Wednesday, October 22, 2014

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BIOLOGICAL RESPONSE APPROACH

Laboratories at three NOAA National Marine Fisheries Service Science Centers conduct experiments to determine how economically and ecologically important species respond to ocean acidification. State of the art experimental facilities were recently completed at the Northwest, Northeast, and Alaska Fisheries Science Centers.  All facilities can tightly control carbon dioxide and temperature. The Northwest Fisheries Science Center can also control oxygen, and can create variable treatment conditions for all three parameters. These facilities maintain chemistry analytical laboratories and use standard operating procedures for carbon chemistry analysis to characterize the treatment conditions used in experiments.

Experiments that explore how species survival, growth, and physiology are impacted by ocean acidification give scientists an understanding of how free-living species may respond to ocean acidification. NOAA researchers use these data to explore how aquaculture, wild fisheries, and food webs may change as ocean chemistry changes.

NOAA scientists conduct experiments on a wide variety of species, ranging from phytoplankton to fish.

CURRENT EFFORTS

NOAA Led Study Shows Walleye Pollock Resilience to Ocean Acidification

Scientists at NOAA’s Alaska Fisheries Science Center recently found that some life history parameters of walleye pollock seem to be only minimally affected by high CO2 waters. Dr. Thomas Hurst and University of Alaska colleagues Elena Fernandez and Dr. Jeremy Mathis conducted multiple experiments in conditions mimicking both present day CO2 levels in high latitude waters and those predicted to occur over the next century (280-2100µatm, pH= 7.4- 8.16). They measured the rate at which walleye pollock eggs hatched as well as their size when they hatched, along with larval survival, size, and growth rates. In elevated CO2 waters, time-to-hatch was slightly longer, but no decrease in size at hatch was measured. The researchers observed a trend toward larger body size in the higher CO2, low pH waters, but this result was not statistically significant. Because varied responses were observed among experimental trials, it is possible that egg and prey quality as well as characteristics of the foraging environment of the parental brood stock may have affected experimental outcomes.

The results of this study highlight the importance of examining other natural or human-induced factors that can affect an organism’s response to changes in pH, while also considering a species’ ability to adapt to these changes. Although the direct effects of ocean acidification on the physiological parameters of larval walleye pollock measured in this study were minimal, this critical resource species may be indirectly impacted by the responses of their food sources (i.e., krill, zooplankton, and other crustaceans) to high CO2 conditions. These impacts will likely be important factors in dictating future pollock populations, one of the largest single-species fisheries in the U.S.

This research was funded by the Pollock Conservation Cooperative Research Center, the Rasmuson Fisheries Research Center, Oregon State University’s Hatfield Marine Science Center, and NOAA's Alaska Fisheries Science Center and Ocean Acidification Program.

photo of walleye pollock

Walleye pollock.  Photo credit: Alaska Fisheries Science Center