Friday, August 21, 2009

Water garden

(Edgewater beach series, cont...)

Down near the water's edge, where the rocks never dry out, even on hot days like these, the beach takes on a different character. Here, a little bay forms, shielded by an outcropping of rocks on the north ...

Layers of sandstone and a big rock fallen, long ago, off the cliff side. And a "lawn" of fine algae, a slippery coating of green scum on the rock.

... and to the south, a herd of sea lions turned to stone. Medusa lives!

In the bay, a jumble of large, irregular rocks forms the base for a garden of seaweeds.

"Zone 5". Rockweed and sea lettuce.

Rockweed, barnacles and an oyster.

No monoculture in this sea garden; every few steps brought a new seaweed. Some were old favourites, like the Turkish towel; others I couldn't identify. Still can't, even back home with my handy "Marine Life of the Pacific Northwest". There is a tiny, reddish-black, hairy plant that covers the bottom of the shallow pools, fine hairs tangled around the base of rockweed, a red "tar" on rocks. Some of the rockweed has enlarged, distorted, blistered branches; whether this is sunburn or an infestation of some kind, I don't know.

Blistered rockweed.

A small Turkish towel, and rockweed. The rockweed seems to be smaller than our Lower Mainland variety.

A feathery, yellowish frond floating in the shade of a boulder.

Red algae. The white part has been sunburnt. The shaded bottom is a deep burgundy. With sea lettuce.

And bull kelp. I am always intrigued by these giant plants, so soft and elastic, so alluringly coloured. A smallish one was floating close to shore; I waded out and dragged it in.

I stretched it across the beach, to see how far it reached. See that yellowish spot 'way at the top of the photo? That's the holdfast. The fronds still reach a couple of metres behind me into the water.

I love the holdfasts; fist-sized grabbers, as tough as wire. They feel and look like molded plastic; they don't bend easily, and I can't break them with my hands.

Kekp holdfast, entangling a large, feathery green seaweed, unidentified.

Holdfast close-up.

Two holdfasts, intertwined. We pulled at these, Laurie and I; we couldn't separate them.

We've seen these little "blobs" (we have no better name for them)* at Boundary Bay. There were large patches on this beach. They are up to about two inches across, shiny, have no stems. A few were broken, showing an empty centre space. Some were floating in the water.

There are a few similar seaweeds in the Encyclopedia, but nothing quite matches.

Mystery blobs.

*Update: tentatively identified as Leathesia difformis, the sea potato or sea cauliflower. (See comments.)

One other thing; stand still and look at any patch of seaweed. It's moving. Not the underwater plants, which move with the water; the ones out in the air, too. They vibrate, jerk, bend. Look closely; they're alive with tiny animals. Snails, isopods, crabs (some so tiny we don't see them until we enlarge a photograph), hermits, worms; all in busy motion.

The jumble of rocks peters out; the ones remaining become islands in a shallow basin with a flat, sandy bottom. The water is cool and transparent. We wade out to see those rocks the seagulls were sitting on.

But I'll leave that for tomorow.



  1. On the "mystery blobs": texture-wise, they look like they could be some kind of Codium, a green algal genus that includes both blobby forms and upright branching forms. One of the cool things about Codium is that even though it can get quite large (over a metre for the branched forms, IIRC), it's technically unicellular - instead of being divided into separate cells, it's made up of twined filaments.

    Another (less likely, I suspect) option is that they may be oyster thieves (Colpomenia). Oyster thieves are bladder-shaped brown algae that get their name from when they grow on (amongst other things) farmed oysters. The bladder fills with gas as it grows, and may eventually contain enough gas that it floats off, carrying the oyster with it.

    Or I'm sure there's plenty of other things they could be. I'm hardly an expert on seaweed.

  2. Christopher, you are always so helpful! I couldn't find a Codium to match, but the Colpomenia was pretty close, and they are found in this area. But, Googling the Colpomenia images, I found Leathesia difformis, which does match and is found all around Vancouver Island. The clincher would be to tear a piece and see if it is slimy; Colpomenia peregrina would not be. I'll do that next time I find some.



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