Friday, July 31, 2015

Alaska Ocean Acidification Monitoring Network

One of the other exciting bits of scenery we’ve been driving by on this cruise have been our very own buoys! These blue-and-gold surface moorings are the centerpiece of the work done at UAF’s Ocean Acidification Research Center, and are one of our best tools for monitoring Ocean Acidification. (We’re pretty proud of them). On this mission, we’ve visited two of these buoys, one located in Port Conclusion and one just outside of Seward at the entrance to the GAK time series line.  It was dark when we drove past our Southeast buoy, but we got a great shot of GAKOA on a bright sunny day when we visited.
View of our GAKOA buoy as we collected our calibration samples. We'll drive by our Kodiak buoy on the way into port! Photo by Jessica Cross (UAF OARC / NOAA).
There are a variety of autonomous sensors on the buoys, designed to measure basic oceanographic variables like temperature, salinity, dissolved oxygen, and fluorescence (a rough proxy for the amount of phytoplankton in the water), as well as sensors that allow us to track pH and the amount of carbon dioxide in the surface water. When we drive by, we’re collecting discrete water calibration samples for the autonomous sensors on the buoy. After we analyze the water we collect, we’ll compare it to the sensor data to make sure everything is working fine. Our ship’s underway systems, like the Burkolator, also provide a valuable comparison tool. Because they collect data constantly, we’ll be able to see how things are change as we approach the buoy, and how well the buoy represents the water around it.

Together, all of these sensors let us monitor seasonal environmental changes. During spring, phytoplankton use carbon dioxide during photosynthesis, and we can watch the concentration go down in the ambient water; during winter, mixing and respiration of organic matter (like when bacteria eat the dead phytoplankton) return that carbon dioxide to the water, and we can watch it build up again. Sometimes, large storms push deeper waters that are naturally rich in CO2 up to the surface, and we can see that too! In fact, so can you: the data from all our buoys is posted online through the OARC website. Just click on the photo of the buoy you’re most curious about!
Our curious cruise participants checking out the GAKOA buoy in the sunshine as we took our calibration samples. Left to Right: Patricia Rivera (UAF); Katie Beaumont (Cornell/UW); Natalie Monacc (UAF OARC); Alex Couturier (OMAO); Rachel Kaplan (UAF); Jessica Pretty (UAF); and Caitlin Smoot (UAF).  Photo by Jessica Cross (UAF OARC / NOAA).
Monitoring these signals helps us identify ocean acidification ‘events.’  These are short periods where the water becomes corrosive to carbonate minerals, usually a combination of natural processes that cause CO2 to build up and ocean acidification. It’s important that we be able to collect measurements over long periods of time to watch when these events start and end, and if they crop up year after year at around the same time. We also hope to understand how these events relate to the biology around them, and whether consistent events might consistently impact certain development or life stages for fish and shellfish. 

The Alaska OA buoy network has been in place since 2011, so 2015 is our five-year anniversary! In addition to the three Gulf of Alaska moorings, we also support one mooring in the Bering Sea. While OARC runs the project, we receive support from the State of Alaska, NOAA, the Alaska Ocean Observing System (AOOS), the National Science Foundation, and the North Pacific Research Board.

For more information about the Alaska OA mooring program, check out these links: 

Alaska Ocean Observing System and Alaska Dispatch News highlight the first buoy deployments


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