Many people would be surprised to learn that the earth’s oceans teem with between
10 to 100 million viruses in every teaspoonful of seawater. That discovery was
made a decade ago by a graduate student in the lab in which UBC microbiologist
and oceanographer Curtis Suttle was doing post-doctoral work.
“The timing of the discovery really focused attention on the fact that micro-organisms
are extremely important,” says Suttle, now an associate professor in the departments
of Earth and Ocean Sciences, Botany, and Microbiology and Immunology.
Two years after he witnessed the groundbreaking discovery by Lita Proctor
in microbial ecologist Jed Fuhrman’s lab at the State University of New York
at Stony Brook, Suttle started his own research into finding out why viruses
exist in such high numbers in the sea and what roles they play in marine and
global ecosystems.
“Lita’s work looked at viruses that infected bacteria in the ocean so I decided
to look at viruses that affect photosynthetic organisms in the ocean,” he says.
Suttle’s research to date has revealed that indeed viruses play a major role
both as destructive disease-causing agents and as part of the control mechanisms
of the seas.
His research into how marine viruses infect and kill phytoplankton — the
tiny photosynthesizing organisms that form the base of the food web in the ocean
— showed that viruses have a tremendous impact on these ecologically important
groups.
While Suttle proved that viruses can reduce the production of organic carbon,
he has also studied how they can aid the release of organic matter into the
oceans. His work revealed that carbon — the common currency of plankton and
all other living things — is not always directly transferred from one organism
to another through consumption. A large amount is released directly into the
sea by bacterioplankton killed by viruses. This released carbon is then incorporated
by other bacteria and lost through respiration.
“As much as 25 per cent of all living carbon in the oceans goes through viruses,”
he says.
As head of the Molecular Marine Microbiology and Virology Lab, Suttle and
his team of a dozen researchers and students are working hard to broaden understanding
of marine viruses.
But while viruses have been mainly thought of as pathogens, Suttle says they
also play an essential part in the normal running of marine ecosystems.
His experiment in selectively removing viruses from seawater showed that instead
of a rise in the growth of the remaining planktonic organisms, the plankton
stopped growing completely. It demonstrated that the living organisms depend
on the nutrients released as other organisms are killed by the viruses, thus
illustrating the vital control mechanism that viruses play in marine ecosystems.
Suttle says the legacy of excellent research by his faculty colleagues —
the Oceanography group celebrated its 50th anniversary this fall — and the
availability of bright and motivated graduate students was a major factor in
his decision to relocate his lab here from the University of Texas.
On top of that, UBC is his alma mater — he completed both his undergraduate
and doctorate degrees here.
“It’s funny, I am actually in the same office as when I was a grad student
here,” he laughs. “So I guess you can say I have come full circle.”
