This past Tuesday and Wednesday afternoon I took my marine biology students to the rocky intertidal at Natural Bridges State Beach. We completely lucked out with the weather; the storm system that brought some of the rain that we desperately need had cleared out, leaving calm, clear seas and little wind. Perfect weather for taking students out in the field, in fact.
First of all, we didn't see any stars. Not that I was looking for them, particularly, but I was keeping an eye out for them and at this time last year I would have seen many Pisaster ochraceus hanging out in the pools and on the rocks. Here are a couple of pictures I took at Natural Bridges in years past:
The stars, when present, are prominent residents of the mid-intertidal zone, where they feed on mussels. But now, alas, there don't seem to be any. They WILL come back, and it will be interesting to monitor their population recovery.
I enjoy taking students in the field because many of them have never been there before, and it's always fun looking at a familiar scene with fresh eyes. When everything is new, it is very easy to be excited and enthusiastic, which these students are.
Yesterday I heard (or, more precisely, was reminded) that the quinine molecule fluoresces. Fluorescence is what happens when a molecule absorbs electromagnetic radiation--either in the visible light range or elsewhere in the spectrum--and emits light at a different wavelength. Lots of molecules fluoresce. Chlorophyll, for example, is the green molecule that captures the light photons that power the process of photosynthesis. If you shine light at a wavelength of 425 nm (violet) at a tube of chlorophyll, it will fluoresce, or emit light at 680 nm (red).
Here's a DIY video guide to demonstrate the fluorescence of chlorophyll in the comfort of your own home:
So back to the fizzy beverages. I sing in a choir that has a long tradition of gathering after rehearsals and drinking gin-and-tonics (G&Ts). Tonic water contains quinine, which imparts fizziness and a certain bitterness to the drink. Having re-learned about the fluorescence of quinine, I thought it would be fun to watch the tonic and gin mix under a UV light. We needed a dark place for this experiment, hence the bathroom, the most convenient room that we could completely darken.
Turns out it worked amazingly well. Tonic water is entirely clear under white light, which contains all wavelengths of the visible spectrum; it looks like any other unflavored fizzy water. But under the UV light it glows with a kind of unearthly blue hue:
But the real fun is in watching the tonic and gin mix in the glass. We make G&Ts this way: Put a few ice cubes in the glass, squeeze in a bit of lime, pour in two fingers' of gin, then top off with tonic water. So we did everything but pour in the tonic water, then ventured into the bathroom with the UV light, where I recorded this:
"Perhaps" being the operative word here. I was up at Davenport Landing the other day to do some collecting, and saw some healthy stars. Alas, no pictures, as I'm not coordinated enough to do photography and collecting on the same trip. But here's what I saw:
5 healthy Pisaster ochraceus stars. This was the first species to start melting in my seawater table back in September, and they've suffered a lot subtidally as well. These five were all at least as big as my outstretched hand, so were several years (decades?) old. They were nice and stiff, unlike the flabby ones that died, and firmly attached to the rocks, indicating that the water vascular system was functioning normally. Yippee!
6 healthy Dermasterias imbricata stars. I haven't personally observed this species being affected by wasting syndrome, and the stars I saw the other day all looked good. This species as a whole does not have the sticking power of P. ochraceus, but the ones I picked up had the right texture and consistency to make me think they were in good shape.
1 tiny Pycnopodia helianthoides, about the size of my thumbnail. It had 10 arms of various lengths and was very active. I really wished I had my camera when this little guy floated into view on a piece of algae.
So what does this all mean?
Probably not much, in and of itself. This is a single observation at one site on one day. But finding live, healthy stars is a lot more encouraging than seeing only dead or dying stars. The fact that I saw a very small P. helianthoides makes me wonder. Usually at Davenport Landing I see a few hand-sized or larger Pycnopodia stars. . . I saw none the other day, so does that mean they've all died? And how old is this little 1-cm star? Did it recruit before or after the wasting event?
I also noticed something else, which may or may not be related to the recent star deaths: Turban snails (Chlorostoma funebralis and C. brunnea) seemed to be more abundant than usual. Also, the C. funebralis, which are typically roughly spherical and the diameter of about a quarter, were larger and had the more slightly conical shape of C. brunnea. Just a coincidence? Hard to say, without quantifiable data, but I'm guessing "Yes."