NOAA’s 20th Annual Survey of Prince William Sound, Alaska, Reveals "The Year of the Mussel” and Other Interesting Trends
Mearns Rock – named for the NOAA scientist who has studied the effects of the Exxon Valdez oil spill in Prince William Sound, Alaska, for the past 20 years – is a large boulder, about 4 feet high by 7 feet long, located at Snug Harbor on Knight Island in the sound. It sits on a protected rocky shoreline that was oiled during the spill in March 1989 but was not cleaned. The spilled oil gradually dispersed on its own. NOAA researchers have photographed Mearns Rock, and the plants and animals that reside on it, every year, in late June or early July, for the past 20 years. Note how life on Mearns Rock has changed over the decades, a natural process that has helped scientists better understand how life ebbs and flows in the intertidal zone.
At the end of June, two NOAA employees made their annual trek to Prince William Sound, Alaska, for the 20th year in a row. Alan Mearns, a Seattle-based scientist at NOAA’s Office of Response and Restoration, and John Whitney, NOAA’s Scientific Support Coordinator for Alaska, conducted the 20th annual survey of the western portion of the sound, where the Exxon Valdez tanker made infamous environmental history on March 24, 1989. The single-hulled, 300-meter-long vessel ran aground on Bligh Reef in the previously pristine sound, spilling nearly 42 million liters (11 millions gallons) of crude oil.
The spill killed outright at least a quarter-million seabirds, 2,800 sea otters, 300 harbor seals, 22 orcas (killer whales) and other marine mammals, and billions of eggs of salmon and herring. It also injured some 2,100 kilometers (1,300 miles) of shoreline and hurt local industry, communities, subsistence livelihoods, and tourism.
Mearns and Whitney check for lingering oil deposits, take photos, observe shorebirds and other wildlife, and record data on a variety of shoreline fauna, including mussels and other shellfish.
Mearn’s work focuses on long-term trends in marine life that inhabits the intertidal shoreline, which is the region between the points of high and low tide. “The plant and animal life in the rocky intertidal area recovered, within the range of natural variation, within three to four years,” he notes, “but our longer-term program has revealed that clams at oiled and cleaned beaches required 10 years to recover, and that the seaweeds, mussels, barnacles, and other dominant species undergo five- to seven-year cycles of boom-and-bust productivity.”
“Had we not continued monitoring for this long, we would be under the false impression that intertidal shoreline life reaches a predictable and stable ‘climax’ community,” Mearns continues. “But it does not. In fact, I would call 2009 ‘The Year of the Mussel.’ The last time mussels were dominant features was in 2002-2003 and 1993-1994.”
“With increased understanding of climate change, including ocean acidification, this type of shoreline monitoring needs to be continued indefinitely, not only in Prince William Sound, but all around the U.S. coastline,” he concludes.
For the third year, Mearns and Whitney also worked on a project funded by NOAA’s Marine Debris Program. In previous summers, Whitney has been involved in efforts to remove “mountains” of debris from Prince William Sound. The debris drifts or blows into the sound from the North Pacific, much of it from many of the same shorelines that were oiled by the Exxon Valdez spill 20 years ago. As a result, the scientists have established marine-debris monitoring sites that are relatively close to the Exxon Valdez monitoring sites. This allows other people and boats to join and assist NOAA with its monitoring efforts.
The Exxon Valdez oil spill was a landmark environmental event that raised people’s awareness of the havoc that oil spills can wreak on marine ecosystems. The disaster ultimately had a positive effect, however, because it was a catalyst for the Oil Pollution Act of 1990, which continues to engender improvements in spill preparedness, response, and restoration.
In addition to NOAA scientist and team leader Alan Mearns, who took the photo, this year's Prince William Sound monitoring crew and volunteers included (left to right) John Bauer, retired from the Alaska Department of Environmental Conservation; John Coombs, owner of the P/C Wave Walker; John Whitney, NOAA's Scientific Support Coordinator for Alaska; Bill Heiberger, an oil company retiree; Chris Pallister, a Gulf of Alaska Keeper; and Will Frost of the Alaska Department of Fish and Game.