milky white cloud blooms in the Barents Sea, so vast it can be seen
not the result of some toxic chemical spill or the sinking of a
dairy-filled tanker - it's the handiwork of millions of microscopic
doing what their kind have done for millions of years.
algae, Emiliania huxleyi, somewhat mysteriously produce ultra-thin
scales made of chalk that surround their single-celled bodies.
it's not exactly clear how the scales benefit the algae, scientists
say they provide an important benefit to the rest of the world
build up their chalky armor, E. huxleyi eat up the dissolved carbon
in the water around them. When the phytoplankton grow new shells,
they shed the old ones, which sink to the bottom of the ocean.
more carbon dioxide builds up in the atmosphere and gets absorbed
into the ocean, E. huxleyi and similar types of these calcifying
phytoplankton are there to capture and store it away - just as trees
"inhale" carbon dioxide.
operation is so massive and industrious that an ancient species of
phytoplankton, through a similar process of scale-building and
shedding, gave the famous White Cliffs of Dover in southeastern
England their distinctive color as their shells piled up over tens of
millions of years.
carbon dioxide fuels this undersea industry, it also threatens to
destroy it, according to a study published Friday in Science
calcifying phytoplankton, of which E. huxleyi is the most abundant
species, some extra carbon in the environment means more fuel for
scale-making. But that's only beneficial to a certain point.
humans fill the air with the carbon dioxide and greenhouse gases that
cause global warming, much of that carbon gets dissolved in the
ocean, causing the water to acidify.
called the twin of global
corals and shellfish, whose shells are made of the same stuff as E.
huxleyi's scales, to disintegrate.
more acidic ocean eventually will cause phytoplankton like E. huxleyi
to abandon their calcifying process. As the phytoplankton lose their
appetite for carbon, they leave more of it in the environment. This,
in turn, could worsen the effects of climate change, said Thorsten
Reusch, a marine ecologist at the GEOMAR Helmholtz Centre for Ocean
Research Kiel and senior author of the study.
find out how phytoplankton will adapt to future sea changes, Reusch
and Lothar Schlueter, then a doctoral student, needed to simulate the
ocean conditions of the future.
the lab, the scientists placed identical clones of E. huxleyi in
varying levels of "acidified" oceans, including one that
replicated conditions found today.
the lab, E. huxleyi grow extremely fast, producing a new generation
about once a day. Over four years, the algae copied themselves 2,100
times, essentially allowing the scientists to watch how the species
will evolve under future ocean conditions.
can have the organisms of tomorrow in the lab of today," Reusch
said. "It's like 'Jurassic Park' in reverse."
the first year of the experiment, acidified E. huxleyi reacted by
initially reducing their scale productivity. However, the algae
eventually adapted to the new conditions and took up calcification
in highly acidified oceans, phytoplankton can't produce scales and
maintain their proper body chemistry. Instead of forming scales, they
switch to survival mode. After four years of simulated ocean
acidification, the phytoplankton shut off their scale production.
don't like a more acidic ocean," Reusch said.
the researchers returned the algae to "normal" conditions,
they went right back to work making their sales.
know when to reduce calcification," Reusch said. "They just
switch it off when it's costly, but they switch it back on when the
conditions are normal."
are vitally important to the way oceans - and the world - work.
microscopic algae form the base of the marine food web and are
responsible for producing much of the world's oxygen.
second breath you take comes from their photosynthesis," Reusch
though the study found it's possible to restore phytoplankton's
carbon-cycling ability by returning them to an un-acidified ocean,
such a scenario is "not foreseeable," Reusch said. Even if
we reduce atmospheric carbon
he said, ocean acidification is likely to continue.
have to live with ocean acidification
for hundreds of years," he said.
dynamics of adaptive evolution in a globally important phytoplankton
species to ocean acidification, Science
08 Jul 2016: Vol. 2, no. 7, e1501660, DOI: