In November 2006, Craig McClain sailed into the Pacific Ocean, threw 36 logs overboard, and created several new worlds.
When wood sinks to the bottom of the ocean, whether from shipwrecks, uprooted trees, or keen scientists, it is soon colonised by waves of life. Clam-like creatures called Xylophaga chisel through the wood with their own shells and feed off the liberated splinters. Small crustaceans and predatory worms squirm through the wood. Large squat lobsters sit on the surface, tearing strips off the bark with spoon-shaped claws.
Most of these animals have special adaptations (and microbes) that allow them to digest wood, and they’re only found on woodfalls. McClain estimates that around 90 percent of these species live nowhere else in the ocean. They’re marine creatures that live only on land plants!
I first wrote about woodfalls and their weird inhabitants last year, and I was struck by how little we know about these habitats. Studying the deep ocean is already quite tough; studying woodfalls is especially so. They are temporary ecosystems that appear very suddenly, only to be consumed and decomposed over a few years. They’re a network of worlds that blink in and out of existence across the ocean floor.
To really understand woodfalls, McClain had to create them. Together with James Barry at the Monterey Bay Aquarium Research Institute, he sank 36 acacia logs to the bottom of Monterey Bay in California, in a site affectionately known as Deadwood.
The logs ranged in weight from just a few pounds to around 45 pounds. McClain wrapped each one in mesh laundry bags, lowered them 3 kilometres down onto the ocean floor with a “benthic elevator” (read: a fancy shopping trolley with weights and floats), and scattered them using a remotely-operated vehicle, or ROV (read: underwater robot assistant). Five years later, they collected half the logs.