January junkets

the force of ice, and a leisurely beach walk

The Fish Creek trail, going upstream from the Douglas Highway bridge, was –as expected—very icy in spots, with occasional little rivers flowing in it. Biologically, things were pretty quiet. The cool story was the ice along the creek. Impressive ice jams had built up in several places, piled on rocks or backed up behind stacks of logs. The cakes of ice were about eight inches thick, and they ranged is size from great plates ten or twenty feet across down to crumbs (relatively speaking). In some places they were layered on top of each other; in others they were stacked vertically against logs or streamside trees.

The creek flowed well within its customary banks. But it had obviously been more than three feet higher a day or two before our visit. Numerous cakes of ice had been carried into the small floodplain that’s just over the first ridge, as much as fifty feet from the creek banks. Chunks of ice littered the trail itself. It seemed odd that all those traveling ice cakes had not left scar marks on the mossy tree trunks, as the water carried them overland.

As we paused just where the trail starts the real uphill route toward the Eaglecrest road, one belated ice cake came floating by, twirling gracefully around partially submerged boulders. We noticed that, under the flowing water, the bottom of the creek appeared to be encased in another layer of ice. How do small fish and invertebrates survive under there? Even if they can tolerate freezing (as some stoneflies can), is there enough oxygen? How long can they go without feeding?

One mild, gray day, Parks and Rec hikers strolled out the Crow Point and the scout camp. Once past the icefalls and frozen puddles in the forest, the beach walk was easy. The north end of the beach showed distinct lines of shells left by several high tides. In particular, we noticed thousands of small, pink clam shells, many of which still held occupants, apparently.

The small, pink clams are called Macoma baltica. These clams move around the intertidal and subtidal zones, mostly at night. Typically, they live buried in the sands, using their siphons to suck up detritus from the water or from the surface of the sand. Flatfish graze on the siphons, and clams with shorter siphons have to live closer to the surface, in order to feed. Shallowly buried macomas often take in more food and grow faster than deeply buried ones, but at a cost: the shallowly buried ones are more susceptible to predation by birds. Macomas can regenerate their siphons, particularly if their food is abundant. But if there is little food for the clams, they are more likely to crawl on the surface, where the predation risk is high.

Did these windrows of macomas mean that they were torn up from the sands by recent storms and stranded at high tide? Or waves washed them up at night while they were engaged in their nightly movements? Or food was scarce, so they were on the surface more often?

Waves continue to eat into the sandy berms at the upper side of the beach. Great clumps of grass have caved in, exposing long-buried decaying logs in some places. Otters had gamboled up and down the beach, leaving their distinctive footprints. In a zone where black sand lies atop the ordinary sand, we found a set of otter tracks that I think may be the best I’ve ever seen.

Lunchtime, as we leaned back against an eroding sand bank, brought us two entertainments. As usual, a raven came in to scavenge crackers, bread crusts, and even bits of apple and orange. (No cheetos today!) All the while, another raven (?its mate?) called from the trees behind us. The bolder bird cached all its scavengings in different sites at the edge of the forest.

The second amusement was of human origin. One hiker discovered a plastic bottle with an enclosed message, assorted odd objects, and a dollar bill! The message was written by some kids at the camp in 2007, who provided their email addresses in hopes that the finder would notify them. We’ll see if they answer the notification, or if they have just outgrown their earlier game.

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