces. Due to density contrast between the sediments, the coarser ones will deposit first and finer will remain in suspension and deposited at the end.  

CAPSTAN 2019 Chief Scientist Leah Moore motions with her hands to illustrate how a rock dredge collects samples during a gear tour on board RV Investigator for students participating in the at-sea hands on marine science training program
Chief Scientist Leah Moore explains the rock dredge during a gear tour (Photo Credit April Abbott)

Our chief scientist, Dr. Leah Moore selected specific depths for coring after looking at the bathymetry (geophysical) data. The bathymetry data uses acoustic (sound) waves to determine the geomorphological features of the ocean floor. The RV Investigator is equipped with the Kongsberg EM122 multibeam echosounders to retrieve high quality bathymetry maps. The cores were retrieved at 1700m, 2200m, 3700m and 4700m depths. I was working in the sedimentology lab to find out the variations in percentage of the fossils present in the top and bottom of each core. I was exposed to using the microscope to identify different foraminifera.

CAPSTAN students collect water from the niskin bottles surrounding the CTD rosette as part of hands-on marine science training on board RV Investigator.
Taking water samples from the niskin bottles attached to the CTD rosette (Photo Credit: April Abbott)

Another exciting thing was CTD as it was new for me. CTD stands for conductivity, temperature and depth. It consists of a carousel that has 36 niskin bottles with sensors at the bottom. In the operations room, a fluorescence curve that shows the chlorophyll activity with in the ocean and helps to decide the locations for samples. These bottles were closed at designated depths while coming back to surface. The polystyrene cups that were decorated by the students were sent down with the CTD to demonstrate the pressure affect. These polystyrene cups became very small in size after coming back from the ocean. Due to this small experiment, it is very easy to understand that pressure increases with depth.

Styrafoam cups shrunken to about the size of a shot glass can be seen in a pile in an onion bag.  These cups were sent kilometers below ocean and the pressure shrunk them from their original size.
Polystyrene cups after being sent down with the CTD are seen here in an onion bag (Photo Credit April Abbott)

On the very last day, we had a lot of fun. Our CAPSTAN director, Dr. April Abbott arranged a quiz to entertain all the participants and crew members. Everyone was in a different costume except me to relish those last moments. Our trainer, Stephen is a great geologist but his sense of humour was also amazing. I am obliged to be a part of this exciting opportunity as it not only increased my knowledge related to marine science but also helped me to thick critically, improved my confidence and science communication skills.

CAPSTAN trainers sit in the RV Investigator's mess looking at a laptop while discussing data students collected as part of the hands on marine science training voyage.
CAPSTAN co-chief scientist Matt (left) and trainer Stephen (right) discuss the results from the sedimentology lab in the mess
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