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Mearns Rock: Watching Ecological Recovery from an Oil Spill

Intertidal boulder with moderate cover of Fucus (rockweed) and a filamentous algae.
Intertidal boulder with heavy cover of Fucus (rockweed).
Intertidal boulder with a more vigorous cover of Fucus (rockweed) and mussels.
Intertidal boulder with a scant cover of Fucus (rockweed) and barnacles.
Intertidal boulder with brown seaweed, bare rock, and patches of barnacles.
Intertidal boulder half covered by Fucus and 20% covered by barnacles and algae.
Intertidal boulder covered 80-90% with seaweeds.
Boulder and beach with heavy mats of filamentous seaweed and some algae.
Boulder and beach nearly fully enveloped by heavy mats of filamentous seaweed.
Boulder with some Fucus (rockweed) plants.
Boulder with some Fucus (rockweed) plants.
Boulder completely covered by a thick growth of adult Fucus (brown seaweed).
Boulder with moderate to heavy cover of young rockweed except in center.
Boulder with heavy covering of young rockweed and barnacles.
Boulder covered in young algae and thick with barnacles but no mussels.
Boulder with some Fucus algae and sea lettuce.
Boulder dominated by barnacles.
Boulder covered by several kinds of algae, barnacles, and small mussels.
A heavy cover of a grayish, slimy seaweed has joined the algae on the boulder.
The boulder's second crop of Fucus algae nearly covers it.
A brown seaweed and a filamentous algae cover the boulder
A boulder almost covered with the seaweed Fucus.
Boulder with algae and young barnacles.
Fucus is making a comeback on the boulder.
Boulder dominated by mussels and no algae.
Algae covers about 20% of the boulder's surface.
A boulder about 50% covered with larger, older seaweed.
An entire boulder is covered with gold-brown algae.
Boulder partially submerged in water and covered in algae.
Intertidal boulder with moderate cover of Fucus (rockweed) and a filamentous algae.
Mearns Rock 2018

During an early morning low tide on Thursday, August 8, 2018, Mr. David Janka of Auklet Charter Services again visited Mearns Rock, sending his photos from the field to Seattle two hours later. This represents the 29th consecutive year of annual photos of the rock site.

What You See

The rock and its beach face are covered with two species of seaweeds, the golden-brown rockweed, Fucus sp, and dark green mats of a filamentous algae. The patches of rockweed cover 35%-40% of the rock surface. There are several small bare spots, exposing patches of small white barnacles.

Along the top, upper right, and half way down on the right, are patches of black medium-sized mussels, covering approximately 5% of the surface.

Mr. Janka also took a closeup photo of the upper right side, and to our surprise, it revealed an ocher sea star, Pisaster.

What's Happening

Conspicuous marine life on the rock has changed dramatically from what it was one year earlier, in August 2017. The cover and thickness of rockweed has declined by half, and the cover of mussels has greatly decreased to one-tenth of the cover seen a year earlier.

 Close view of a boulder with various marine life species growing on it.
In the lower right portion of this image, a sea star, Pisaster, is visible. (David Janka) Click image for larger view.

Of great interest is the appearance of sea star, Pisaster, seen in the inset at right. This is the first time in nearly three decades of observation that we have seen a sea star on the rock. Mussels are preferred food items of this and other species of sea stars. In addition, recall that in 2014, sea stars along the entire west coast and parts of Alaska were killed by a Sea Star Wasting Disease, caused by a widespread virus. Sea stars have been recovering along the coast, so Mr. Janka's image is good to see, even if they are voracious predators of mussels!

We again thank Mr. Janka for visiting the site and sending his great photos.
 
 
 
 

Credit: David Janka
Intertidal boulder with heavy cover of Fucus (rockweed).
Mearns Rock 2017

Mr. David Janka, Skipper, Auklet Charter Services, once again visited Mearns rock at low tide on August 6, 2017.

What You See

There is a nearly 100% cover of rockweed (Fucus) on the upper two-thirds of the rock, about 60% overall. There is also about 80% percent cover of rockweed on the cobble beachface at the base of the rock. There is a thin layer of a filamentous seaweed on the lower third of the rock, and on the right are patches of black mussels and scattered white barnacles. Behind the rock we see eelgrass (Zostera marina) in the water.

What's Happening

It has been 28 years since we started photographing this site, and the cover of seaweeds, mussels and barnacles has undergone several periods of “boom and bust”. The cover of Rockweed has more than doubled since 2016, and there is much less bare rock since then. We are surprised that the cover of mussels we saw in 2016 has not decreased much in 2017.

