Was Grandma a Hyperthermophile?
by Peter Tyson
July 15, 1998
Yesterday a low-pressure zone swept in, bringing 30-knot winds, ten-foot seas, and
ROPOS operations to a screeching halt. It
was as if Poseidon, reading exhaustion in the faces of the scientific party after
a successful week of retrieving chimneys, suddenly declared, "Whew, let's take a
break." With the R/V Thomas G. Thompson groaning through stomach-turning pitches,
many retreated shakily to their rooms. The main lab, library, and ROPOS room,
all usually buzzing with activity, were silent, and the half-empty mess at meal-time
revealed that a few of us were a tad under the weather.
By this morning, the seas had calmed, and people began to appear in the passageways again.
While we waited for ROPOS to get to the seafloor, I took the opportunity to catch up with
the biologists, who are studying the bizarre life forms living in and around black smoker
chimneys in search of clues as to how life began on Earth. You haven't heard much about
the biologists, because the focus of the first fortnight was on the engineers and geologists
preparing and collecting the chimneys. But they've been here all along, silently going about
their work and patiently waiting for the next "bio dive."
One is taking place right now, as I write. It is led by Jozee Sarrazin, a vibrant, French-speaking
post-doc at the Woods Hole Oceanographic Institution, and Istvan Urcuyo, a gregarious,
Nicaraguan-born graduate student at Pennsylvania State University. They are collaborating on a
project to minutely characterize the community of life that lives on a single sulfide chimney.
While biologists intimately know the denizens and workings of tiny patches of rain forest and
coral reef, they have conducted few in-depth studies of this kind on hydrothermal vent habitats.
Such communities were only discovered 20 years ago, and the environment they inhabit is extremely
difficult to work in, so many unknowns remain. For example, Urcuyo says that of the more than 300
species of vent life discovered so far, biologists can follow the life cycle of only about three or
Jozee Sarrazin and Istvan Urcuyo examine tubeworms.
Urcuyo and Sarrazin are working hard to fill such gaps in our understanding. In previous work
on the Juan de Fuca Ridge, Sarrazin characterized six different types of biological communities
on sulfide chimneys. They range from Community 1, distinguished by sulfide worms (Paralvinella
sulfincola) living on newly formed chimneys in water reaching 104°F, to Community 6, a senescent
type dominated by dead or dying tubeworms (Ridgeia piscesae) in low-temperature water. Sarrazin's
goal is to determine what factors—including temperature, chemical conditions, substrate type,
and degree of vent flow—control the development of those communities.
Urcuyo is working with her to define, in addition to the overall biomass, the composition, distribution,
and abundance of vent animals on selected chimneys. On a ROPOS dive two days ago that he and
Sarrazin directed, Urcuyo had the pilot on duty scoop a sample off the biologically bristling
chimney Gwenen using a device called the Chimney Master. Like a vacuum-cleaner bag with fingers,
the Chimney Master grabs a known surface area of material and delivers it to ROPOS' biobox.
Later, in the main lab, a number of us chipped in to help Urcuyo and Sarrazin sort the creatures
by species. The sample was from a high-flow Community 5, which is dominated by R. piscesae tubeworms
living in medium-high temperature water. The tubeworms were there in abundance, along with tiny brown
limpets, scale worms, and several species of polychaete worms. There was also a single sea spider and
perhaps a thousand snails of the wonderfully named species Depressigyra globulus.
Meanwhile, Jon Kaye, a graduate student at the University of Washington, told me about the microbial
life he and his advisor John Baross are focusing on. After each of the four chimneys we collected was
lifted onto the deck of the CCGS John P Tully, Kaye and Baross cored them from edge to center. They're
hoping to find out what species live where within different types of chimneys, and what their
relationship is with the geology. For example, do some microbes prefer living on silica while
others go for anhydrite?
When the Tully departed, Kaye joined us here on the Thompson to continue his search for microbes
that live in high-temperature, high-salt-content conditions. No one had ever seen these before,
but already Kaye thinks he has cultured some in his broth tubes. Pulled up from the deep sea,
these microscopic creatures have grown in his incubator at temperatures reaching185°F—hence
their technical name, hyperthermophiles. Will they replicate? Do they prefer or even require super
salinity? The latter would prove they were spewed out from some subsurface community that has those
conditions. Otherwise where did they come from?
"It's all based on Darwinian evolutionary theory, that they exist for a reason," said Kaye, a lithe,
rust-haired man in his early 20s.
"And what might that reason be?" I asked. "Why would anything willingly opt for hyper salinity?"
"Well, maybe they began there and later adapted to live outside of vents. Perhaps we're all descended
from high-salt-tolerant hyperthermophiles."
Such talk has been floating about this ship since we left port. I'd better listen in while I can,
for the word's out that another low-pressure system is on the way, with even higher winds predicted.
The ROPOS dive now underway may be our last before we begin our 18-hour sail back to Seattle tomorrow night.