In 1977 a team of geologists from Woods Hole Oceanographic Institution (WHOI) took the manned submersible Alvin to the Galápagos Rift region off the coast of Ecuador. There lies a divergent boundary where the Nazca and Cocos plates separate at the speed fingernails grow, about two inches per year. Studies of the region indicated that heat was cycling along this east-west rift, but the seafloor process remained undescribed. The 1977 expedition, led by Robert Ballard, Ph.D., made an important discovery that would transform our understanding of how life functions on Earth.
Ballard and his team discovered an underwater Yellowstone — a highly geologically active area of lava flows, fissures, vents and chimneys. Towering hydrothermal vents stood as the backdrop for a realm of life no one had ever encountered: towering tubeworms, massive clams, bearded mussels and ghostly white crabs. Peering out of Alvin‘s tiny portholes, the three-man team sat awestruck by the oasis of life they found flourishing — entirely without connection to the sun’s energy.
The tall chimneys grew, spewing vent fluids as hot as 650°F into the frigid surrounding seawater and depositing layer upon layer of dissolved zinc, copper, lead and iron. Billowing from these chimneys like factory exhaust, black vent fluids fed the community of creatures that clamored for Goldilocks real estate — near enough to feed from the flow but not so close as to be scalded.
Until 1977, all food chains and all life were thought to rely on solar energy and photosynthesis. The deep ocean was assumed to be a wasteland where sparse populations of deep-sea creatures looked upward for a meal of meager particles that rained down from the sunny shallows. But deep in the dark ocean, Ballard and his team had discovered organisms that sustained themselves completely with chemicals from within the Earth’s crust. The fact that organisms could harness the energy of chemical bonds, a process called chemosynthesis, dramatically increased the number of habitats capable of carrying life — on Earth and beyond.
Fast forward nearly four decades to 2015. Although technology has made the seemingly impossible accessible and even commonplace, bewilderingly, 90 percent of the world’s oceans remain unexplored. Floating on the open sea two miles above the Galápagos Rift is the 211-foot exploration vessel (E/V) Nautilus. In a darkened control room on its highest deck, a team of engineers, scientists, educators, technologists and students stare captivated into the glow of wall-to-wall video monitors. Each screen is a window onto the crushing and coal-black world being explored by Hercules and Argus, the team’s remotely operated vehicles (ROVs). Linked to the ship by fiber-optic cables and linked to the entire world via live satellite broadcast, these robots are humanity’s eyes on never-before-seen places.
Weighing more than 6,000 pounds and roughly the size of a car, Hercules is loaded with sensors and sampling tools, dexterous manipulator arms and cameras aimed in eight directions. In a decade of exploration, Hercules and Argus have sampled and surveyed deep-sea corals, ancient shipwrecks, underwater volcanoes, seafloor trenches and war history in the Mediterranean, Black and Aegean seas, the Gulf of Mexico and throughout the Caribbean. The goal of the 2015 expedition to the Galápagos Rift is to better understand how hydrothermal vent systems age and change. The voyage also represents a special homecoming. As Ballard directed the team from the Nautilus control center, he laid his eyes on the site of his most important discovery for the first time in nearly four decades.
When WHOI scientists visited the rift region in 2002, the original 1977 vent discovery site was nowhere to be found. Thick lava flows of glassy black blanketed the seafloor in all directions. All evidence of the towering tubeworm communities had been wiped clean, paved over by geological forces. During that expedition, the WHOI group carefully mapped and marked a new venting site named Rosebud. Researchers placed site markers and sampled a rich chemosynthetic community, advancing deep-sea science. When Hercules shone its lights on Rosebud a decade later, only collapsing lava domes, shattered columns and pillowed rock flows could be seen. The shiny basalt glistening in Argus‘ lights and the occasional dead clam told the story of a violent geologic upheaval that had wiped out the ecosystem.
In 2011 the Okeanos Explorer, a collaborating ship from the National Oceanic and Atmospheric Administration (NOAA), found a low-temperature diffuse vent field with nascent life present along the rift. NOAA named the site Tempus Fugit. In this year’s mission, eager to determine how Tempus Fugit had matured in four years, Nautilus deployed its robots. Teams in the control center, collaborating scientists onshore, future explorers in classrooms and public audiences in museums nationwide sat glued to their screens as Hercules inched eastward along the Galápagos Rift.
s the ROV neared the seafloor and a faint white glow appeared at the perimeter of the camera’s view, Ballard’s voice called out from the control center, “We’ve got ’em!” The whole team leaned closer to their screens. From the darkness emerged the white stalks of the iconic tubeworms, Riftia sp., jumbled in stacks like a crumbling pipe organ. Three-foot worms concealed in 10-foot tubes stretched their feathery crimson plumes into the vent flow. The tubes rose like cathedrals all around venting flows. Football-sized clams and mussels spilled out of lava cracks and fissures. Hot water shimmered across the seafloor, blurring the camera’s views of creatures basking in a nutrient soup rising from deep within the Earth. Less than five years had elapsed since ROVs recorded a nearly barren seafloor at this precise location. Data loggers in the control center captured images furiously as surveys identified a community of crabs, octopods, sea cucumbers and vent fish.
The moment of discovery on Nautilus was electric, giddy and ephemeral, and that same thrill was shared with armchair explorers gazing on through smartphones and laptops around the world.
Scientists now support the hypothesis that Galápagos vent communities are overturned on decadal timescales rather than at the millennial pace of many geologic processes. Studying creatures that thrive in this alien world reveals special adaptations for the boom-and-bust unpredictability of living off vent fluids. Riftia worms have no digestive tract; that organ system atrophies after juveniles settle near a vent site to allow more body space for internal chemosynthetic bacteria that harness the hydrothermal buffet flowing past. Almost all organisms in this environment broadcast spawn their larvae into ocean currents, hedging their evolutionary bets that offspring will land near another flow if the parents’ vent fizzles out.
Future exploration of the seafloor will continue to unveil new answers and new questions about the flexibility of this environment and life itself. As pilots guided the robots (and a rapt global audience) through the deep-sea ecosystem, Ballard cheered for the beautiful communities and remarked, “They won’t be here for long. All the wonderful vent sites we discovered in ’77, ’79 and 2001 have been completely destroyed by fresh lava. You’re living on borrowed time when you’re living at the boundary of creation.”
Explore More
Check out this “Giant Black Smoker Hydrothermal Vent” the E/V Nautilus team discovered in the Galápagos Rift region.
© Alert Diver — Q4 Fall 2015