Tuesday, November 21, 2017

NOAA Research Cruise Aims to Dissolve Uncertainties of Ocean Acidification

Friday, September 13, 2013

by Leslie Irwin, OAR Office of Communications

CTD rosette

CTD rosette

Crew member, Jeff Kesler on board the Fairweather prepares for CTD rosette deployment, which will measure conductivity, temperature and depth. while collecting water samples. Credit: NOAA
The ship rocked as someone maneuvered the winch to bring the cable with the submerged sensors and water samples back on board the Fairweather, watched by three other researchers to ensure a smooth return. Eight researchers eagerly waited on deck for their portion of the samples, contained in 24 bottles containing water from different depths.  The self-described “sample cop,” Dr. Erica Ombres maintained what can only be considered organized chaos, and distributed the samples to the crowding scientists, each of whom would examine a different parameter to help paint the larger picture of ocean acidification and its effects.

“Although scientists were on this mission to better understand how ocean acidification affects ecosystems on the west coast, a research vessel is like an ecosystem unto itself once it leaves port and gets underway,” explains Ombres. “It takes many people working together to keep the boat on course, everyone on board safe and to collect quality scientific data,” recalling the captain, crew, engineers, stewards and scientists from the cruise last August. Led by NOAA’s Pacific Marine Environmental Laboratory (PMEL) scientists Dr. Richard Feely and Dr. Simone Alin, NOAA’s Ocean Acidification Cruise ran from Seattle, WA down the west coast to Moss Landing, CA.

Buoy and Ship

Buoy and Ship

The Cape Elizabeth ocean acidification monitoring buoy with Fairweather in the fog nearby, as viewed from a small boat deployed from the larger ship. Credit: NOAA

Why go through all this trouble? The excess carbon dioxide (CO2) in the atmosphere from burning fossil fuels is absorbed by our oceans, and this changing ocean chemistry could affect important ecosystems and fisheries. Increased levels of CO2 cause an increase in acidity (or decrease in pH) that can affect a variety of organisms, particularly those with calcium carbonate shells or skeletons (i.e. shellfish, corals, plankton) sensitive to corrosion. The shellfish industry of the Pacific Northwest alone contributes around $111 million a year into the region’s economy, bringing jobs to over 3,200 people, primarily in coastal communities.

"It is high time to realize that changes in our marine ecosystems are already underway, and there is no point in denying the fact that our CO2 emissions are impacting all of us."

Even though the CTD rosette (conductivity, temperature and depth sensor) could measure many parameters in real time, scientists confirmed these measurements by also testing the water samples back in their labs. They tested the water’s oxygen levels, salinity, alkalinity, pH, carbon, and collected samples of phytoplankton and zooplankton, all of which are critical to understanding the process and effects of ocean acidification. Separate net sampling at each sample site collected tiny pteropods, a type of marine snail with a calcium carbonate shell highly susceptible to ocean acidification effects. As a primary food source for economically important fish like cod and salmon, the future of pteropods in an increasingly acidic ocean environment could have serious implications.

Sampling nets

Sampling nets

Ben Moore-Maley directs the operation of the bongo nets, which are towed behind the ship and collect pteropods for sampling. Credit: NOAA

“We are very excited to have the opportunity to examine these animals over such a range of conditions, and we expect the results of these studies to have broad implications concerning the impacts of ocean acidification on the pelagic food web," says Ben Moore-Maley, a master’s student at the University of British Columbia.

The sampling mission occurred around the clock, so scientists and crew had to devote their full attention during 12-hour shifts during the day and night. The timing and location of sample sites for the cruise was determined by the West Coast upwelling season, which occurs along the California Current that runs from British Columbia to Baja, California.  This upwelling causes deep, cold, CO2-rich water to rise toward the surface near the coast, causing a natural ocean acidification event.

The results from the cruise will shed light on ocean acidification effects that are happening right now, as well as what we can expect to see in the future if CO2 emissions continue to rise.

Observing pteropod respiration

Observing pteropod respiration

Dr. Nina Bednarsek observes pteropod respiration rates with a closed-cell cuvette oxygen sensor. Credit: University of British Columbia

Nina Bednarsek, a Post-doctoral fellow with PMEL, hopes to raise awareness of the affects we can already see.

“I believe that it is high time to realize that changes in our marine ecosystems are already underway, and there is no point in denying the fact that our CO2 emissions are impacting all of us.”

If making sure that happens requires a ship with a crew, scientists, and engineers, a little bit of seasickness, and around-the-clock shifts and sampling deployments, then that’s what they will do.

To learn more about how the scientists and crew lived and worked on board for the cruise, check out the Ocean Acidification Cruise Blog!



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