Underwater epidemic

Or, The rotten egg zone, Part II
(Part I, yesterday)

The bad news first.

The starfish are dying.* Up and down our coast, from California to BC, millions of starfish and sunstars are curling up as if in agonies, losing arms, and then quickly dying. The cute little brittle stars are infected; sea cucumbers are spilling their guts and rotting. No-one seems to know precisely why.

Affected sea stars typically first contort and twist, and white lesions appear on their bodies. Their usually firm, meaty bodies deflate and waste away. Arms fall off and walk off on their own. The animal loses its ability to hold on to rocks or pilings. Its body falls apart in pieces, and finally dissolves. Within weeks, only a ghostly white print will remain, and then nothing at all. Entire communities are wiped out, as if they never existed, (SeattleTimes)

(Stories, USAToday, SeattleTimes, PBS.)

One of the scientists trying to find out what's happening, and why, is diving photographer Jan Kocian, co-author of a Reef2Rainforest blog. I found an article there, about a series of dives in Puget Sound, off Whidbey Island, just a short distance south of here,

. . . with the objective of obtaining photographic evidence of, particularly, the sea-star wasting disease epidemic . . .

He discovered masses of dead and dying brittle stars. It's a gruesome read, and the photos are frightening, but if you can stomach it, it's worth the effort.

Here's the gist of it, though: Kocian made a series of visits this September, finding sick sea stars, then dead sea stars, dead clams, dead and dying sunfish, dead sea cucumbers, dying sea urchins, worms, and more. By the end of the month, some areas seemed to be recovering after a storm which cleared the water, but further off-shore, the carnage continued.

The full extent of the dead area, and the reason for the mortality, remain indeterminate. Typically in Puget Sound, the benthos is very rich, so that a mortality event such as this may take several months for even partial recovery.  Although the substrate will appear to recover in a few months, quantitative sampling will show the benthos make take two or more years before it has returned to normal.

Many scientists studying this believe that it may have something to do with the increased temperature of the water; even a portion of a degree, on average, can have a major effect, stressing the animals and promoting the growth of bacteria. (I read on another website that some sea stars recovered when the temperature dropped.) Or it could be a bacterial infection, an underwater epidemic. Or ...

The cause could be a toxins, a virus, bacteria, manmade chemicals, ocean acidification, wastewater discharge or warming oceans. "We're not ruling anything out," Raimondi said. (USAToday)

I've found a few dead starfish on the beach at Boundary Bay recently, but they had all their arms, and their deaths were probably, I hope, due to more usual causes. And the stars that came home with me a few weeks ago seemed healthy. I keep hoping.

Ok. Now the good news.

After reading all this, I examined my three mottled sea stars carefully. They look fine. They're eating and growing and making a general nuisance of themselves. I don't see any early lesions, but I'm making sure to keep them cold and change their water frequently.

And I found the answer to a question I've been asking. As Ron Shimek, Kocian's colleague writes,

As is often the case in a study such as this, serendipity will rear its head, and wholly unexpected observations will be made.

And I'll leave my discovery for tomorrow.