Aquatic Erratics as Refugia

I've spent the past few days going through data, photos and videos from our 2008 dive surveys at Elwha in preparation for a planned USGS report. I've been struck by the role that relief - in the form of reef or boulders - seems to play in enhancing diversity and supporting life. The example shown here is from an area to the east of the river mouth - a region characterized by fairly expansive plains of mixed sediment (shown in the photos) and decreased densities of large invertebrates and algae. Boulders are also rare to the east of the river mouth, but where they do occur they seem to act as islands for the variety of organisms that are somehow reliant on the hard surface, stability or shelter they provide.

The video is a stark example of this. We came across a large boulder in the middle of this plain of mixed small sediment, which was encrusted with kelps and invertebrates (including the giant barnacle, Balanus nubilis). A little cave under the boulder seemed a perfect shelter for a Giant Pacific Octopus, and sure enough there was one in there. The video is poor, but you can make out the mantle and siphon of this mid-size octopus.

"I was gobsmacked!"

So this is a pretty cool story in and of itself for those of the coast nerd variety. What really caught my eye, though was the absolutely wonderful use of the phrase, "I was gobsmacked" by Aussie research biologist Julian Finn. Finn was talking of observing an octopus collecting and transporting coconut shells for later use as shelter. Doesn't seem like much to get too gobsmacked about until you recall that Octopi are molluscs. This only adds to the reputation of octopi as being the smartest invertebrate in the class. They probably have to hide in coconut shells only because they are routinely bullied by the dumber invertebrates in the ocean.

Anyhow, I am presenting tomorrow at a conference in San Francisco, and will definitely be thinking hard today on how to work the phrase, "I was gobsmacked!" into my talk. I love it.