The Echinoblog

Video & Images from the Census of Marine Life Big Wrap Up!

2009-11-24T11:35:00.000-08:00

So, the big Census of Marine Life is racing towards its final year in 2010 and a big end-of the year press release has hit the media, including the video below!

If ya' skip over all of the jellies and other non-echinoderm (but still pretty cool) animals, towards the end is a GREAT video of the swimming sea cucumber Enypniastes from the Gulf of Mexico!! (shown above):

There's been a flurry of "best of" type photos, including this cool shot of a bunch of brisingids (Novodinia spp.) and a goniasterid (looks like Evoplosoma) perched on a bunch of deep-sea corals in and around New Zealand (>1000 m based on the original captions).
Its a light Echinoblog week but here in the US, its Thanksgiving week, and everything is just a little bit slower! Especially with everything getting colder and darker!

There will continue to be sporadic, light posts this week..with next week back to "normal"...

Enjoy!

Echinoblog Holiday Life Lesson # 34

2009-11-23T13:02:00.000-08:00

Do NOT mix up your holiday shortbread with cookie-shaped starfish!! (Ceramaster granularis)

(no actual starfish specimens were harmed in the production of this blog)

The Pisaster Post! Posterchild or Portent ??

2009-11-17T00:25:00.000-08:00

(from MarineBio.net!)

This week, we're talking about the Pacific Northwest Intertidal!!

And what animal is more iconic to this area then Pisaster ochraceus (family Asteriidae)-the familiar intertidal Ochre Star found on rocky, mussel-laden substrates on from Alaska to California to Mexico. Some more basic information is here.
Interest on this species has shifted over the years and seems to change based on some of the "big science" of the day. Yet another sign of how the humble starfish has incorporated itself into the fabric of the BIG scientific picture!

So, today some highlights of the importance of the ever-humble intertidal Pisaster ochraceus and how its study has varied over the years....

1. The Keystone Species Concept-Ecology's Posterchild. Probably one of the most lasting ideas from the 1960s and 1970s was the hypothesis developed by ecologist Robert T. Paine who identified Pisaster ochraceus as a keystone species (keystone shown below in grey).
To quote Wikipedia:

A keystone species is a species that plays a critical role in maintaining the structure of an ecological community and whose impact on the community is greater than would be expected based on its relative abundance or total biomass

This keystone is a crucial block in an arch that keeps it from collapsing. This is analogous for Pisaster's influence on the mussels and the other invertebrates that exist in a rocky intertidal ecosystem.
The loss of the "keystone species" results in a drastic shift among these species....The idea has endured and while not embraced by everyone- remains a mainstay in basic ecology books. More details on this notion can be found here.

Pisaster along with its prey, the mussel Mytilus are almost ALWAYS the featured example... the POSTER child for the keysone concept-and for this reason, is probably even better known then the Atlantic Asterias!
This was (and continues to be) an important ecological notion during a time when the ecosystem and ecologists were in ascendance and ecology was a huge primary mainstay of biological research!

Time passes.

How has Pisaster changed to suit the most recent research paradigm??

2. Pisaster as a Portent of Change?? The Canary in the Cage of Climate Change??
Probably one of the biggest, new research directions these days?

Understanding Climate Change and in turn...increased ocean temperature, which has a HUGE impact!

It affects ocean water chemistry. Water chemistry in turn can change everything from mineral absorption, feeding behavior, physiological systems to larval settlement. These in turn can have influence on MILLIONS of tiny larvae in the water. As well as the MANY adults those starfish grow into.

This translates into many people interested in the effects of increased temperature and heat relative to the ability of common species to adjust. Will Pisaster ochraceus take on a new status as a possible indicator species (i.e., canary in a coal mine) for climate change effects in marine systems?

Here is a survey of three recent studies (2008-2009) that have looked at how Pisaster holds up!

Elevated water temperature and carbon dioxide concentration increase P. ochraceus growth!

(Diagrammatic graph by Echinoblog Art Department!)

Rebecca Gooding, Christopher Harley and Emily Tang at the University of British Columbia published this study in the Proceedings of the National Academy of Sciences wherein they found that increases in temperature from 5 to 21 degrees C led to increases in feeding AND overall growth.

This bucked the predictions that the decreased carbon dioxide resulting from increased temperature would prevent animals that use calcium carbonate to form their skeletons (such as coral)!!

Solar radiation plays a role in P. ochraceus habitat selection

(Diagrammatic graph by Echinoblog Art Department!)

A 2008 paper by Jennifer Burnaford and Melissa Vasquez at the University of Puget Sound studied where P. ochraceus occupied habitat and their tolerance of Ultraviolet radiation.
The short version of this-the authors found that in artificial lab experimetns, P. ochraceus avoided ultraviolet and "photosynethetically active radiation" and observations of Pisaster in the intertidal found that 85% of them occurred in shaded habitat underwater where they were shown to preferentially avoid direct exposure to sunlight (see diagrammatic graph above!).

P. ochraceus avoids extreme body temperature by pumping its body full with cold sea water!!

(Diagrammatic graph by Echinoblog Art Department!)

Sylvain Pincebourde, Eric Sanford, and Brian Helmuth recently published this paper (2009). A popular account can be found here (and for shame to Live Science for misspelling "ocher").

Their paper details how Pisaster ochraceus was observed to increase the amount of colder water in their body cavity lowering their body temperature during the subsequent low tide in response to the temperature.

Sense it getting warm? don't like it? Just PUMP IT UP! with cold water! (see diagram above)

But climate change has a huge potential impact on animals that do this...to quote in their words:

When placed in a global change context, these results suggest that a continued increase in ocean temperature may compromise the ability of sea stars to avoid thermal stress during aerial exposure at low tide.

Has the humble Pisaster ochraceus gone from ecological poster child to a possible portent of climate change to come??? Time will tell....

Meet...The Farallons: ROCKY Intertidal Wilderness of San Francisco!!!!

2009-11-16T17:15:00.000-08:00

So, one of my esteemed colleagues at the California Academy of Sciences-Dr. Rebecca Johnson Rodgers, who has worked with the Echinoblog while teaching at San Francisco State,is currently out on the Farallon Islands with the Rocky Shore Partnership monitoring various intertidal invertebrate critters. So, I wanted to give them some bloggy love:
Click here for their blog...
For those who are not familiar, the Farallon Islands are some remote islands, about 27 miles outside the Golden Gate Bridge (outside of San Francisco Bay).. Here is the Wikipedia page for the Farallons for more..

But the short version is, that they are remote islands that are protected as a wildlife refuge. The Farallons are great for birdwatching and have lots of great (hopefully still...) pristine intertidal reef habitat.

Plus, as a bunch of rocky islands out on the outskirts of San Francisco Bay, you get lots of this...

Along with many of the classic California invertebrate fauna..

Leptasterias "hexactis", shown here with brooding eggs!! This is part of the Leptasterias species complex which I have written about here and here
and, of course, the good ol' workhorse starfish Pisaster ochraceus, which I will be writing up in the blog later THIS WEEK!!!

and just because they're so dang beautiful...these mollusks too!!! This used to be called Tonicella lineata, but I think the name's been changed recently...
....and back in the Paleozoic when I took Intertidal Ecology, this thing was called Calliostoma, but I gots no idea what the kids are calling it these days!
GO check out the Rocky Shore Partnership BLOG and I'll be back in a few days with some PISASTEROUS starfishy goodness for all o' y'all!

Tosia Times TWO! Discovering NEW CRYPTIC species of Australian Biscuit Stars!

2009-11-09T15:34:00.000-08:00