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Over the past twenty years,
researchers have amassed a repository of chlorophyll concentration
data about the land. That measurement is called NDVI, for the
Normalized Difference Vegetation Index. But chlorophyll
concentration measurements regarding the ocean have remained
elusive.
This release from the SeaWiFS
research team marks the first continuous record of surface
chlorophyll concentration in the ocean. The power of these three
years of collected data can be summed up by a single word:
continuity. By taking three years of continuous data as a whole,
experts have been able to map trends and anomalies in the global
circulation of carbon to a degree of detail than has never been done
before. It is a baseline measurement to by which all future
measurements will be compared.
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WATER PLANET: LIVING PLANET
NASA designed SeaWiFS to study
ocean processes. But the mission has surpassed its initial design
goals. By carefully calibrating the sensor, experts have been able to
use SeaWiFS data to monitor life on land, too.
In addition to the release of the first
validated carbon cycle data, the project has noticed an increase in
plant productivity on land in the past three years. This is
interesting because supporting research shows that there hasn’t been
any atypically fast growth on land in that time. Scientists conclude
that the increased productivity is tied to increased rainfall averages
connected to the most recent El Nino phenomena.
As we consider a globe painted in the
color-coded data gathered by SeaWiFS over the last three years, it’s
important to note the relative oxygen production of plant life in the
ocean versus on land. While the ocean doesn’t put out as much oxygen
per square meter as vibrant rainforest, taken as a whole the ocean
does produce roughly the same amount as the Earth’s total land
surface. This is due to the vastly larger area of ocean on the
surface, essentially making up for the discrepancy in square meter
productivity.
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THINK SMALL:
PHYTOPLANKTON AND THE CARBON CYCLE’S
FOUNDATION
The ocean is not
simply empty space filled with water and the occasional fish. It
teems with life of myriad varieties, and pulses like a heartbeat
with the changing seasons. That rhythm plays a fundamental role in
regulating the health of all life on
Earth. But while the
familiar forms of stingrays and blue whales and kelp beds and sea
urchins are the most easily recognizable, in terms of the biosphere,
the action starts in a different population.
It’s called
phytoplankton. They’re tiny, single celled plant organisms that
form the root of the oceanic food chain. Little more than bits of
greenish implications of life, immense and uncountable clouds of
these plants appear like floating carbon signatures around the
globe, offering evidence about the planet’s health for those who
can read the signs.
The word
"phytoplankton" comes from the Greek. Phyto-, meaning
"plant", and –plankton meaning "free
floating". The most common species of phytoplankton is a tiny
specimen called prochlorococcus. Each individual in a colony of
prochlorococcus measures less than one micron across. In fact, it’s
largely due to the extremely small size of this humble life form
that its existence wasn’t even known until the middle of the
1980s. The same goes for a sibling species of phytoplankton called
synococcus. Although less common than prochlorococcus and slightly
larger, by itself it composes one of the most populous
photosynthetic life forms on the Earth.
For years,
researchers have only been able to study phytoplankton in discrete
areas and synthesize a variety of suppositions about how it
interacts with the natural world. But a global look at these humble
plants has not been possible.
Until now.
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SPRING BLOOM in the
NORTH ATLANTIC
The annual bloom of
phytoplankton in the North Atlantic is one of the biggest regular
blooms in the world. As seen here, the area covered by the bloom
is larger than the territory covered by the Amazon rainforest in
South America. In the open waters of North Atlantic, it’s
believed that lots of carbon initially taken up by phytoplankton
ultimately settles to the ocean floor, as the region is not
densely populated by zooplankyton, the next logical rung on the
food chain. Although still inconclusive, studies of this area
suggest strong evidentiary clues as to the process of carbon
uptake and long duration carbon sequestration.
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WESTERN CENTRAL AMERICA
Along the West Coast of
Central America we see extraordinary levels of phytoplankton
growth, due largely to cold water upwellings along the eastern
basin of the Pacific Ocean. This area rich in life supports a
healthy and vibrant diversity of species, each with unique
strategies for survival, but all ultimately dependent on the
first link in the food chain. In human terms this has direct
relevance to fishermen in the region, as the area is world
famous for its significant tuna stocks.
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EQUATORIAL ATLANTIC
– RIVER OUTLETS SUPPORT LIFE
Deep ocean waters are
not the only sources of nutrients for phytoplankton. The
mouths of rivers often wash tons of nutrient rich water into
the sea, providing abundant resources for all sorts of life.
Much of the nutrients that wash
downstream are themselves functions of the carbon cycle as
played out on land. Decomposing plant and animal matter that
might have otherwise been sequestered on land can find their
way into rivers and streams, feeding into the ocean.
South America presents two
excellent examples of river outlets where phytoplankton tend
to thrive. Along the northern part of the continent the mouth
of the Orinoco River opens into the Caribbean. Along the
Eastern side of South America, the mighty Amazon exits its
thousand mile journey. At the end of each, notice the bright
red tails waving against the largely blue-green background of
surrounding Atlantic ocean. That’s the signature of intense
photosynthesis happening—billions of phytoplankton making
their home in those currents, feeding off carbon saturated
foodstuffs and turning sunlight into energy for life.
Also captured in this frame is
a strong signal of phytoplankton growth coming off the western
coast of Africa.
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WESTERN AFRICA
Along the
western coast
of Africa, intense phytoplankton blooms wave back and forth in
Atlantic currents like fern fronds in a breeze. These gigantic
fields of phytoplankton are the products of several factors,
including coastal cold water upwellings and nutrient rich
outflows from central African rivers. The middle parts of the
African continent support extraordinarily dense networks of
life, and the natural runoff from the region has a nourishing
effect on life off shore.
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A SPLASH OF COLOR IN THE
PACIFIC
The bloom associated
with the 1997 to 1998 El Nino to La Nina transition event
splashed across the Pacific Ocean like pigment thrown across
empty canvas. Jetting from west to east, the explosive, yet
short lived growth spurt there coincided with significant
upwellings of cold water corresponding with the onset of La
Nina. During the powerful 1997 El Nino event, SeaWiFS recorded
little or no significant growth of phytoplankton in the
equatorial Pacific.
Although this visualizations
features an intense bloom in the Pacific, it’s interesting
to note that the El Nino/La Nina phenomena as its cause also
contributed to simultaneous decreases in phytoplankton growth
in the western Pacific and large increases in growth just east
of Argentina.
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