Study of undersea canyon’s micbobes may offer insights

Geobiologist Victoria Orphan stands at the stern of the research vessel Western Flyer, watching her colleagues put the last touches on an unusual spread. Among the offerings: a large turkey leg, an alligator head and bowls of gelatinous agar that resemble consomme.

This meal isn’t for the ship’s crew, though. It’s bait.

The entrees are anchored to a plastic grid and pushed overboard so they will sink into the deepest underwater canyon along North America’s west coast.

The scientists check the attached camera, which will spy on the creatures that show up to feast— fish, worms, crabs and microbes too.

The microbial denizens of Monterey Canyon are far different from many of their surface-dwelling brethren. They make food out of rocks and dead debris and harvest energy from methane that seeps from the ocean floor. To survive in this dark, high-pressure, low-oxygen, low-nutrient environment, they form all kinds of cooperative relationships.

Orphan adjusts an agar bowl’s position and then heads back in to check on the tube-shaped samplers she’ll use to collect microbe-filled sediment.

“They’re not quite as exciting as alligator heads,” she says.

Orphan is being modest. Her study of these “extremophiles” may offer insights about the evolution of life on Earth—and guide the search for life on other planets. Her work earned her a MacArthur Fellowship, also known as a “genius” grant.

Much of her research takes place at Caltech, where she runs a lab with dozens of graduate students and postdoctoral researchers. But expeditions like this, miles off the California coast in Monterey Bay, are a crucial part of her work.

Orphan is co-leading this trip with Shana Goffredi, a biologist at Occidental College who is also her life partner. Where Orphan studies microbial alliances, Goffredi explores the relationships between microbes and larger animals such as clams or snails.

Alligator heads and turkey legs are small fry for this crew. About a decade ago, Goffredi and other scientists at the Monterey Bay Aquarium Research Institute towed the carcasses of dead whales out to the canyon and released them at different depths. The result was an enormous experiment that shed light on the complex population dynamics of these deep-sea communities.

Just as wildflowers blossom in the barren desert after a storm, long-dormant microbes bloom on a “whalefall” as they feast on the carcass alongside crabs, clams and fish. The microbes produce chemicals that other microbes can put to use. The result is a community whose demographics shift dramatically over time depending on the depth and pressure of the ocean.

Orphan and Goffredi visit these whalefalls two or three times per year, sampling the water, wildlife and sediments to discover if something has changed.

“Almost every time, we find a new species,” Goffredi said. “And that’s just the animals.” The microbes, she added, are guaranteed to produce something that’s never been seen before.

The primary purpose of this two-day expedition is to steer an underwater rover into Monterey Canyon, insert chemical-laced sediment samplers and retrieve specimens from the deep.

The rover is a yellow box the size of a cargo van with robotic arms and an array of boxes and canisters to hold whatever it finds. Ever so slowly, it is lowered through the ship’s heart into the roiling waters below.

“Marine snow,” Orphan says, her face lighted only by the glow from the screens. “Some of it can be actual animals. There are fecal pellets, or mucus that’s been sloughed off. You think about seawater as being this liquid matrix, but it’s really this living, very dense gel.”

One of the rover pilots uses a robotic arm to grab a cylindrical core sampler. He shoves it deep into a spot Orphan chooses, filling it with sediment. Then he uses a second robotic arm to inject fluid into the container.

In a few months, the ship will return and pull the cylinders out of the ground. Then the scientists will analyze the sediment to track the isotopes’ progress through the microbial system. The results will reveal how the microbes eat, grow and share resources with one another.