Excerpt. © Reprinted by permission. All rights reserved.
Chapter 1
Into a Watery Forest: Senses in the Sea
“I really don’t know why it is that all of us are so committed to the sea, except I think it’s because in addition to the fact that the sea changes, and the light changes, and ships change, it’s because we all came from the sea. And it is an interesting biological fact that all of us have in our veins the exact same percentage of salt in our blood that exists in the ocean, and, therefore, we have salt in our blood, in our sweat, in our tears. We are tied to the ocean. And when we go back to the sea—whether it is to sail or to watch it—we are going back from whence we came.” —John F. Kennedy, Remarks at the Dinner for the America’s Cup Crews, September 14, 1962
The anchor chain rips over the aluminum bow with a deafening rattle. When the anchor strikes the bottom of Barkley Sound there’s a sudden silence over the water broken only by the sea’s slow wash on the nearby rocks. The early morning sun hides in September overcast.
“Okay,” Kieran Cox says, stretching his arms over his head. “Here we go.”
He secures the anchor chain and then bounds toward the boat’s stern, over roll-top dry bags and milk crates crammed with neoprene dive gear and surveying equipment. The thirty-three-year-old is ruddy and freckled with a reddish wedge of beard and an athlete’s shoulders; and there’s a touch of old-school field scientist in his green fisherman’s sweater and desert boots, properly laced.
Cox moves aside a meter-tall white PVC pipe stand that he twisted together late last night in his cabin, to which he’s lashed two small black cola-can-sized hydrophones. I ask him how he turns them on underwater. “They’re on. They’re listening right now.” He grins and widens his eyes at me.
The Liber Ero—Libby for short—is a 6.5-meter aluminum research vessel and dive boat at the Bamfield Marine Sciences Centre, a research campus tucked into Barkley Sound on the west coast of Vancouver Island. Since June, Libby has carried Cox and his colleagues around the sound to two dozen underwater research sites, like this one just off a small rocky islet. More than a hundred such islets dot the sound. Their slopes are forested above the water with British Columbia’s characteristic spruce and fir, and beneath the water with kelp.
Kelp are large brown seaweeds, and two species here in the Sound are large enough to form forests, growing up to 30 meters long in towering underwater groves. Bull kelp, or Nereocystis luetkeana, is a beautifully simple structure—one long clean bullwhip stalk stretching from a netlike holdfast that grips the rocky bottom to a fist-sized hollow surface float that trails a tuft of long, rubbery blades. Its sleek structure thrives in cool high-energy water wherever waves seethe and crash. In contrast the giant kelp, Macrocystus pyrifera, the largest kelp species in the world, sports wrinkled blades all along the stem like a giant cornstalk.
Kelp forests grow along more than a third of the world’s coasts, including most of British Columbia’s. If you want to understand these temperate coastal ecosystems you need to understand kelp. These forests give structure, shelter, and food to rich groups of plants and animals. But Cox is curious about another service that kelp forests might offer: absorbing unwanted noise and preserving the soundscape.
By his own admission Cox is not an acoustician—a scientist who specializes in the study of sound. (He once described himself to me as merely “sound-curious.”) He’s an early-career marine ecologist and studies many communities under the waves in addition to kelp, from coral reefs to seagrass beds.
But Cox nonetheless needs to consider sound to understand this kelp community because like light, or temperature, we now know sound is critical for many underwater animals. For this study, his question is: How much unwanted sound—noise—do the great fronds and soft stalks absorb or muffle?
Noise from boats, ships, and other sources is increasing in more and more parts of the ocean, especially near coasts, which in British Columbia often means kelp ecosystems. At the same time, kelp forests themselves are declining. What does that mean for the soundscape in and around these forests? How does noise move through kelp? There are data gaps, and Cox is trying to fill a few.
All summer Cox has been diving into the kelp, where he surveys the forests’ inhabitants, sets out the hydrophone stands among the stalks, makes noise nearby, and listens to the recordings. Today in the stern he joins Bridget Maher and Claire Attridge. Cox is now a postdoctorate student at Vancouver’s Simon Fraser University, but earned his PhD at the University of Victoria, and still collaborates with his former co-supervisor, Francis Juanes, and lab mates. Maher is the Juanes lab manager, and Attridge is a master’s student in the same. Marine stations like Bamfield are often collaboration hotbeds between many researchers, labs, and universities.
They are all cold-water divers, as many marine biologists must be. Their hour-plus-long dives don’t allow for wet suits, the standard skintight neoprene, but instead require dry suits—bulky, waterproof garments sealed with stiff sealed rings at the neck and wrists and woolen layers beneath. This makes kitting up on the boat a project.
Cox and Attridge peel off their sweaters and step into the suits with the efficient gestures of long practice. They shrug on the heavy air tanks, attach the requisite hoses. Maher has shaved the nape of her neck so her hair doesn’t snag in the tight hood; she French-braids Attridge’s hair, hooking the long blond strands with deft fingers. Each day means multiple dives at multiple sites, and the math of scuba safety requires them to take turns so no one spends too much time down. A typical hour-long dive to a depth of 10 meters mandates a break of an hour or so before they can repeat the effort. Cox and Attridge are starting the day off.
Maher records each tank’s air levels for her lab records. Cox is bouncing.
“Can I roll off and sit in the water?” he asks rhetorically, sluicing water across Libby’s deck as he drops in. Attridge follows. She’s carrying orange flagging tape and a clipboard with waterproof paper and a pencil on a string, looking for all the world like a forestry surveyor. In a way, she is. Before each sound experiment, the team surveys the kelp forest for fish and invertebrates, of which there are many in these rich seas.
There’s a distant whoosh and a pale plume suffuses the air a kilometer away.
“Humpback,” Maher says, shading her eyes with her hand.
I’ve been carrying around a small hydrophone for the past year so I can listen whenever I visit the sea. I drop it overboard and wrestle on my earphones. There’s no whale song but I do hear heavy breathing, like someone panting. I realize it’s a diver, either Cox or Attridge, though their bubbles riffle the surface dozens of meters away. A testament to sound’s underwater range, if you have the gear to listen.
Maher zip-ties more hydrophones to the pipe stands. The divers will carry them down to the kelp forest, placing some at the outer edge fully exposed to the boat noise, the other stands 5 meters back into the fronds with more kelp between them and the sound source. The difference between their respective sound levels will tell Cox how the noise propagates through the forest and how much the kelp is absorbing. Maher caps each stand with a GoPro, to record any fish or other animals visibly reacting to sound.
One noise source Cox uses for this experiment is Libby herself. She’s of a size and horsepower with the water taxis, fishing boats, and recreational vessels that coastal British Columbians in these parts use frequently. Cox will drive Libby back and forth past the test site.
The other regional noisemakers are a local ferry, tugs, barges, and a few kilometers out, the shipping lane where cargo and cruise ships pass. Cox wants to know what these behemoths, too, sound like as they pass the kelp forest, but lacking access to such large vessels, he will instead play recordings of their passages from an underwater speaker. It’s not perfect, as a speaker can’t exactly reproduce the noise of these vessels. But it will provide some data. Maher now hauls this black, frisbee-sized disk from its crate. It’s designed to play music underwater for synchronized swimmers and connects to a simple Sony .mp3 player loaded with sound files. Maher tests it, skipping through today’s playlist: several pure tones, and an in-situ recording of a boat in these very waters.