The rockweed plants are turgid with reproductive floats, or receptacles, so they may be shedding reproductive products into the water during high tides. Based on past years, we would expect the adult rockweed plants to “senesce” (age) and disappear by next year, perhaps leaving space for new ‘recruits’ (baby rockweed plants). We might also expect the mussels to disappear, perhaps consumed by shore birds or sea otters. Only time will tell! Tune in again next year.

We thank Mr. Janka for visiting the site again and sending his great photos.

Credit: David Janka
Intertidal boulder with a more vigorous cover of Fucus (rockweed) and mussels.
Mearns Rock 2016
What You See

In this August 1, 2016 photo, the rock and beachface have about a 25% cover of small and medium sized Rockweed (Fucus spp.) and widely scattered barnacles (white spots in the photo). But also moderate-sized patches of Mussels (black areas). On the lower-left corner of the rock is a patch of a different brownish seaweed. Note also the areas of dense eelgrass in the water (behind the rock).

What's Happening

The most surprising thing in summer 2016 is the return of mussels! It has been over two decades since mussels were a conspicuous part of the marine life here (see the 1993 to 1995 photos). There were many baby mussels on the seaweed in 2007, but they did not survive to visible adults in 2008. In 2015 they may have settled as practically-invisible specks, but were certainly not apparent in that photo. During the summer, we heard from other researchers that 2016 was a "big year" for inter-tidal mussels in Prince William Sound and beyond. The cover of Rockweed has increased a little since 2015, but is still way below the cover seen in 2012 and 2013. These observation raise the question: What will the scene be like in summer 2017? Will the mussels and Rockweed continue to grow and expand? Indeed, why did it take several decades for mussels to conspicously re-assert themselves? Do we have to wait two more decades to see mussels here again?

Credit: David Janka
Intertidal boulder with a scant cover of Fucus (rockweed) and barnacles.
Mearns Rock 2015
What You See

This year's photo was taken during a low tide on Saturday, August 2. The cover of the seaweed Fucus (rockweed) on the rock remained extremely low in 2015. There are few young plants and a lot of small white barnacles. A low density of young Fucus plants is visible on the top of the rock. Closeup photos revealed a light cover of small mussels. The predominant cover is barnacles, which increased since 2014.

What's Happening

There may be new "recruitment" of young Fucus plants in recent weeks. The last time we saw a good recruitment (cover of young plants) of Fucus was around 2006, with a peak in overall cover around 2010. 2015 represents the fourth time in a quarter century that the seaweed cover has nearly disappeared. While we don't know why these multi-year "ups and downs" happen, we do know some things that could contribute. One is seaweed senescence ("aging"): individual Fucus plants live about 4-5 years. Another is loss by "grazing" (and, for barnacles, by predation). Finally, another factor may be year-to-year climate variability that can increase or decrease temperature, nutrients, and/or disperse or concentrate eggs and larvae. On this last point, measures of our changing ocean conditions include the Pacific Decadal Oscillation (PDO) and the El Niño/La Niña cycles. Look back through records of these (data are online); our coast has experienced cooling conditions since 2007. However, everything began changing in 2014, with the PDO indicating warming waters, a warm "blob" of water off the West Coast of North America, and on top of that, an El Niño now well-developed in the Pacific. The high cover of Fucus plants on the rock in the summer of 1997 accompanied a major El Niño event, so maybe we will soon see a major regrowth. Maybe!

Credit: David Janka, Owner and Skipper of Auklet Charters, Cordova, Alaska
Intertidal boulder with brown seaweed, bare rock, and patches of barnacles.
Mearns Rock 2014
What You See

The cover of the seaweed Fucus (rockweed) on the rock continued to decline between 2013 and 2014. There are few young plants and a lot of bare rock with scattered patches of small white barnacles. Small black patches among barnacles appear to be young mussels. There is a higher cover of Fucus on the beach face, at the base of the rock, than on the rock.

What's Happening

There appears to have been no new "recruitment" of young Fucus plants in the past year. There may be new barnacles and especially mussels. The last time we saw a good recruitment (cover of young plants) of Fucus was around 2006, with a peak in overall cover around 2010. Since 2007 the North Pacific Ocean has been in a "cold phase." However, during the spring months of 2014, conditions have begun to shift into a "warm phase." As of June 2014, we see no dramatic change in what's on the rock, except possibly the occurrence of new mussels. If the warm phase continues into the fall and winter of 2014–15, we may see some dramatic changes. Dr. Rob Campbell, biological oceanographer with Prince William Sound Science Center in Cordova, Alaska, volunteered to take the photo of Mearns Rock on June 25, 2014, during his monthly oceanographic survey of Prince William Sound.

