Blowtorching Seaweed for Science
Experimenting in the intertidal to investigate how species recolonize after a disturbance.
As legendary Canadian Joni Mitchell observed, you don’t know what you got ‘till it’s gone. It is this principle that finds me on the shores of Calvert Island before dawn, blowtorching seaweed off the rocks.
This isn’t a random act of pyromania. I’m helping Hakai Institute researcher Patrick Martone set up an experiment on a type of seaweed called coralline algae: red seaweeds that fortify their structures with calcium carbonate. They can take many forms, including small pinkish fronds, stiff as starched lace, as well as crusts that look like wads of old bubble gum. Unfortunately, catching them above the water means waking at 4:30 a.m. to work during June’s extremely low tide. Martone explains the experiment as we trudge to the shore through dense salal and pillow-y sphagnum moss.
“Coralline algae are often ‘first colonizers’ that provide habitat,” he says, noting that bacteria living on them give off a scent of “home”, which attracts other creatures such as baby shellfish, snails, urchins, and even other seaweeds. “When it’s not there, we think there may be less colonization. But, we’re not sure.”
At the shore, Martone directs the team over the barnacle-encrusted rocks toward bolts drilled into the granite. These bolts mark ten plots, each containing three small squares the size of ‘45 record albums.
Today, we’ll leave one square in each plot untouched as a control and completely clear the other two right down to bare rock. One will reassemble without any further disturbance, slowly re-accumulating algae and animals. From the third square, field techs will diligently remove the corallines every month. From this experimental setup, we can learn more about the role corallines play in assembling an intertidal ecosystem.
The intertidal zone teems with life. They lie beneath massive, dark, glossy ribbons of kelp strewn across the rocks like videotape on the cutting room floor. I clear the kelp; ripping its holdfasts from the rocks, then start on the corallines with a wire barbecue brush that removes everything but the crusts. For crusts, we need a hammer and chisel, and soon the rocky ledge rings with dull clinks.
After three hours, the plots are clear. Before a rapt audience, Martone lowers the blowtorch to the last stubborn coralline crusts, and they crisp slowly to white ash. It’s just in time: the tide is creeping back up, bringing the first wave of new colonists.
Corallines live worldwide—Calvert Island alone hosts at least 30 species, many new to science. Their stiff mineralized structure helps corallines grip the rocks in pounding ocean waves, and makes them good infrastructure around which diverse communities can assemble. Martone says that in the future corallines might not be as healthy or abundant as they are now, thanks to ocean acidification, a major symptom of climate change. It’s hard to accumulate minerals in corrosive water. If corallines decline, he worries that marine communities may suffer as a result.
Martone has an additional motivation to study corallines. Much of our knowledge of corallines comes from renowned intertidal ecologist Bob Paine, best known for pioneering the idea of keystone species. Martone first met Paine after winning a coralline-algae-encrusted puck from one of Paine’s experiments at an auction. Martone was a graduate student then, nervous to meet someone he admired.
“Before I had a chance to do anything, here comes Bob Paine,” Martone recalls. “[Bob]’s 6’7”, running across the ballroom, he came over and sat down right next to me and he was so excited to talk about the corallines. That sums him up. He was so enthusiastic…he was always a big inspiration for me. He just noticed all these really neat associations that the average person would overlook.”
Martone tells me this story several weeks after I joined him for the seaweed clearing. He had just learned that Paine had died the day before. “I’ve been thinking about Bob Paine a lot the last few months,” Martone says. “This is his kind of experiment.”
Several weeks before Paine’s death, Martone sent him a draft of an upcoming paper describing Crusticorallina painei, a new coralline species found at Calvert Island that Martone and colleagues named after Paine. Martone says that despite his illness, Paine was typically enthusiastic. “He was tickled.”
Ami Kingdon is an associate editor at Hakai Magazine, which is also funded by the Tula Foundation. She was visiting the Calvert Island Field Station to learn more about Hakai Institute research. Hakai Magazine is an editorially independent publication covering science and society on the world’s coasts.