A family trip to the seashore revealed to us yet another instance of the natural world unraveling before our eyes.
We had been on the lookout for Sea Star Wasting Disease this spring. Just two weeks ago, my daughter and I were looking at the purple sea stars around Boulevard Park and Taylor Dock - they all looked good.
Today, my wife and I took our junior scientist out to Larrabee State Park to check out the epic low tide, usually the best time to see the critters of the intertidal. This is what we saw.
Sea stars are the iconic form of sea life at Larrabee. Kids of all ages come to see them. Today, many were dead or dying.
In addition to the stricken sea stars, we agreed that the population appeared to be substantially lower than we had seen at previous very low tides. Previously, it was normal to see clusters of a dozen of more sea stars in any given crevice in the mid to lower intertidal.
At the end stage, the sea star sometimes falls completely apart, the legs literally tearing themselves off the star.
It was a somber trip home. In any trip to a natural place, I try to show my daughter something about the world around us, the systems which are at the same time wondrous and fragile, and how we need to protect them. Today felt like a whole lot more education than I had planned on or hoped for.
According to a site on the disease maintained by University of California Santa Cruz:
As yet the cause of the syndrome is unidentified, and it’s not clear whether it’s a due to an environmental change, disease or something else. Similar die-offs have occurred before in the 1970s, 80s, and the 90s, but never before at this magnitude and over such a wide geographic area.
The currently recorded extent is basically the entire US west coast, from southern California to Alaska.
[Image from
University of California Santa Cruz]
The causes are unidentified, yet the site also notes.
Two common attributes for many of the sites are: (1) the period prior to wasting was characterized by warm water temperatures, and (2) the effects are dramatic.
The implications are clear:
Ecologists consider both sunflower and ochre stars to be keystone species because they have a disproportionately large influence on other species in their ecosystem. In fact Pisaster ochraceus was the basis of the Keystone species concept because of its potential to dramatically alter the rocky intertidal community in which it occurs.
So, the species of sea star that we saw dying today (Pisaster ochraceus) is not only a Keystone species, it is the type example of such a species.
If this sounds familiar, it is. Same story, different species.
In the past few years, populations of some species of bats have been devastated by
White Nose Syndrome. A fungus, thought to have been brought from Europe by a traveler to New York, first infected bats in the northeast. An infected bat is woken up deep in its hibernation period, when no insects are available to eat, and then the bat starves to death.
White Nose Syndrome has now spread throughout much of the eastern and central US, killing over a million bats. Amid the die-off, there is some hope - those bats not affected may be able to repopulate, and hopefully their descendants will be less sensitive to the fungus.
The book Extinction, by Paul and Anne Ehrlich, introduced the
rivet popper analogy to describe the unraveling of our natural world:
As you walk from the terminal toward your airliner, you notice a man on a
ladder busily prying rivets out of its wing. Somewhat concerned, you saunter
over to the rivet popper and ask him just what the hell he's doing.
"I work for the airline—Growthmania Intercontinental," the man informs
you, "and the airline has discovered that it can sell these rivets for two dollars
apiece."
"But how do you know you won't fatally weaken the wing doing that?" you
inquire.
"Don't worry," he assures you. "I'm certain the manufacturer made this
plane much stronger than it needs to be, so no harm's done. Besides, I've taken
lots of rivets from this wing and it hasn't fallen off yet. Growthmania Airlines
needs the money; if we didn't pop the rivets, Growthmania wouldn't be able to
continue expanding. And I need the commission they pay me—fifty cents a
rivet!"
In each individual case, it's not always possible to definitely prove that pollution, climate change, or other impacts caused the die-off, or made it worse. Still, the pattern seems clear.
How many rivets will it take until the entire wing comes off?
Notes
Note on the images: I spared you the worst ones. Perhaps you'll never have to see it in person.
The rivet popper analogy, in its original presentation, applies to species extinction. I'm not aware of any specific evidence that either Sea Star Wasting or White Nose Syndrome are likely to directly result in a species going extinct. However, a large and sudden population decline of one or more species is deeply concerning for any number of reasons.
Edited:
- Added map of extent of sea star wasting syndrome, from the US Santa Cruz site.
- Added map of extent of White Nose Syndrome, from whitenosesyndrome.com