7 Aug 2011

Clam Gardens

The practical skills to handle small boats have real-life applications for modern work in the sciences. One field that puts canoes and kayaks to serious use is... intertidal biology! This summer, as a volunteer assistant, I joined a biology project. A friend in Straitwatch passed on an appeal from a biologist for volunteers to stay at an isolated campsite on Quadra Island, and take samples from beaches. Paddling skills were needed, so I brought my little kayak. I joined three other volunteers and Amy Groesbach for five days on the shores of Waiatt Bay, a sheltered inlet with several small islands that make up Octopus Islands Marine Park. Amy Groesbach took these photos. To see lots of pictures of how she and her mentors investigate traditional First Nations clam gardens, go to her Flickr page and check out her photo galleries for those labelled "Clam Garden 2011 - Trip 1" through Trip 4. And here's Amy holding one of the squares she made out of 1-inch PVC tubing, so we could dig holes exactly 25 cm across. We had to dig them 30 cm deep, which is exactly the length from my elbow to my knuckles. In a few beaches, there were experiments placed where Amy buried hand-made mesh bags holding living clams, and retreived them later. I learned how to make a sampling device. A kitchen scrubber called a Tuffy was attached to a ten-inch piece of rebar with a cable tie. Easy as pie. After the rebar was pounded into a clam garden, the Tuffy would collect clam spat. Intertidal biologists have been inventing devices to collect clam spat. Someone tried using kitchen scrubbers, and found the Tuffy brand was particularly effective. The fun part is pounding the rebar into the garden, when the pounding has to be done underwater. Smack! Smack! into the water. "Science! Doing it all for science!" Spit out muddy sea water. "I'm still having fun!" The first time we catalogued clams, both living clams and the shells of dead clams, our group gathered under the tarp over our kitchen area. Seated on five-gallon pails, we hunched over our shells. A rain squall fell around us, and we got chilled and stiff before we were done and dinner could be made. The second time was a sunny afternoon, so after lunch on a rocky slope below a midden across the bay from camp, we set up the calipers and notebooks. Each of us moved into the shade or sunshine at will. Our postures were not hunched this time, but varied from leaning on one elbow like a diner at a Roman feast to laying back against rocky slopes perfectly designed to support our backs and heads. Looking out across the bay was wonderful. I'd always thought that doing science involved wearing lab coats, not bathing suits or my shortie wetsuit. This place was much nicer than a basement lab somewhere. If you look over a clam garden at high tide, from a boat or from the shore, you probably wouldn't see anything to tell you that this is a place shaped by human gardeners. When the tide is a little lower than full, you might guess at the shallows near shore, usually in a small bay or between two rocky points. But when the tide is low, approaching a zero tide, the clam garden is revealed.

From shore it looks like a flat beach, mostly free of rocks bigger than your head. Most of the beach is sediments mixed with small stones and bits of broken clam shell. The shell hash was added deliberately, to send chemical messages to floating clam spat that here was some good clam habitat to settle down and grow! At the edge of the garden is a rocky ledge. Most of these ledges are maybe ankle-high. But if you look past the edge of the ledge, you can see that the sea bottom drops down suddenly. You're standing at the top of a wall made of rocks piled on rocks, four or five thousand years ago or more.

To learn more about traditional clam gardens, check out the book Clam Garden by Judith Williams. You can read more about it at the publisher's website.

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