Then, in a paper that just appeared a few issues ago in the journal
Nature, we discovered novel picoeucaryotic microorganisms in the
marine plankton, and, of course, this leads to the key question,
"are there additional key discoveries yet to be made?"
This reminds me of the old Arlo Guthrie song about the Nixon-Watergate
era. "If he didn't know about that one, then what else don't
he know?" Well, this brief history of oceanic microbes tells
us a little bit about our level of ignorance of biological oceanography.
is it so important to know about microorganisms? Well, it turns
out that microbes have a fundamental role in global ecology. They
control the production and consumption of organic matter, as Dr.
Chisholm just alluded to; they also control oxygen levels, pH and
redox levels in the sea. Most of the chemical reactions in the ocean
are poised by marine microorganisms. They also produce and consume
greenhouse gases, and they make available, or unavailable, various
forms of nitrogen.
let's talk about the ocean's carbon cycle. The carbon cycle is an
intersection between physical and biological processes, between
gases like CO2 and organic matter, both in the dissolved and particulate
We have a large and ever-increasing reservoir of CO2 in the atmosphere.
This reservoir is in equilibrium with the surface ocean under the
control of gas laws and habitat characteristics (e.g., solubilities,
wind speed, etc.). Major circulation processes redistribute inorganic
carbon around the world's oceans.
Intersecting this inorganic, physical system is the organic carbon
system, which I'd like to focus on today, the so-called biological
pump. This complex system begins with the production of organic
matter via the process of photosynthesis, and the removal of the
unused organic matter in the form of dissolved and particulate carbon
into the ocean's interior where it is sequestered for periods ranging
from decades to centuries.