Now let’s turn to a question that you can explore:

How does marine life recover from a major, one-time stress such as an oil spill?

Mearns Rock is located in the intertidal zone on Knight Island in Snug Harbor, Prince William Sound, Alaska. Here is how it appeared in 2003, 14 years after the Exxon Valdez oil spill. (Photo credit: OR&R, NOAA)

As you have learned, the answer is not simple. The Mearns Rock Time Series is a series of photographs of "Mearns Rock," a large boulder (approximately 4 feet high by 7 feet long) located in the intertidal zone at Snug Harbor on Knight Island, Prince William Sound, Alaska.

Find the location of Snug Harbor using the trajectory map.

On March 24, 1989, the Exxon Valdez veered out of the normal tanker channel and struck Bligh Reef in Prince William Sound, releasing nearly 11 million gallons of oil. The map shows the oil front as it expanded from 1 to 8 days after the spill. (Map credit: U.S. Geological Survey)

The boulder is located on a very protected, south-facing rocky shoreline that was oiled during the Exxon Valdez spill in March 1989. This section of shoreline was not cleaned after the spill. Scientists believe that the boulder, like the rest of the shoreline, was coated by spilled oil, which was gradually removed by natural processes during the year following the spill. NOAA biologists have photographed this boulder—and the animals and plants growing on it—once each year, in late June or early July, for the past 14 years. Look at the map on the right to see how the oil spread in Prince William Sound for the first eight days after the spill and answer this question: How many days after the spill occurred did oil reach Knight Island, the location of Mearns Rock?

Here is your chance to work with some real data collected by real scientists. Using photos of Mearns Rock, you can graph changes over time in the percent cover of different organisms that have colonized the rock since the Exxon Valdez spilled its oil. You will be working like NOAA scientists, including the scientist for whom the rock is named—Dr. Alan Mearns.