Imaging the Ocean by Stephanie O’Daly

I'm a PhD student at the University of Alaska Fairbanks and I'm sailing on the A20/A22 US Go Ship cruises. As a part of my research working under Dr. Andrew McDonnell, I'll be deploying an instrument attached to the CTD Rosette called an Underwater Vision Profiler (UVP). This instrument helps us understand carbon cycling in the global oceans, particularly the biological carbon pump. The biological carbon pump is one part of carbon cycling in the ocean where carbon dioxide in transformed into particulate organic carbon (like phytoplankton cells) through photosynthesis at the surface of the ocean. This organic carbon then can be consumed by bacteria or zooplankton or sink to deeper depths through the effects of gravity to deeper depths. Eventually nearly all the particulate organic carbon will be transformed back into carbon dioxide through respiration. However, the deeper the particulate organic carbon can sink in the ocean will result in the longer that carbon is stored away from the atmosphere. Understanding how carbon moves and is stored in the oceans is critical during this time of rapid climate change as a result of anthropogenic carbon dioxide emissions.

The UVP consists of a camera and tiny computer contained within a pressure case that can withstand pressure of up to 6000m of water. Additionally there are lights that illuminate a known volume of water. The camera takes an image every second while the CTD rosette moves down through the ocean to just above the sea floor. The tiny computer identifies where in the image there are particles and saves that information. The UVP tells us information on particle sizes and concentration for particles as small as one tenth of a millimeter up to a few centimeters in length. For larger particles, the computer saves a photo of the particle itself. When I'm back on land I'll use machine learning software to predict and validate particle type. Most particles will be detritus (or dead or dying material), some will be fecal pellets from zooplankton or tiny animals that live in the ocean. I also will be able to identify different types of zooplankton like crustaceans, sea snails, and worms. All of this information helps us better understand how the biological carbon pump functions and help us predict how those functions may change with further climate change.

It's really exciting to be partnered with the US Go Ship project as an ancillary project. It's only through recent improvements in technology that we can collect all of this information without using precious resources like water or time on cruises like the US Go Ship project. I'm looking forward to collaborating with the physicists and chemists who have been working on this project for decades as I'm working with new types of data. Additionally, the US Go Ship program is a great platform for this type of research as it is one of the few programs that samples such large swaths of the global oceans.