From: Andy Soos, ENN
Published March 20, 2013 04:40 PM
Plankton and CO2
Plankton are any organisms that live in water and are incapable of
swimming against a current. They provide a crucial source of food to
many large aquatic organisms, such as fish and whales. The true base of
the food chain. Though many plankton species are microscopic in size,
plankton includes organisms covering a wide range of sizes, including
large organisms such as jellyfish. Models of carbon dioxide in the
world's oceans need to be revised, according to new work by UC Irvine
and other scientists published online Sunday in Nature Geoscience due to
plankton. Trillions of plankton near the surface of warm waters are far
more carbon-rich than has long been thought, they found. Global marine
temperature fluctuations could mean that tiny Prochlorococcus and other
microbes digest double the carbon previously calculated.
In making their findings, the researchers have upended a decades-old
core principle of marine science known as the Redfield ratio, named for
famed oceanographer Alfred Redfield. He concluded in 1934 that from the
top of the world's oceans to their cool, dark depths, both plankton and
the materials they excrete contain the same ratio (106:16:1) of carbon,
nitrogen and phosphorous.
Plankton inhabit oceans, seas, lakes, ponds. Local abundance varies
horizontally, vertically and seasonally. The primary cause of this
variability is the availability of light.
A secondary variable is nutrient availability. Although large areas of
the tropical and sub-tropical oceans have abundant light, they
experience relatively low primary production because they offer limited
nutrients such as nitrate, phosphate and silicate.
So it is not surprising to find variations in the composition of the
plankton. The new study's authors found dramatically different ratios at
a variety of marine locations. What matters more than depth, they
concluded, is latitude. In particular, the researchers detected far
higher levels of carbon in warm, nutrient-starved areas (195:28:1) near
the equator than in cold, nutrient-rich polar zones (78:13:1).
"The Redfield concept remains a central tenet in ocean biology and
chemistry. However, we clearly show that the nutrient content ratio in
plankton is not constant and thus reject this longstanding central
theory for ocean science," said lead author Adam Martiny, associate
professor of Earth system science and ecology & evolutionary biology at
UC Irvine. "Instead, we show that plankton follow a strong latitudinal
pattern."
He and fellow investigators made seven expeditions to gather big jars of
water from the frigid Bering Sea, the North Atlantic near Denmark, mild
Caribbean waters and elsewhere. They used a sophisticated $1 million
cell sorter aboard the research vessel to analyze samples at the
molecular level. They also compared their data to published results from
18 other marine voyages.
Martiny noted that since Redfield first announced his findings, "there
have been people over time putting out a flag, saying, hey, wait a
minute." But for the most part, Redfield's ratio of constant elements is
a staple of textbooks and research. In recent years, Martiny said, "a
couple of models have suggested otherwise, but they were purely models.
This is really the first time it's been shown with observation. That's
why it's so important."
For further information see
Plankton Rich.
Plankton image via Wikipedia.
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