Sunday, July 27, 2014

Looks like grungy tapioca pudding

The web is well named; Google is a net designed to trap you, a net full of bait and with unexpected hooks, until you're flopping like a salmon in the hold of a fishing boat, not knowing where you are, or how you got there. ... Where was I?

Oh, yes, double-checking info about the foam piled up along the beach in Boundary Bay. I promised to write about it yesterday, but then I dropped in on Google. Did you know it's illegal to catch octopuses in snares in BC coastal waters? Nor did I. Nor that fishing for ghost shrimp is a thing.

Along the way, I collected a bucket-load of acronyms from NOAA, itself more known by the acronym than by its unwieldy name, National Oceanic and Atmospheric Administration. And goggled at photos of whole towns engulfed by wind-blown foam.

Anyhow. This was about the foam. On our beach.

It looks like tapioca pudding with too much vanilla and green string. YMMV

This stuff piles up in a border about one or two feet wide all along the high tide line, from as far as I can see to the north and to the south. When the water recedes, it dries and disappears, leaving only the tangle of eelgrass and a coating of scum.

I find it rather off-putting; icky is probably a better word for it. When the wind blew my hat into the foam this week, I stuffed it in a plastic bag. At home, I soaped and scrubbed the hat so thoroughly that it lost its shape. I ended up tossing it in the trash.

And yet, I know that this scum is no dirtier than the sea water I wade in on the incoming tide. The brown tinge is probably from fine particles of the black, rotting eelgrass that lies in mounds above the tide line. As the foam comes in, it's white; only as it hits the shore does it turn brown.

Clean foam meets the shore.

The foam is caused by dissolved proteins and fats, the remains of dying seaweeds and dead critters, plankton and algae. They act like detergents, and have the same foaming action when the water is stirred by wind and waves.

Waves rolling in from a choppy sea in Boundary Bay last week. As they broke near the shore, they created suds.

Most sea foam is not harmful to humans and is often an indication of a productive ocean ecosystem. (From NOAA)

Here in the southwest corner of BC, we see foam most often in the summer months, when the water is teeming with the planktonic young of hundreds of species of ocean dwellers, when the sand is dotted with egg cases of lugworms and the eelgrass lined with assorted egg masses and ribbons, when the kelp forests are growing to their summer height; and when most of the frantic production of the next generation is bound to fail and to add to the dissolved protein in the water.

Lugworm egg case, about 4 inches long. Many of these dry out and die at low tide; this one is still in an inch of water.

Even when the water is calm, we get summer foam. These next two photos are from last July, on a rising tide.

Boundary Bay, from the eelgrass beds, facing Point Roberts.

Gobbets of foam floating inland with the tide.

But what about my worries about the ickiness of the foam? Don't we hear about shellfish poisoning and noxious fumes associated with the foam? Well, yes. But this is rare, or has been up till now. As the oceans warm up, and we pour more contaminants into the ocean, the hazards may multiply. But as it is now, the foam is mostly a sign of a productive ecosystem.

When there is a large die-off of an algae bloom, some of these algae release toxins into the water. These are taken up and concentrated by shellfish, especially mussels, super-efficient filter feeders. And when humans harvest and eat these contaminated shellfish, we get sick, sometimes fatally.

BC is home to the algae ultimately responsible for Paralytic Shellfish Poisoning (PSP). I have seen signs beside the access points to our beaches warning of this; all harvesting of bivalve molluscs (clams, mussels, oysters, etc.) is prohibited in the Lower Mainland. People still go clamming, and I haven't heard of any poisonings, but it's always a risk.

Clam diggers on Boundary Bay, getting the last of the catch in before the tide wipes out their sand bar.

Sign by Fisheries and Oceans Canada

I'm sure PSP was known to BC's First Nations from generations back, but the first documented cases (at least by Europeans) were in 1793:

British Columbia (B.C.), the Pacific province of Canada, has one of the longest documented histories of the severest form of harmful algal blooms, paralytic shellfish poisoning (PSP), along its entire 27,000 km coastline. The first documented case was in 1793 when four of Capt. George Vancouver’s survey crew became ill after a meal of mussels while charting the central coast (Mussel Inlet, originally named Mussel Canal, a side-arm of Mathieson Channel; see Fig. 23*). The location where they had the toxic breakfast of
mussels was named Poison Cove by Vancouver. One of them died five and a half hours later and the location of his burial was named Carter’s Bay.

(Taken from Harmful algal blooms in western Canadian coastal waters, by F.J.R. “Max” Taylor and Paul J. Harrison, UBC.)

* Near Bella Coola, Central Coast.

Today, various government agencies, such as NOAA in the US, Fisheries and Oceans Canada, and the Canadian Food Inspection Agency (CFIA), monitor our waters and shellfish for possible contamination, and issue warnings. As long as we pay attention, and eat only shellfish from safe sources, we can slosh about in the water to our heart's content, foam or no foam.

Most sea foam is not harmful to humans and is often an indication of a productive ocean ecosystem. (From NOAA)

1 comment:

  1. Vasha5:31 pm

    I've seen this stuff here on the East coast but never very thick. Sometimes it's very yellow in color... Different local algae maybe? By the way one of your links people really need to read so I'll repeat it:


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