Credit: Rob Campbell, Prince William Sound Science Center
Intertidal boulder half covered by Fucus and 20% covered by barnacles and algae.
Mearns Rock 2013
What You See

The rock has about a 50% cover of the seaweed Fucus (rockweed) and 10% cover each of a dark filamentous seaweed and of white colonies of barnacles. There may be more barnacles hidden under the seaweeds. Mussels are not apparent on close inspection. About half of the Fucus seaweed is nearly black and appears dead. However, on the upper left corner fresh “sprouts” of Fucus blades are beginning to appear.

What's Happening

Clearly, a lot of Fucus has disappeared since last year. Note that the Fucus appears to have “changed places.” Well, not exactly. The area on the upper left side of the rock had very low vegetative cover in 2012 but more in 2013. By contrast, where the Fucus cover was heavy in 2012, it is now virtually gone. What is somewhat interesting is that there appears to be recently killed or dead seaweed still stuck on the middle portion of the rock next to small patches of new growth. It’s not clear we’ve seen it like this before (but please check photos from previous years to see if you agree). This photograph was taken in mid-August, six weeks after a rare heat wave in late June that parched much of south-central Alaska. NOAA scientists Mandy Lindeberg, who visited other sites nearby in late June said that she observed dead, dying, gaping, and smelly mussels and “burned” Fucus at the higher intertidal elevations. It would be interesting to compare the actual intertidal water and air temperatures at this time. But, as always, this may or may not be the cause of the reduced seaweed cover: it may have started declining naturally. So what do you think will happen by next summer, 2014?

Credit: Dan Crowther, Prince William Sound Science Center
Intertidal boulder covered 80-90% with seaweeds.
Mearns Rock 2012
What You See

The rock and beach face are about 80 to 90% covered with large mature Fucus seaweed (rockweed) and a small amount of filamentous and leafy green seaweeds. The Fucus looks stressed from dehydration. However, across the middle of the rock we can see plants with enlarged reproductive floats, suggesting those plants are or have produced spores. If mussels and barnacles are present, they are not visible due to the moderately heavy seaweed cover.

What's Happening

Let's go back to 2007. This rock was covered with Fucus at a density similar to this year. Then in 2008 it disappeared from this boulder (but not the beach face), revealing a high density of barnacles. Small Fucus plants appeared in 2009. In 2010 and 2011, they grew but were also covered by a slimy filamentous algae, possibly Pilayella littoralis, which, according to the reference book Seaweeds of Alaska, "commonly grows on Rockweed and blooms into large mats, covering its host." Then, in the summer of 2012, the filamentous algae have virtually disappeared, or died, revealing what appears to be a moderately heavy cover of large but aging Fucus plants. So, the rock has experienced a six year cycle of "boom-to-bust-to-boom" seaweed cover. This represents the third time in the past 24 years that we have seen this complete cycle of vegetative cover on this particular boulder. In short, it looks like seaweed life in this intertidal area undergoes 100% change over periods of five to seven years. If true, what would you expect we will see next year, 25 years into our observations?

Credit: NOAA
Boulder and beach with heavy mats of filamentous seaweed and some algae.
Mearns Rock 2011

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!

Credit: David Janka
Boulder and beach nearly fully enveloped by heavy mats of filamentous seaweed.
Mearns Rock 2010

We were unable to visit Mearns Rock in the summer of 2010, but Ms. Mandy Lindeberg, from NOAA's Alaska Fisheries Science Center in Auke Bay, Alaska, was able to visit the site in June. She took some extraordinary photos.

What You See

Not what we expected, that's for sure! Except for the extreme upper right corner of the rock, the rock and the beach face are nearly fully enveloped by heavy mats of one or more species of filamentous seaweeds. The rockweed (Fucus) plants that persisted on the left side of the rock in 2008 and 2009 are still there and their blades look plump with spores. We can't tell much about the cover of mussels and barnacles, except on the upper right corner, which is practically encased in barnacles.

What's Happening?

The "main event" of 2010 appears to be a large-scale recruitment and growth of filamentous seaweed, basically smothering the entire mid and low intertidal zone. The last time we saw such a heavy growth of filamentous seaweed was a decade ago, 2000 (and prior to that, 1998). Unlike the perennial seaweed Fucus, which reaches ages of four to five years, these filamentous seaweeds are annual: they can come and disappear in a relative "flash." Because of this cover, there's not much else we can say about what is happening with the old "standbys": Fucus, the mussels, and barnacles. It is possible that, even if 2010 had a good year of production, these species might be excluded from settling on the rock (and the beach) because of the filamentous algal growth.

