Mearns Rock 2001

What You See

This year, the boulder has a 20%-30% cover of Fucus. Older (brownish) plants are visible on the left section of the boulder and younger (greenish-brown) plants on the right. A whitish "bald" patch on the upper left is actually a patch of barnacles. Another bare-looking patch on the lower right corner contains barnacles (white) and small mussels (dark spots). A bright green algae, possibly "sea lettuce" (Ulva) droops down along the lower third of the rock face. Algae and barnacles also cover most of the cobble on the beach face.

What's Happening

During the early 1990s, marine plants and animals covered most of the boulder. Then, almost everything other than mussels disappeared by 1994. Later, the cycle of new life started up again in 1995 and 1996. We thought this might be part of a four to five year-long cycle of colonization, growth, and death. However, in 2001, six years later, the cover of marine life has not disappeared nearly as completely as it did in 1994.

So what's going on? Perhaps, over the past 12 years, intertidal marine life here has experienced variability that is decreasing with time. We may never see the boulder (and the shoreline) go bare again as it did in 1993-94. On the other hand, other things happened in the late 1990s that had not occured in the early 1990s, including the pronounced 1997-98 El Niño. Perhaps the El Niño led to local conditions that prevented plants and animals from dying off in the late 1990s, as they did in 1993-94. How would an El Niño do this?

(07.01.01, Snug Harbor, Knight Island, Alaska)