Northwest Dive Club

One of the things I've been very curious about, is what changes we are going to see in other species' abundance, now that one of the most common and aggressive predators in the Sound is all but gone.

I have noticed on my recent dives that I seem to be seeing a LOT more brittle stars, and also a ton of juvenile sea cucumbers. Anybody else noticed anything that seems more common now?

many more Green sea urchins at Keystone Jetty. Pycnopodia not gone yet but mortality still diminishing their numbers.

Mussels and urchins

Another vote here for green urchins- they're popping up in all sorts of places where I've never seen them before.

I've been reporting more green urchins on my REEF surveys certainly.

I asked these questions as well, here are some answers I got from
Ecologist and marine biologists who study these kinda of things and are also very interested to hear how our observations match the keystone species and changes in biodiversity.

the green urchins are related to mottled star. That evasterias is known to eat green urchin recruits. (And barnacles)

Pisaster goes after mussels and barnacles

Pycno goes after whatever it can but seems to LOVE little neck clams and soft stuff like dead bodies of anything (major scavenger of sea floor). I bet a big pycno can out match a baby cucumber speed wise any day. (But I'll test that next time I have a chance.

Brevispinus is known for its clam digging, I got video today of one with tentacles stretched a foot or more down a geoduck hole.

There are more I can list if folks are interested , but don't want to skew your observations

I'm noticing a bunch more opalescent nudibranchs. I see a lot of red gilled nudis and other types that look lile red gilled, but actual opalescents don't seem to be that common.

Nudibranchs probably have their own unrelated boom and bust cycles, but there ya go.

There should be some literature out of the UW in the 60's and 70's about how the inter-tidal environment changes in the absence of sea stars. Bob Paine (cited as R.T Paine) and several of my dad's fellow grad students had several study sites on Waadah Is. in Neah Bay that were monitored while they were purposely kept free of sea stars. It looks like some of the papers show up in Google Scholar .

I've spent a bit of time in Bob's office and home discussing the implications (he was the ecologist I mentioned earlier). We won't see the same as they saw at Tattoosh because we don't have the same critters/critter interactions. The beaches were cleared of pisaster and the california mussels moved in and took over, choking out the biodiversity of the beach. I get the impression he feels ours will be more subtle without the very aggressive mussels like they saw out there. We discussed the question of if the stars were a true 'keystone species' in the mid puget sound ecosystem, and only time will tell. Additionally we have seasons underwater so although we are currently observing this or that, it will take a few years to really be able to "see" the true changes and how things stabilize out.

if you are interested in this stuff, here is a great book...

renoun wrote:There should be some literature out of the UW in the 60's and 70's about how the inter-tidal environment changes in the absence of sea stars. Bob Paine (cited as R.T Paine) and several of my dad's fellow grad students had several study sites on Waadah Is. in Neah Bay that were monitored while they were purposely kept free of sea stars. It looks like some of the papers show up in Google Scholar .

Jan K wrote:many more Green sea urchins at Keystone Jetty. Pycnopodia not gone yet but mortality still diminishing their numbers.

Ditto at Redondo.

I haven't been there in several months, and I was close to marking abundant on the Green Sea Urchins.

There can't be many more urchins this immediately right? How long have sea star populations been reduced and how long does it take a green urchin to reach an adult size? Wouldn't this just be urchins emerging and not increasing in population?

Good to keep measure of these for sure!

We dove the Maury Island barges today, and I was surprised to see a number of large green urchins, both in the boulder field and amidst the barge wreckage. I can't recall having seen them there before.

We saw not one sunflower star. I saw one ochre, and two Stimson's.

The seastar die off began last July per the retroactive reports i've been getting. The green urchins can absolutely grow quite a bit in a year.

The seastars that are missing ate green urchin babies, so it makes sense that we'd get an increase in population with nothing eating the young.

My Dec 2013 footage of Maury Island Barges shows a huge number of "goo remains" from sunflower stars.

Oh, yes . . . we dove there about six months or so ago, and it was tragic.

Yesterday, there were almost no stars at all. I saw a pink, one ochre, a couple of Stimson's, and a blood star. It's hard to remember how colorful our dive sites used to be :(

I was also wondering, yesterday, whether the reduction in zooplankton from removing tons of spawning sea stars from the Sound will affect any of our populations.

Lit I've seen shows fast growing greens reach about an inch test diameter in two years and adult size as fast as 5 years? Sure this isn't a change in detection rather than abundance? Not trying to wrench on a point but do want to hear opinions as it does affect those who survey urchins as part of their job

It could be the urchins are moving in from the neighborhood where we divers did not venture before.
My observation of greater numbers of Greens are from Keystone Jetty. I seldom swim too far from the jetty...

I have an email out to Bob Sizemore, one of the scientists doing the urchin surveys in the Sea otters vs. climate change video last year. He has been studying Sea Urchins for 25 + years, so may have some insight. Will forward on his reply when I get it.