Understanding the Ocean’s Role in Absorbing Carbon Emissions

Research cruise tests new technologies

As humans continue burning fossil fuels, much of the carbon emitted into the atmosphere eventually makes its way into the ocean. This past fall, the University of Rhode Island research vessel R/V Endeavor embarked on a week-long cruise on which scientists undertook research designed to help them better understand how the ocean traps carbon.

One study suggested that the ocean has absorbed up to 48 percent of carbon dioxide emitted from fossil fuel burning between 1800 and 1994.¹ The increasing levels of carbon in the ocean have led to other problems, such as ocean acidification. The process of carbon absorption in the ocean is an important aspect of understanding the progression and impact of global climate change.

Melissa Omand, a new faculty member at the URI Graduate School of Oceanography, headed the cruise, which looked at several factors related to the movement of carbon on the edge of the Outer Continental Shelf, about 100 miles south of Rhode Island’s coast. The location is known as a very productive area for phytoplankton, which are microscopic organisms that absorb carbon dioxide. Additionally, this location is at the edge of a network called the Pioneer Array—a series of instruments that have been deployed by the National Science Foundation to make long-term measurements in the area as part of a project called the Ocean Observing Initiative, which provides researchers free access to a wide range of data collected from oceans around the world.

RV Endeavor bosun Oscar Sission helps Marine biologist Colleen Durkin, from Moss Landing Marine Lab in California, to recover the gel sediment traps.

R/V Endeavor bosun Oscar Sisson, left, helps marine biologist Colleen Durkin, from Moss Landing Marine Lab in California, to recover the gel sediment traps.

This cruise focused mainly on examining how carbon moves from the atmosphere through photosynthesizing organisms and sinks into the oceans through the physical movement of seawater. Understanding this process is of particular concern in light of global climate change, Omand explains. “Right now there are major global strategies being developed … on the basis of, for example, IPCC (UN Intergovernmental Panel on Climate Change) models,” she says, referencing computer modeling systems used to predict future climate change.

Omand’s team also looked at the process for carbon export known as the biological pump. This process describes how tiny specks of carbon-containing material known as “marine snow” sink down through the ocean. Marine snow is the carbon absorbed by phytoplankton at the surface, which then sinks down through the ocean as the organisms die, or is released as tiny fecal pellets. This marine snow can be captured using sediment traps, which consist of cylinders that are sent down to capture the sinking particles at various depths.

URI marine research assistant Roger Patrick Kelly assists with recovery of the Wirewalker, a wave-powered device designed at Scripps Institution of Oceanography to gather data at different ocean depths.

URI marine research assistant Roger Patrick Kelly, right, assists with recovery of the Wirewalker, a wave-powered device designed at Scripps Institution of Oceanography to gather data at different ocean depths.

Testing new methods of collecting data was an important part of Omand’s cruise. One of the new pieces of technology was a holographic microscope, used to capture pictures of phytoplankton. This piece of equipment allows researchers to view phytoplankton as they move through the ocean, instead of having to take a sample and bring it back to a lab. Noah Walcott, a graduate student working under Omand, explains the process this way: “The advantage of holographic microscopes is that anything that’s in the field of view can be focused on. So unlike [a normal microscope], where you have to be able to focus it manually in order to take pictures, with a holographic microscope you simply capture whatever’s in the viewing plane and then you focus it [at a later time].”

Gel sediment traps were another new technology used on the cruise. These traps also capture marine snow, but unlike traditional sediment traps, they keep the particles separated instead of just collecting them all at the bottom. This is helpful because they preserve the size of marine snow particles, which affects the rate at which they sink, and in turn how quickly carbon is stored in the ocean.

Omand is glad to have had the opportunity to be part of the Endeavor program. “It’s a pretty special thing that it’s even possible to get this ship time for doing these kinds of pilot experiences at URI,” she says. “Ship time is really expensive, and it’s hard to get.” Whereas most programs require a much more extensive process with more rigid requirements, she says that the relative flexibility of the smaller Endeavor program is an important resource in allowing Rhode Island researchers to test new ideas and technologies. “[The Endeavor program] is supporting these pilot efforts … I think that’s pretty unique.”

Use of “telepresence” revolutionizes the research cruise

This cruise was significant for another reason too: this was the first time that a URI cruise was conducted by a chief scientist who was actually on shore. The use of telepresence—a communications system that allows audio and visual communication via satellite—itself is a fairly new initiative at URI. The recently installed telepresence system on the Endeavor has been used on only four cruises, including Omand’s. However, the other three cruises used telepresence as a way to broadcast to shore. This technology came in handy for another purpose with this cruise though: the scheduled date for the trip ended up being just a few weeks before the date that Omand’s first child was due.

Instead of being forced to call off the trip, or at least having to step down from a leadership role, Omand was able to lead the cruise from the Inner Space Center on URI’s Bay Campus. Colleen Durkin, a researcher from Moss Landing Marine Lab in California who was part of Melissa’s team on the cruise, noted, “I think it was pretty awesome that being pregnant didn’t stop her from this really important part of her career. [It was] her first time as chief scientist, and I think it’s pretty awesome that URI found a way to still enable her to do that.” Omand was impressed by how well the experience went, and said that despite intermittent dropped connections, she was pleased that she felt that she could always get in contact with the ship.

The telepresence had other benefits as well. It was connected to a YouTube feed that the public could access, including friends and family of many of those onboard, which received over 4,600 views. It was also used for troubleshooting—when the holographic microscope began having connectivity issues midway through the cruise, research assistants onboard were able to connect to the manufacturer in Nova Scotia to try to figure out the issue. Using a GoPro camera hooked up to the telepresence equipment, the manufacturer was able to watch what the team was doing as they disassembled the microscope. “He was able to walk us through step-by-step,” said Walcutt. “That was extremely helpful … it’s a sensitive piece of equipment, so we wanted to make sure we were doing everything properly.” Meg Estapa, a scientist from Skidmore College who was Omand’s second in command, said, “This is definitely one of the most connected cruises I’ve ever been on … It’s nice to have that ability to access knowledge and resources onshore.” Usually, she explained, what you bring with you on the ship is all you have to work with.

The telepresence found yet another use when a group of Girl Scouts came to tour the Inner Space Center. Durkin had collected a sample of plankton with a net tow earlier that day, and was looking at it under a microscope when the tour came through. “While they were asking me questions we brought the GoPro over to the computer screen, which had a camera hooked up to the microscope, so they could actually see the plankton sample while they were talking to me,” she recalled. “That was really fun! I didn’t expect them to be so excited … They had a lot more questions than I expected them to.” She remembers the first time she saw plankton though a microscope as the moment that she really became interested in pursuing science as a career. “Hopefully they had as exciting an experience as I had the first time I looked through a microscope.”

1. http://news.nationalgeographic.com/news/2004/07/0715_040715_oceancarbon_2.html

By Keegan Glennon | Rhode Island Sea Grant Communications Intern