What You See

In mid-1991, the entire boulder is covered with the gold-brown seaweed, Fucus, also commonly called "rockweed." You can see darker species of seaweed forming an apron around the base of the boulder; the beach area surrounding the boulder (the "beach face") is also completely covered with other seaweed species. In the water behind the boulder, you can see a healthy eelgrass (Zostera marina) bed.

What's Happening

The boulder's condition appears to be improving, shown by the heavier covering of seaweed. One might conclude that this shoreline had recovered from the oil spill.

What You See

The seaweed Fucus (rockweed) now covers about 20% of the boulder's surface. Large, older plants are gone; they seem to have been replaced by young plants. Mussels are growing on the front face of the boulder (black regions). Although the barnacle areas are difficult to see in the photo, the barnacles have died back considerably.

What's Happening

The young seaweed from the 1990 photo has matured, died back, and has almost entirely left the boulder. The patches of mussels probably began as young animals in 1992 but were too small to be seen in the 1992 photo. Now that they are larger, they are more visible. NOAA biologists aren't sure why the barnacles have died back. Have you any ideas why?

What You See

In mid-1995, about half of the mussels have disappeared, leaving smaller dark regions on the right side of the boulder. The seaweed Fucus (rockweed) is making a comeback on the left side and top surface of the boulder. You can also see a resurgence of algal growth on the beach face.

What's Happening

The disappearance of the mussels may be the result of predation (perhaps by sea otters) or natural mortality. Regardless of whatever caused the boulder's plant life to die back in 1993–94, the boulder now seems to be supporting new plant and animal life.

What You See

The boulder is once again covered (about 80%) with the seaweed Fucus, or rockweed. There are several age groups of Fucus on the boulder. Young Fucus is growing over the top section of the boulder and adult Fucus is growing around the mid-portion. The beach face is again rich with seaweed. No mussels are visible and the areas occupied by the barnacles have shrunk. (Which other photo does the boulder resemble now?)

What's Happening

Starfish and sea otters may have been preying on the mussels, and a predatory sea snail, Nucella, has likely been eating the barnacles. (Although you can't tell from the photo, the Nucella population has been slowly growing on the boulder.)

What You See

You can see that a second crop of Fucus (rockweed), which began to grow in about 1995–96, has matured and now nearly covers the boulder. The larger seaweed that was prominent in 1998 has disappeared.

What's Happening

The mature Fucus plants visible in this photo may be starting to die back. Our observations over the years suggest to us that individual Fucus plants survive for about four to five years.

What You See

This year, the boulder has a 20%–30% cover of Fucus (rockweed). 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 occurred 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?

What You See

This year, the barnacles have died back somewhat, and no new Fucus (rockweed) plants have been established. The Fucus plants that remain appear slightly larger this year. Sea lettuce continues to grow in the lower left corner of the boulder.

What's Happening

Conditions are very similar to 2002, with perhaps somewhat less cover of barnacles. We expected both young Fucus and mussels to colonize the rock by now, as they had in 1994-95, but they have not. This could be due to a lack of reproduction in both species or heavy grazing by animals such as limpets and snails. Neither are apparent.

What You See

In 2005, the boulder has a medium and scattered covering of Fucus plants (rockweed). Barnacle density remains high on the right side of the boulder. Again this year, no mussels are visible. On the left side are a number of greenish brown filamentous algae, some drooping down and covering the medium-sized Fucus plants. On the beach face, along the yellow transect line, the density of Fucus has decreased considerably compared to 2004. In the background, the eelgrass bed (Zostera marina) appears to be less dense than in 2004.

What's Happening?

Conditions in 2005 are very similar to 2004 and perhaps 2000. But no dramatic change is evident. Once again it appears that the young Fucus plants that started growing before or during 2004 have continued to grow but also have gotten thinned out, especially on the beach face, while the green filamentous algae has increased. There appears to be no evidence of recruitment of new Fucus plants in 2005.

What You See

In 2007, the boulder is completely "smothered" by a thick growth of adult rockweed (Fucus) plants, so thick that it's difficult to identify other organisms that may be hiding among the foliage. When we looked closely, we saw lots of tiny (baby) mussels attached to the plants, and when we lifted the plants to see underneath, there were barnacles. Although it is difficult to see, these are large Fucus plants with lots of swollen reproductive blades. A thin band of the filamentous green algae remains along the lower edge of the rock. The beach face below the boulder has about a 50% cover of large Fucus plants and a white covering of barnacles. The eelgrass bed is difficult to see, but it doesn't appear to be very dense.

What's Happening?

