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.
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.
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.
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.
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.
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.
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.