Majestic white spires of the Lost City protrude out of a mountain located 800 meters below the Atlantic Ocean. In December of 2000, a team of researchers set out aboard the research vessel Atlantis to explore why a large undersea mountain formed. A volcanic activity revealed rock from Earth's mantle to the ocean at this location a few million years ago. Rock-water reactions known as serpentinization started creating the tall chimneys as these rocks formed to form the mountain on which the Lost City rests. The Lost City's chimneys are one-of-a-kind. The migration of magma under the oceans creates almost all other hydrothermal processes on the seafloor. The famous ‘black smoker' chimneys that result are actually volcanoes, spewing massive clouds of billowing black smoke laden with minerals such as iron sulfides. They are home to a complex species of red and white tube worms, clams, shrimp, and other life forms that depend on the minerals expelled from the Earth's core.
The Lost City's Chimney
The Lost City chimneys, on the other hand, vent transparent fluids. They seem lifeless at first sight. Closer inspection reveals dense deposits of snotty-like fibers resembling white algae dancing about in the seawater clinging to rocks. Biofilms, or slimy communities, are the most abundant life in this ecosystem. Lost City chimney venting fluid is hot, transparent, and full of hydrogen and methane. The fluids in chimneys attain a mean temperature of 100°C and have a pH of about 10. Black smokers, on the other hand, can exceed temperatures of up to 400°C and have a more acidic pH of 2 to 5. The distinctions between the two types of chimneys are due to the various types of rocks under them. The serpentinization reactions will contain hydrogen, methane, and other possible food for microbial life because of the chemical structure of the mantle rocks underneath the Lost City. The Lost City is unlike any other found on Earth, but analogous hydrothermal processes are likely to occur on other planets. Europa, Jupiter's moon, is a good example close to home. We must first determine the boundaries of life on Earth if we are to discover life in space. The Lost City is a perfect metaphor for the kinds of areas where people are looking for life outside Earth. The Lost City gave us a new way to live on Earth, one that didn't rely on sunshine or an active world for electricity, but instead on rock and water. Many concerns about these enigmatic serpentinite-hosted environments, however, remain unanswered.
In the Deepest Oceans
Dr. Deborah Kelly of the University of Washington led early expeditions that established an information base for the Lost City. As a result of this research, it was discovered that as chimneys mature, they experience chemical, geological, and biological changes, as well as a cooling of temperature and a more neutral pH. Early expeditions led by Dr. Deborah Kelly of the University of Washington developed a knowledge base for the Lost City. This study discovered that when chimneys age, they undergo chemical, geological, and biological modifications, as well as a cooling of temperature and a more neutral pH. In particular, a single species dominates the more harsh atmosphere of the chimney interiors, which expands by converting carbon dioxide to methane. Since it was first discovered in this ecosystem, this species is known as the Lost City Methanosarcinales. Geochemists learned from these early expeditions that the system's high pH causes carbon dioxide in the venting fluids to interfere with calcium in the seawater, extracting it from the fluids and posing a conundrum for the microorganisms. The carbon source at the base of the food web of most environments is carbon dioxide; however, there is no detectable volume of carbon dioxide at the Lost City. Microbes in this ecosystem, according to a new theory, rely on formate, a molecule that is basically carbon dioxide with an extra hydrogen atom.
This theory guides my work as an environmental microbiologist in Dr. William Brazelton's laboratory. I deal with DNA sequences extracted from the Lost City's chimney rocks. This DNA may hold the key to understanding how the Lost City microbes use carbon, but sorting through it is a computational nightmare.
