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![]() Physical
and biological oceanographers led by FSU Professor
William Dewar put the yearly amount of chemical power stored by
phytoplankton
in the form of new organic matter at roughly 63 terawatts, and that's a
lot of
juice: Just one terawatt equals a trillion watts. In 2001, humans
collectively
consumed a comparatively measly 13.5 terawatts. What's
more, their study found that the marine biosphere
––
the chain of sea life anchored by phytoplankton ––
invests around one percent
(1 terawatt) of its chemical power fortune in mechanical energy, which
is manifested
in the swimming motions of hungry ocean swimmers ranging from whales
and fish
to shrimp and krill. Those swimming motions mix the water much as cream
is
stirred into coffee by swiping a spoon through it. And
the sum of all that phytoplankton-fueled stirring may
equal climate control. "By
interpreting existing data in a different way, we
have predicted theoretically that the amount of mixing caused by ocean
swimmers
is comparable to the deep ocean mixing caused by the wind blowing on
the ocean
surface and the effects of the tides," Dewar said. In
fact, he explained, biosphere mixing appears to provide
about one third the power required to bring the deep, cold waters of
the world
ocean to the surface, which in turn completes the ocean's conveyor belt
circulation
critical to the global climate system. Findings
from the FSU-led study ("Does the marine
biosphere mix the ocean?") will appear in the forthcoming issue of the
Journal of Marine Research, adding the role of major power broker to
phytoplankton's already impressive credentials. Scientists
for some time have known that the highly
sensitive plants act as reliable signals of environmental changes at or
near
the ocean surface through sudden declines or rapid growth
–– and they have
suspected that phytoplankton affect as well as reflect climate change
when
large, sustained plant populations gulp carbon dioxide from the
atmosphere
during grand-scale photosynthesis. But
along with the new calculations that point to the marine
biosphere's bigger-than-expected role in ocean mixing and climate
control,
Dewar and his colleagues also suggest that human and environmental
decimation
of whale and big fish populations may have had a measurable impact on
the total
bio-mixing occurring in the world's oceans.
http://www.fsu.edu/ |