You are what you eat

Northern winters are tough on the little beasties that live at the intersection of sea and shore. Temperatures change, often drastically, in the course of a few hours. Storms toss whole colonies up on the beach, bury them in mounds of slimy, rotten eelgrass, drop logs on top of them. Cozy shelters in the seaweed are stripped bare; on the scoured stones, there is nothing left to eat, nothing to hide a scuttling crab from the myriads of hungry birds following the tide line.

My tank critters are spoiled. The temperature stays put; so does the water. Food drops from on high every day. There are no birds, and the cat doesn't relish getting wet.

Grainy-hand hermit on the remains of a kelp holdfast.

But even here, winter brings its losses. I comb the beaches year-round, searching for salad fixin's and gym equipment for the hermit crabs. In summer, there are bright sheets of sea lettuce, tall stalks of eelgrass, some loaded with delicious hydroids and diatom fuzz, knobbly Turkish towels and washcloths, long, green hair, stubby rockweeds, and more. But in winter? Bare stones, washed-out shreds of unidentifiable weeds, stripped of anything edible. And tea-leaf black, dried eelgrass.

In earlier years, the tank in winter gradually lost all its greenery, until the hermits wandered about disconsolately on bare sand and stone. I supplemented their diet with human food, sheets of green algae meant for sushi wrappings. They liked that, but it fouled the water.

The last couple of winters have been different. A red sheet algae established itself in the tank, and now grows as enthusiastically as the land plague, Himalayan blackberry. I have to keep cutting it back with every weekly water change. But at least there's something fresh to eat, and somewhere to climb.

Red algae is even trying to grow on the hermit's shell.

The change in diet has influenced the colours of some of the tank's residents. Red are redder, greens are browner. The colour of the shrimp's innards changes day to day, depending on his last meal; red today, transparent tomorrow.

And even the normally transparent copepods are striped with red and yellow. Look closely at the hermit above; there are a dozen copepods visible on his shell.

Three females with eggs, one male; the rest, I can't tell.

Most copepods have one red eye, a streamlined body, and a forked tail. The females carry their eggs around behind them; usually one pouch (Order Calanoida), sometimes two (Cyclopoida), one to each side. In the dark one at the lower left, the pattern is easy to see; red eye above, green bag beneath. The small, pale copepod at upper left may be a male of the Cyclopoida; his long, forked tail is just visible.

Drawing adapted from one by Jesse Cladgett.

On Saratoga Beach, 2010

Laurie and I explored Saratoga Beach in the summer of 2010. This week, it was bare and empty. Back then, it was teeming with life.

I hadn't taken many photos of the beach critters, being more taken that day with the shapes of old stumps. But I found a couple, for comparison.

8 or more crabs, 2 (at least) hermit crabs, several limpets, a tribe of periwinkles, assorted clamshells, and barnacles, all coated with green algae. In a couple of hand-breadths of the gravelly spit.

Helmet crab carapace.

Looking south towards the spit in 2010. The previous two photos are from this area.

Over on Facebook, Fred Schueler was suggesting possible causes for the disappearance of all that life:

It could be from abrasion after really severe storms, maybe combined with winterkill - we were on Haida Gwaii for two winterkills-1985 and 1988 - and the first was mostly big rock-clinging invertebrates and the latter mostly fish and crabs - in 1985 folks were eating Octopus, and in 1988 Dungeness Crabs - the big slow-growing invertebrates just hadn't had time to recover in 3 growing seasons.
...or maybe rather than abrasion the spit had been buried in sand for a couple of years?

Or it could be just a feature of that tiny area of the beach. Or everything has dug in deep because of the weather. Or a slight change in the average temperature; climate change, in other words.

More investigation is needed.

They are what they eat

It's wet and rainy, and the days are dark. Our weather people tell us to expect 2 hours of sunshine tomorrow. Watery sunshine it will be, at best. My garden is mourning.

Down on the beach, the seaweeds we see all summer are gone, ripped up, dead, or in some sort of hibernation. This last visit, I found one shredded piece of sea lettuce, one rotting rockweed. But the high winter tides and the storms brought in large sheets of Turkish towel, and two different red algae, which I've planted in the aquarium.

And all my critters are eating red veggies, and turning pink, to match their new diet.

One of the red algae, growing on an old clamshell.

One of the little white-fleshed (normally) Nassa snails, between two different red munchies. Only his siphon retains the usual hint of cream.

One of the little orange hermits, now sporting pink and violet tones around the mouthparts.

The crabs refuse to eat that red stuff; they're still green and white. Or grey and black, in the case of the tiny black-clawed crabs.

In a bag full of holdfasts

In winter, along the high tide line in Boundary Bay, most of the washed up plants are eelgrass, torn out of their beds halfway down the beach. Occasionally, there's a scrap of Turkish towel and a blade or two of sea lettuce. Not much else.

But the recent windy weather has been working on the kelp forests in the deep water at the centre of the bay, and on Friday, the eelgrass rolls were tied around stipes and blades of several varieties of kelp.

Floating bull kelp bladder, with attached fronds. All very scratched and beaten, from rolling up the beach.

Torn blades of sugar-wrack kelp.

I collected a few blades of a smaller kelp, and all the holdfasts I could find. There were no bull kelp holdfasts; the weather is still too mild to damage them. All the holdfasts were of the smaller varieties of kelp, and attached to shells and stones. I planned to put a few of these in the tank for my critters to play on; the rest would be interesting to examine to see what was living there.

Small holdfast, on clam shell. Probably a sugar wrack kelp; the stipes are only a few inches long. (Bull kelp stipes may be over 100 feet long.)

At home, I put my haul in a big bowl of sea water, and watched to see what showed up. Plenty of worms and amphipods, of course, but there was much more.

Here's one of the smaller residents:

Pale pink baby starfish!

More tiny treasures tomorrow.

The lettuce eaters

Winter in the intertidal zone is difficult, even here where it barely gets cold. The water is often turbulent, the nights are long, the daylight dim. The plants and algae, the seaweeds and eelgrasses, die back, leaving no shelter from the flocking thousands of sandpipers foraging in the shallows.

We see little more than worm tubes and holes, snails, those everlasting invasive Asian mud snails mostly, and the hermit crabs that use their abandoned shells, fewer hermits than we would see in warmer weather. Many don't make it through to spring.

My tank residents have it easy. The temperature stays the same year-round. The current rarely changes, except when I'm cleaning the pump. There is daylight 16 hours a day, always bright, never clouded over. And there are no birds. No birds!

The one small bump in this easy road is the intermittent supply of greens. Often, on a trip to the beach, I manage to bring back only a few handfuls of skimpy eelgrass and a bit of half-dead kelp. It's rare that I find sea lettuce for them in the winter, or Turkish towel that isn't all torn and rotting. Sometimes their tank is almost empty of vegetation; when I then bring the hermits a mess of hydroid-covered eelgrass, they climb on it and never leave until it's bare.

This winter has been exceptionally hard for them; they have been getting a small taste of what their cousins on the beach go through every year. What with one thing and another, the weather, and the state of our health, and other time constraints, we haven't been down to the beach since mid-February. I did bring back a couple of pieces of fresh sea lettuce then, and I found a big leaf of fresh Turkish towel, which lasts well in the tank. But there was little eelgrass to go with it, and no replacements since then. The tank is bare; an underwater desert, decorated with small shreds of fading Turkish towel, stripped of any food value.

One of the smaller hermits, on a barnacle-covered stick.

I read somewhere that hermits will eat ordinary people-food lettuce. Worth a try; I tore off a bite-sized piece and anchored it in the sand. Within a minute, the largest hermit and the crab were having a tug-of-war over it, yanking and pulling and at the same time tearing off pieces and shoving them into their mouths. (It's handy having so many grabbing mouth parts.)

I added a few more pieces of lettuce for the rest of the crew. That was a couple of hours ago. They have eaten it all, leaving only a few floating shreds, as thin as soggy tissue paper.

Hermit on lettuce leaf, all stretched out to grab as much as possible before the rest get there.

Hermit on the far side of a scrap of lettuce. His shell is showing through the hole someone has already torn.

As far as I can tell, all the hermits got a chance at the lettuce. The largest one stuffed himself so much, finishing off one piece and going to the next, and the next, that I wonder how he fits into his shell now.

I saved a leaf for them tomorrow; I ate the rest.

Hurry, hurry! Dinner is served!

I wonder if they like cilantro? I've got a big, fresh bunch.