Northwest Dive Club

When you dive at a site for a number of years you begin to notice subtle changes over the years. Titlow is one of my favorite sites due in large part to the dramatic pilings covered in Plumose Anemones.

One thing that has been very noticeable this year is the disappearance of the large clusters of Giant Acorn Barnacles and other encrusting animals. The Anemones remain, but otherwise the pilings have become rather bare.

Here's a photo from October 2013. The dark mass at the top of the pilings is made up of barnacles.


Here's a photo from February 2014, exactly two years ago. The barnacles can be seen in the upper half of the picture, especially on the upper left piling




In 2013 the bottom of the piling was covered with large sunflower stars cruising through piles of various shells that fell from above.


I was diving at Titlow on Monday and what really struck me was how bare the upper pilings are. These photos are from the upper area of the pilings. Nothing there at all.




Has anyone else seen this? It doesn't seem to be a seasonal variation, it might be some kind of long term change to the local environment. If so, that's quite a loss to the biodiversity of this area.

Dan

Wow.... Stunning. Rising ocean Temps? That really sux. It seems we are seeing several changes in our waters. Disheartening.

Perhaps we are seeing beginnings of a monoculture from lack of sea stars? Sea stars are messy eaters and its quite likely that they 'fed' the barnacles when they were enveloping their food with their stomach (a lack of lips makes it hard to keep food in their mouth??) Other things that benefit from sea star messy eating are the fish eating type anemones, baby fish, bigger fish, other sea stars, etc...

I have been documenting the exact same phenomenon at our transects off Alki. The piling transects have become remarkably barren.

WOW , that is a huge difference from when i dove there back in 2006 -2009 with bassman and cardiver for thursday night south end dives ... barnacles that Size are Old , very old ...

I noticed this down in the south sound lately as well. A site where last year we consistently harvested muscles and was largely encrusted with barnacles is now almost barren.

I wasn't sure if it was a seasonal thing or not, but it sounds like maybe not.

this is fantastic reporting folks... please keep up with the observations! I will pass this thread on to the Sciency types that have been monitoring SSWS.

I was surprised at the absence of barnacles on the pilings at Wells Point last November.
I also saw very few crab, Cabezon and Ratfish that had been in abundance years before.
Similar at Haines Warf although I only saw a few outer pilings. Seems like a lot more Kelp crab though.
Photos available.

ohopdiver wrote:I was surprised at the absence of barnacles on the pilings at Wells Point last November.
I also saw very few crab, Cabezon and Ratfish that had been in abundance years before.
Similar at Haines Warf although I only saw a few outer pilings. Seems like a lot more Kelp crab though.
Photos available.

+1 on the over abundance of kelp crab. Seems like they are everywhere now.

Potential harbinger of additional acidification. Taylor shellfish is already having a tough time getting oysters to put on shells.

A couple of many articles
http://www.washington.edu/news/2015/03/ ... rbor-labs/

http://www.skepticalscience.com/Puget-S ... -List.html

http://www.pmel.noaa.gov/co2/story/Acid ... +Shellfish

ljjames wrote:this is fantastic reporting folks... please keep up with the observations! I will pass this thread on to the Sciency types that have been monitoring SSWS.

thanks!

I've been diving around here since 2004 and have noticed gradual reductions in the diversity at our most popular dive sites. That change seems most striking in the last two years. Digging around my photos from 2014 at sites that I've frequented bears strong proof of this, none more dramatic than those towering pilings at Titlow. I don't think its attributable to seasonal variation anymore.

Dan

It looks like not just empty barnacle shells, but the animal and the shell are gone! Would acidic changes cause the shell to dislodge or flake apart? I can't imagine them being harvested

Echo wrote:It looks like not just empty barnacle shells, but the animal and the shell are gone! Would acidic changes cause the shell to dislodge or flake apart? I can't imagine them being harvested

https://web.archive.org/web/20080625100 ... e04095.pdf
I found this article which states, among other things, biogenic calcium carbonate can dissolve with increased ocean acidification. So yes, it is possible that the shells could disappear. Acidification also makes it more difficult for organisms to form shells. You could be seeing the first signs of this.
-Curt

In the winter of 2015 the sand underneath the pilings was covered in mounds of barnacle shells. I know that barnacles molt, but it's pretty clear now that those creatures haven't returned.

Hi Dan
Thanks for bringing this up. Nice photos!

I saw a slab of barnacles had fallen off at keystone. It could have just been erosion or a careless diver. But will keep an eye out.