Fish on the sand

In the eelgrass beds at the bottom of the intertidal zone, fish dart through the thickets, usually visible only as a flash of movement, a streaking silver shape dashing from shadow to shadow, or a panicked thrash to escape my clumsy foot. They're usually not the fish I see in the upper zones, the sculpins and the flatfish, but they speed away so fast that I haven't been able to recognize any.

This last trip to the low tide line, though, the shallows were littered with dead and dying small fish; I was able to identify three species.

Another Pacific sand lance, Ammodytes hexapterus. These grow to about 11 inches long, so this is a youngster.

In one small area, I counted over 50 of these, all dead, but still fresh, surprisingly still untouched by gulls or crabs. They were all young; the adults spawn and die in mid-winter here. I am wondering what caused this die-off.

A larger sand lance, still alive, but barely. The back is a glittery blue-green, which should help with camouflage in the eelgrass beds, at least from above. At night, they burrow into the sand, to hide from predators.

Mixed with the sand lances, a few darker, larger fish stood out.

Pacific snake prickleback, Lumpenus sagitta. About 8 inches long.

Another. This was still alive, but not able to swim away.

Again, these were young fish; the adults grow to 20 inches long and spawn in the winter.

One more; a beautiful singing midshipman, no longer able to sing.

A steampunk fish, looking as if he were made of riveted plates. Plainfin midshipman, Porichthys notatus, about 8 inches long.

These are night-swimming fish; during the day, they hide under rocks. I found a male, guarding eggs, about this same time three years ago, under a rock at the boat launch. He was fatter and longer than this one.

The "rivets" are lines of photopores, cells that emit light. They may help to attract prey at night. (Although we don't really know that; it's human speculation. We do like to imagine that we understand Ma Nature.)

Belly up, showing the pattern of photopores, and his delicate colouring.

Zooming in to the tail end, to show the little lights, and - look closely - tiny waving three-fingered hands, all in a row.

I didn't pick this one up; some midshipmen have poisonous spines. I'm not sure if this species does, but I'm not risking it.

And I'm left wondering why all these suddenly showed up dead, all at once. The water was clear, it smelled fresh, there was no scum or oil sheen. There is construction going on 'way back at the shore, but that's a full kilometre away. Worrisome.

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.