This leaves us really wondering what 2011 will be like. Following the heavy filamentous seaweed cover of 2000 there was resurgence of rockweed cover on the rock in 2001, but it nearly disappeared in 2003 and there was no "recovery" of it until 2004, leading to heavy adult rockweed cover through 2007.

Lesson at this point? The more we monitor and observe the less we seem to be able to anticipate what is will happen next. Without additional information, all we know is that there is extreme variability of the conspicuous intertidal marine life on these shores. That is, there is a natural range of species abundance that is close to 100%. We know that change is the rule, not the exception. We know there is no "stable state" for these marine organisms, on these shores.

In the fisheries world, in the North Pacific, there is similar "inter-annual" variation in the abundance and composition of fish and shellfish, and attributes of these "cycles" are related to major climate-change events such as the El Niño (warm)/La Niña (cold) periods and to the Pacific Decadal Oscillation. Perhaps we should be seeing if this intertidal marine life is also responding to those events.

Credit: NOAA
Boulder with some Fucus (rockweed) plants.
Mearns Rock 2009
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.

Credit: NOAA
Boulder with some Fucus (rockweed) plants.
Mearns Rock 2008
What You See

In 2008, there is very little rockweed (Fucus) on the rock. Almost all of the large reproductive plants seen in 2007 are now gone, except for a few stragglers on the lower left corner of the boulder. 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 Fucus. 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?

The thick cover of reproducing Fucus seen in 2007 has either died out or possibly has been removed by grazing animals or even ice scouring in the winter of 2007-2008. Since we don't visit the site in the winter, we don't know if ice was present. However, the changes are reminiscent of what happened between 1991 and 1992 or between 2000 and 2001. The presence of very tiny white barnacles suggests that they recruited onto the rock very recently and perhaps after the Fucus disappeared. Likewise, it appears that the baby mussels that settled under the Fucus in 2007 are now growing. Will their future be like what happened between 1992 and 1993, when Fucus disappeared and there were a lot of mussels that continued to grow into 1994 and then disappeared? Maybe predators, such as seastars and predatory snails, will come onto the rock and eat the new mussels before they have a chance to grow! It's tough to predict what's going to happen next.

Credit: NOAA
Boulder completely covered by a thick growth of adult Fucus (brown seaweed).
Mearns Rock 2007
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?

Credit: NOAA
Boulder with moderate to heavy cover of young rockweed except in center.
Mearns Rock 2006
What You See

In 2006, the boulder has a moderate to heavy cover of young Fucus plants (rockweed) except in the central "saddle" area. The filamentous green algae is present only along the lower margin of the rock. The white area in the central "saddle" portion of the rock is due to a set of barnacles. Also note the very white heavy set of barnacles on the stones along the beach face. Eelgrass remains present in the water just beyond the rock.

What's Happening?

Conditions in 2006 are quite changed from 2005. The medium sized Fucus seen in 2005, especially in the central "saddle" area of the rock, have disappeared and only a few very young Fucus plants are visible here. It appears there was a die off of the 2004-2005 Fucus plants but they were not replaced in exactly the same areas by the "new" 2006 plants. And new barnacles quickly colonized bare rock areas.

Credit: NOAA
Boulder with heavy covering of young rockweed and barnacles.
Mearns Rock 2005
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.

Credit: NOAA
Boulder covered in young algae and thick with barnacles but no mussels.
Mearns Rock 2004
What You See

In 2004, the boulder has a heavy covering of young (greenish-brown) Fucus plants (rockweed). Barnacle density remains high on the right side of the boulder. Again this year, no mussels are visible. In the lower left corner of the boulder, the patch of sea lettuce seems to be dying back. On the beach face, the density of Fucus is similar to that on the boulder. In the background, an eelgrass bed (Zostera marina) is visible in the water.

What's Happening

Conditions in 2004 are very similar to 1996. At that time, we wrote that it appeared that a second "wave" of recovery was occurring. Now it looks like a third wave of regrowth is occurring. During the first years of recovery, there was a heavy growth of mussels; however, that doesn't appear to be the case for the second and third waves of regrowth.

We had originally thought that there was a five to six year period from new growth to die-off. If that was true, we should have seen a new recruitment of Fucus by 2001. Obviously, the new growth didn't happen for about eight years (until 2003-2004). Thus, the time between significant recruitment events is many years but also variable.

Questions: What do you think this Snug Harbor site will look like in June 2005 and why? Do you think the mussels will ever return?

Credit: NOAA
Boulder with some Fucus algae and sea lettuce.
Mearns Rock 2003
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.

