Tests of ocean chemistry and climate effects

The NOAA GO-SHIP prior to departure from Brazil. Credit: Melissa Miller

A team of graduate students and researchers from the University of Miami is sailing the North Atlantic Ocean on an international research trip to learn more about how the ocean changes over time.

The team of 11 ocean researchers and seven students, as well as one graduate student, from the Rosenstiel School of Marine, Atmospheric, and Earth Science and the Cooperative Institute for Marine and Atmospheric Studies (CIMAS) joins scientists from 15 organizations across the country. The team of about 60 scientists is collecting water samples from various depths and locations in the Atlantic to gain insight into how the ocean’s chemistry is evolving as water temperatures rise.

The cruise is part of the GO-SHIP project, which seeks to track the transformation of our oceans as a result of climate change.

“This is one of the most important climate change projects that these two agencies are involved in,” said Chris Langdon, a professor of marine biology and ecology at the Rosenstiel School and one of the principal investigators of this cruise. “About 25 percent of all the carbon dioxide emitted into the atmosphere each year dissolves in the ocean, and it’s critical to know if that amount is changing because the earth would be warmer today if the oceans weren’t absorbing so much carbon dioxide.” .

On the 274-foot-long Ronald H. Brown, which is the largest vessel in NOAA’s fleet, scientists and students collect water samples at 24 different depths about every 60 miles along the same latitude in the Atlantic Ocean. As part of the program, they make the same trip about every 10 years, according to Leticia Barbero, an associate scientist at CIMAS and NOAA’s Atlantic Oceanographic and Meteorological Laboratory, and one of two lead scientists for the current trip, which lasts from March to May.

In fact, Barbero is also one of the lead researchers for all US-based GO-SHIP cruises. He pointed out that the voyages are critical because the data gathered on the ship helps scientists worldwide understand how — and at what rate — the oceans absorb carbon dioxide. While the world’s oceans absorb between 25 and 33 percent of carbon dioxide from the atmosphere, that amount could be declining over time, he noted.

“We want to know how much human-produced carbon is being stored in the ocean, and where it’s going in the ocean. And we want to assess that decade by decade,” said Barbero, a chemical oceanographer who focuses on tracking the movement of carbon dioxide. . “We’re also looking at how the ocean’s temperature and oxygen concentration have changed. This is important because seawater has dissolved oxygen into it, which fish and other organisms in the ocean use to breathe. And some parts of our oceans have dangerous low oxygen concentrations today.”

The journey began in early March when the research vessel left Suape, Brazil, for the equator and then turned north to travel across the Atlantic. In April, the ship will stop in Spain for refueling and then continue along a set latitude to its destination in Reykjavik, Iceland.

Langdon—who studies how ocean chemistry affects marine life, especially coral—sent a team of graduate students and scientists aboard the massive research vessel, but trained them in Miami and Brazil before the trip. With the help of scientists on board, his team will use the ship’s Large Conductivity, Temperature and Depth Sampler, or “CTD,” to collect ocean water around the clock. Specifically, they will measure dissolved oxygen, pH and total alkalinity in the water.

“It’s an ideal way for students to be exposed to this field, and a lot of the things they’ve learned in their classrooms related to climate change come from data collected on these trips. So they can make connections to what they learn in the classroom,” said Langdon, who has been on several research cruises, including one that sampled ocean water along the east coast of North America and others in the Gulf of Mexico and the Antarctic Ocean. “The way I “The way it works is that the water collection instruments are lowered over the side of the boat by a cable, then the students do real-time chemical analysis and have six hours to measure it before doing it again.”

While one of Langdon’s graduate students, Emma Pontes, has attended three research cruises in the past, graduate candidate Riley Palmer is going for the first time. Palmer will be on board for the entire two-month voyage and said she is looking forward to expanding her field research experience.

“This is a unique opportunity that most people don’t have access to, so it will be good for my career and personal development,” Palmer said. “I’m also excited to get more comfortable with the water chemistry bench application and see what other labs are doing on board.”

A trend that has been noted on many of the GO-SHIP voyages is that as the oceans warm, the water’s pH levels drop – meaning it becomes more acidic, according to the scientists. In the early 2000s, Langdon was one of the first to discover the critical importance of pH in ocean water to sustaining marine life. And the more acidic the seawater, the harder it is for calcifying marine organisms to thrive. This is an unfortunate phenomenon that Pontes has seen firsthand in her research with Langdon.

“Ocean pH is going down, and that’s a huge problem for corals, clams, shellfish and anything that forms a shell or skeleton of calcium carbonate,” Pontes said.

At this point, for the first time on this cruise, according to Barbero, scientists will also collect ocean water samples to explore their biological, environmental DNA.

“I’m really curious to see what comes of it,” she said. “This will be our basis for looking at the distribution of organisms along the ship’s path by looking at the DNA. We can then correlate this with environmental measurements such as temperature, oxygen concentration and depth to understand why there are certain concentrations of specific groups of plankton. for example, in a given area — and then we can see if they’re still there in 10 years.”

The team will also deploy ARGO floats, which are instruments that collect seawater underwater and periodically send data back to shore.

Throughout the frenzied analysis of water samples, however, there will likely be some incredible moments, Pontes said. On previous voyages she has seen dolphins, pods of pilot whales and other marine life around the ship. This time he hopes to see an ocean sunfish or a killer whale. However, the aspiring research scientist also understands the importance of travel.

“We need to monitor what’s happening in our oceans, and these are some of the only long-term, comprehensive datasets of the world’s oceans,” Pontes said. “These are really good tools for monitoring changes in ocean chemistry, especially with the effects of climate change.”

Provided by University of Miami

Reference: Testing Ocean Chemistry and Climate Impacts (2023, March 16) Retrieved March 16, 2023, from https://phys.org/news/2023-03-ocean-chemistry-climate-impact.html

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