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Ocean Acidification: Understanding Changing Chemistry in Alaska Coastal Waters

Region(s) of Study: U.S. States and Territories / Alaska
Primary Contact(s): kris.holderied@noaa.gov

This project began in January 2010 and was completed in December 2012

Ocean acidification is a problem created by the increasing levels of carbon dioxide in our atmosphere, and it is harmful to certain plankton, shellfish, coral, and marine plants. We have begun a pilot study in Kachemak Bay, Alaska, to measure the variations in acidity that result from freshwater input from glaciers, snowmelt, and rainfall and from upwelling ocean water. The bay’s unique geographic features provide a cost-effective way to study varying acidity levels.

Why We Care
Coastal Alaska waters face more immediate threats from ocean acidification than anywhere else in the global ocean because of the low pH of the northern Pacific Ocean and the effects of cold water on ocean chemistry. Ocean acidification is the ocean’s response to increased carbon dioxide levels in the atmosphere. As the oceans absorb more carbon dioxide from the air, the pH of the water decreases and the oceans become more acidic. The ocean is already 30 percent more acidic than it was before the start of the industrial age, and changes in water chemistry will have a global impact. Higher acidity in ocean water is harmful because it:

  • Weakens the shells of clams, oysters, and mussels, as well as coral skeletons
  • Damages the small plankton that can make up half the diet of some salmon species in Alaska
  • Reduces growth or causes death during the sensitive, early life stages of crabs and other shellfish
  • Changes the growth of valuable habitats, such as seagrass, kelp, and coralline algae.

The possible consequences are alarming and could adversely fish and shellfish species that are a vital source of food, a key component of the Alaska economy, and an integral part of Alaska Native cultural traditions. Fishing is a $5.8 billion industry and generates 78,500 jobs in Alaska’s economy. The Gulf of Alaska is at elevated risk because it is where cold, deep waters that are rich in nutrients, but also low in pH, are upwelled at the coast. The cold temperatures also result in greater acidification than do warmer waters.

What We Are Doing
We are conducting a pilot ocean acidification monitoring project in Kachemak Bay, Alaska. The bay is a large, biologically rich estuary with freshwater input from glaciers, snowmelt, and rainfall and upwelling of ocean water from the Gulf of Alaska. The Bay provides a unique opportunity to cost-effectively measure the variability in acidity caused by these factors. Since ocean acidification measurements are being made by NOAA and university researchers in adjacent ocean waters, we are also investigating linkages between coastal and open ocean waters.

By quantifying, for the first time, the natural variability of ocean acidification with the system, we are determining the consequences of increasing ocean acidity. The measurements are also providing the information needed to place sensors for future long-term monitoring of acidity. We’ve begun measuring changes in the water chemistry of the bay to:

  • Understand links between near-shore and ocean conditions
  • Assess how coastal species will react to potentially corrosive, acidic waters
  • Provide context for future studies on species response to increasing acidification
  • Guide development of future estuary acidification monitoring systems.

We’re also conducting surveys during different seasons to determine the temperature, salinity, carbon content, and pH in surface and deep waters. We’re analyzing oceanographic variability and collecting water samples to send to researchers at the University of Alaska Fairbanks School of Fisheries and Ocean Sciences to analyze carbonate chemistry and pH. These coastal acidification measurements will also be coordinated with ocean acidification monitoring done in the open ocean waters of the Gulf of Alaska by NOAA researchers with the Office of Oceanic and Atmospheric Research’s Pacific Marine Environmental Laboratory and National Marine Fisheries Service’s Alaska Fisheries Science Center and by university researchers, allowing us to see how the increased acidity affects both coastal and open-ocean ecosystems.

Next Steps
Ultimately, we will use the pilot project results to design an ongoing estuary acidification monitoring program to:

  • Monitor acidification trends in Alaska coastal ecosystems
  • Predict how acidification in coastal waters will change in the future
  • Understand how those changes may affect growth and survival of coastal resources and habitats.

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