Conditions in 2007 are dramatically different than any previous year, since 1991. During that year, the boulder was also "smothered" with young Fucus plants. That was only two years after the oil spill! Now, 16 years later (and 18 years after the spill), we see a very similar situation. It appears that young plants colonized the boulder in 2005 and 2006 and then grew extremely rapidly to a reproductive stage.
Why would this rich growth happen now, especially since we haven't seen anything like this for some 16 years? Perhaps the water temperature has changed to favor the rapid growth. Plants need nutrients, such as nitrogen. Perhaps nitrogen levels in this area in 2006 to 2007 were higher than average over the past 16 years. Or maybe it was a wet spring and the young plants were not exposed to dry conditions during low tides. We will have to explore these ideas.
Will the abundance of life on Mearns Rock ever stop changing? How long should we keep looking at it? What do you think the growth will look like in the summer of 2008, 19 years after the oil spill?

What You See

Once again there is very little rockweed (Fucus seaweed) on the rock except for a few stragglers on the lower left corner of the boulder. Bare rock is visible, occupying about 20% of the surface. The whitish and greenish barnacles dominate the cover on the upper half of the rock. A close-up view of the upper right corner shows three stages of barnacle cover: larger older barnacles stained green with microscopic algae, mid-sized white barnacles and, at the top, a heavy set of small or baby barnacles. Small mussels are scattered in the cracks. By contrast, there remains a heavy cover of rockweed and other seaweeds on the beach face at the bottom of the rock. In the water, there seems to be very little eelgrass.
The absence of the rockweed now allows us to see that the rock surface has about a 50% cover of white barnacles and some black areas. In a close-up view, we see that there are two size classes of barnacles: older, large ones and many tiny new ones. In addition, the black spots and regions are juvenile mussels. Last year, we saw baby mussels under the rockweed. This year, they are exposed and appear to be growing.
It is interesting that, despite the loss of rockweed on the rock, there is still a heavy cover of it and other seaweeds on the beach face. We also see the continued presence of eelgrass in the water behind the rock.

What's Happening?

Not much has changed since 2008 other than possibly a loss of eelgrass in the water behind the rock. The cover of marine life has been fairly poor since 2007: this represents a rather longer period of low biological cover than in past decades (for example, 1991 and 1992, or 2000 and 2001). It seems that rockweed plants have not settled on the rock for several years. Based on cycles during the previous two decades, we might have expected a rich cover of new juvenile rockweed plants and larger mussels, but neither has happened. Perhaps there has been little or no production of rockweed (Fucus) spores during the past several years, and no or poor production of mussels. However, barnacles seem to have "recruited" onto the rock over the past several years with several size or age classes present.
The future? If there is no recruitment of newrockweed or mussels during the next year (2009-2010) the rock may become quite bare, perhaps completely white with barnacles.

For the second time in a row we were unable to visit Mearns Rock in the summer of 2010, but Mr. David Janka, owner and Captain of the Auklet, Cordova, Alaska, was able to visit the site on June 16, 2011.

What You See

Both the rock and the underlying beach face are smothered with algae. Most of the algae is a slimy green matted filamentous alga, possibly Pylaiella spp. There are scattered rockweed (Fucus spp.) plants on both surfaces. What look like dark mussels along the bottom edge of the rock are actually dark brown old Fucus blades. There may be more Fucus plants buried under the filamentous algal mats, or even some mussels and barnacles, but we just can't see through the mats.

What's Happening?

Practically nothing has changed since 2010. The upper right corner of the rock, which was partially bare in 2010 now has some young Fucus plants attached. These were visible in 2010 as very small young plants. This is the first time we've seen persistence of the slimy filamentous algal mats for two years in a row and so that situation is unique. That does not mean that filamentous algae persisted through the winter of 2010-2011 since it is probably an annual.
Lesson at this point? Based on past "performance" and variability, we had expected the filamentous mats of 2010 to disappear in 2011. It didn’t. The year-to-year variability in conspicuous biological cover and species dominance, that we have gotten used to during the past two decades, has stopped, at least temporarily. This in itself—cessation of year-to-year variability—is noteworthy. Just when you think you have cause to understand and anticipate variability (as in our 2010 narrative), it stops.
Are we now in a period of multi-year (two year) stability? What else has not changed much in the past two years? One thing is the climatology. Pacific Ocean climate indices, such as the El Niño Southern Oscillation Index, and the Pacific Decadal Oscillation Index tell us that an unusual back-to-back "La Niña" pattern has persisted since the fall of 2009 (sort of like the parallel, back-to-back, economic downturn!).
We have similar photos of nearly 10 other intertidal locations in Prince William Sound. We need to look at these to see if what has been happening at Mearns Rock for the past 22 years is also happening elsewhere. Stay tuned!