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.
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.