Credit: NOAA
Boulder dominated by barnacles.
Mearns Rock 2002
What You See

In 2002, the boulder is dominated by barnacles, creating a 50% cover. A few large, old Fucus plants (rockweed) on the upper section of the rock make up a 10%–15% cover. None of the green algae that was present along the mid section of the rock in 2001 is present this year. A small amount of green "sea lettuce" (Ulva)—much less than in 2001—is visible in the lower left section of the boulder. In 1993–94, when the rock last appeared quite bare, many mussels covered the boulder; however, none are present now. Overall, the boulder location is a somewhat desolate landscape this year, with more bare rocks exposed than in previous years.

What's Happening

The die-off we anticipated in 2001 is now occurring in 2002. Like in 1994–95, there is an absence of juvenile Fucus plants, but unlike 1994–95, the mussels are not returning. Perhaps they will in 2003?

Credit: NOAA
Boulder covered by several kinds of algae, barnacles, and small mussels.
Mearns Rock 2001
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?

Credit: NOAA
A heavy cover of a grayish, slimy seaweed has joined the algae on the boulder.
Mearns Rock 2000
What You See

Mature Fucus (rockweed) now covers about 10% of the boulder's surface. In addition, there is a heavy cover of a grayish, slimy seaweed (this could be any of three or four seaweed species that can look like this). As in other years, these plants may be hiding barnacles, mussels, or young Fucus plants from our view. The white areas on the beach face look to be large barnacle sets. Eelgrass is barely visible in the water.

What's Happening

As in the 1993 photo, the mature Fucus plants are again dying back. However, at this time, there is no sign of a third new crop of young Fucus.

Credit: NOAA
The boulder's second crop of Fucus algae nearly covers it.
Mearns Rock 1999
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.

Credit: NOAA
A brown seaweed and a filamentous algae cover the boulder
Mearns Rock 1998
What You See

The boulder is now covered with patches of adult Fucus (rockweed) and a filamentous algae, which we think is Pilayella littoralis. We can't see what quantity of mussels and barnacles are present because they are covered by the Pilayella. What other year does this scene remind you of?

What's Happening

Young plants that took hold in 1995 are now maturing.

Credit: NOAA
A boulder almost covered with the seaweed Fucus.
Mearns Rock 1997
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.)

Credit: NOAA
Boulder with algae and young barnacles.
Mearns Rock 1996
What You See

This year, the boulder looks somewhat like it did in 1990. Young Fucus (rockweed) plants cover much of the boulder, young barnacles appear in the open spaces, and the mussels have disappeared.

What's Happening

A second "wave" of recovery has clearly taken hold.

Credit: NOAA
Fucus is making a comeback on the boulder.
Mearns Rock 1995
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.

Credit: NOAA
Boulder dominated by mussels and no algae.
Mearns Rock 1994
What You See

The seaweed Fucus has completely left the boulder, leaving it dominated by approximately 2-year-old mussels (black areas on the boulder) and scattered barnacles. Very little seaweed is growing on the beach face. Where did the plants go? Why aren't they growing here anymore?

What's Happening

In 1993 and 1994, something happened that caused a great reduction in the abundant marine life on this shoreline. NOAA biologists believe that the loss of seaweed, mussels, and barnacles is part of the growth cycle of the marine life, rather than due to oiling per se.

Credit: NOAA
Algae covers about 20% of the boulder's surface.
Mearns Rock 1993
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?

Credit: NOAA
A boulder about 50% covered with larger, older seaweed.
Mearns Rock 1992
What You See

The boulder is now about 50% covered with larger, older seaweed (mainly Fucus). Barnacles are filling in spaces left by dying seaweed. The beach face is heavily covered with seaweed.

What's Happening

The Fucus that was young in the 1990 photo has aged and is now dying off. Why is it dying off?

Credit: NOAA
An entire boulder is covered with gold-brown algae.
Mearns Rock 1991
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.

Credit: NOAA
Boulder partially submerged in water and covered in algae.
Mearns Rock 1990
What You See

In this photograph, taken 15 months after the Exxon Valdez oil spill, you see only the top portion of the boulder because the tide was in at the time that the photo was taken. The boulder's surface is almost entirely covered by young plants of the seaweed Fucus distichus (commonly called "rockweed" or "popweed"), which is abundant on the shorelines of Prince William Sound. On the right section of the boulder (the area of white color) is a settlement of young barnacles. The dark patch (on the right section) is a colony of small mussels.

What's Happening

No oil appears on the boulder because biological processes have cleared it away. NOAA biologists assume that adult Fucus plants that were present at the time of the spill were damaged by the oil and/or the particularly cold temperatures of the previous winter. Young Fucus have grown since that time.

Credit: NOAA
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