Pollock Conservation Cooperative Research Center
2009 Awarded Research Projects
Project Title: Present and future impacts of ocean acidification on juvenile walleye pollock metabolic processes and growth rates
Principal Investigator: Jeremy Mathis
Award: $56,793
Abstract
The ocean plays a critical role in the global carbon cycle: the amount of carbon stored in the ocean is roughly 50 times greater than that in the atmosphere. At the surface, the ocean interacts constantly with the atmosphere to absorb and release carbon dioxide. Once absorbed, a carbon atom will remain in the ocean for hundreds of years, circulating from the ocean's surface to its depths and back to the surface again. With the rise of atmospheric CO2 concentrations from the pre-industrial level of 280 parts per million to 385 parts per million in 2008, the amount of carbon in the ocean has increased substantially and rapidly. This carbon dioxide has combined with water to form carbonic acid, making ocean surface water 30 percent more acidic on average. Depending on the extent of future CO2 emissions and other factors, the Intergovernmental Panel on climate change (2007) predicts that ocean acidity could increase by 150 percent by 2100.
Potential impacts of ocean acidification on harvested species like pollock are uncertain. One area of concern is acidosis, or the build-up of carbonic acid in body fluids, which can disrupt growth, respiration and reproduction. Despite our lack of knowledge, the trend of ocean acidification is undeniably concerning, especially considering the devastating consequences that acid rain had on freshwater ecosystems during the 20th century. Furthermore, the ocean is currently undergoing other potentially dangerous changes, including warming, sea level rise, pollution and overfishing. The rapid pace at which these changes are occurring, and the fact that they are happening simultaneously, threatens to disrupt the ocean's well-balanced physical, chemical and biological processes faster than they can adapt. Changes in ocean pH may have an affect on reproductive success and early development of pollock in the marine environment. This could lead to devastating effects on the economic viability of this important fishery as well as the ecosystems of the Bering Sea and Gulf of Alaska. Decreasing pollock stocks could have a cascading impact through the food web, affecting the sustainability of higher tropic level organisms like the Steller Sea Lion. In order to gain some insights into this area we propose to answer the following questions; (i) Does acidification show a significant effect on standard metabolic rate of larval pollock? (ii) Which metabolic enzymes (PK, LDH, and CS) does ocean acidification significantly effect, and how? (iii) What is the current and future state of ocean acidification in the Gulf of Alaska and in the Bering Sea, particularly in areas of pollock recruitment? Our hypotheses for this study are that; (i) There will be a significant increase in the standard metabolic rate of larval pollock when exposed to lower pH. (ii) There will be a significant upregulation of metabolic enzymes as the environmental pH decreases. (iii) In the past two decades the pH of the World's Ocean has dropped by 0.1 – 0.25 pH units. It is likely that a similar drop in pH has occurred in the Bering Sea and Gulf of Alaska. Increasing levels of atmospheric CO2 will likely exacerbate this problem during the next decade and beyond. This project will combine laboratory analyses of pollock incubated at lower pHs as well as the synthesis of pH data throughout the Bering Sea and Gulf of Alaska. The project will be conducted by Elena Fernandez, a Master's student at UAF who worked on a similar project involving lyre crabs which produced some startling results.
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