Dennis J. McGillicuddy talks
with ScienceWatch.com and answers a few questions
about this month's Fast Breaking Paper in the field of
Article Title: Eddy/wind interactions stimulate
extraordinary mid-ocean plankton blooms
Year: MAY 18 2007
* Woods Hole Oceanog Inst, Woods Hole, MA 02543 USA.
* Woods Hole Oceanog Inst, Woods Hole, MA 02543 USA.
(addresses have been truncated)
Why do you think your paper is highly
It has been known for some time that episodic eddy-driven upwelling can
fuel biological productivity in the open ocean. We reported new
observations revealing that, although plankton blooms occur in at least two
different kinds of eddies (cyclones and mode-water eddies), the biological
Mode-water eddies can generate extraordinary diatom biomass and primary
production at depth. These blooms are sustained by eddy/wind interactions,
which amplify the eddy-induced upwelling. In contrast, eddy/wind
interactions dampen eddy-induced upwelling in cyclones. The carbon export
inferred from oxygen anomalies in eddy cores is one to three times as much
as annual new production for the region, suggesting these features could
contribute significantly to biogeochemical cycling in the ocean.
Does it describe a new discovery, methodology, or
synthesis of knowledge?
"During our 2005 field season, we
had to contend with three tropical
storms/hurricanes, as the particular eddy we
were studying seemed to be a magnet for storm
activity! Fortunately, we were able to dodge
the storms and get useful samples in nearby
waters, making the most of the precious sea
time allocated to this
I think there is some of all three in this paper. For the most part, this
study relied on established measurement techniques and protocols. However,
the overall methodology was novel by virtue of our integration of satellite
remote sensing and in situ observations for adaptive sampling of
eddy features. This approach allowed us to be "in the right place at the
right time" to sample episodic phenomena, in some ways analogous to the way
hurricane hunters strategically position themselves to make their
The results were extraordinary, insofar as some of the biological and
biogeochemical signals we observed were outside the envelope of all prior
observations in the region. These findings led us to a new understanding of
the mechanisms by which wind forcing interacts with ocean currents to
create upwellings and downwellings of near-surface waters that
significantly impact biological productivity.
Would you summarize the significance of your paper in
New evidence suggests that the currents, fronts, and eddies that comprise
the "internal weather of the sea" could play a vital role in regulating
ocean productivity. Turbulent storms in the interior of the sea can
transport large quantities of nutrients from the deep sea into the well-lit
surface layers, fueling massive profusions of plankton. Because they are so
intermittent, such blooms largely escape detection by traditional
oceanographic sampling techniques.
Fortunately, new methods of synthesizing satellite data and computer models
permit scientists to locate these areas in real time, making it possible to
guide research vessels directly to where such events are taking place. The
ability to effectively observe these highly episodic "oases in the oceanic
desert" is leading to better understanding of their importance in the
functioning of marine ecosystems and biogeochemical cycling.
How did you become involved in this research, and were
there any problems along the way?
This research project was the culmination of several years of planning. It
was a team effort involving six institutions; more than 70 scientists,
postdoctoral fellows, students, and technicians participated in some way.
As with any seagoing field effort, weather is a critical and uncontrollable
factor. During our 2005 field season, we had to contend with three tropical
storms/hurricanes, as the particular eddy we were studying seemed to be a
magnet for storm activity! Fortunately, we were able to dodge the storms
and get useful samples in nearby waters, making the most of the precious
sea time allocated to this project.
Where do you see your research leading in the
Understanding the functioning of marine systems requires an integrated
strategy that includes theory, observation, and modeling. Coupled
interdisciplinary model systems provide a focal point for such synthesis,
in that such models are used to construct space-time continuous
representations of oceanic fields that cannot be achieved through
observations alone. Simulations thus provide a four-dimensional framework
for the analysis of coupled physical-biological-chemical processes that is
not accessible by any other means.
However, in order to make these models truly relevant to the real ocean, it
is absolutely crucial that they be firmly grounded in data. This
synergistic conjoining of observations and models not only provides a
useful methodology for process studies, but also maximizes the utility of
observations and aids in their interpretation.
Do you foresee any social or political implications for
Understanding the controls on biological productivity of the ocean is of
societal importance for two main reasons. First, plankton productivity sets
a first-order constraint on the energy available to sustain oceanic
ecosystems. Effective stewardship of the living marine resources that
mankind uses for food and other needs requires knowledge of how these most
basic aspects of the food web are regulated. Second, when the organic
particles created by plankton sink into the deep ocean, carbon is
effectively removed from the surface ocean. This so-called "biological
pump" plays a key role in partitioning of carbon dioxide between the ocean
Since the industrial revolution, one-third to one-half of the carbon
dioxide released into the atmosphere has gone into the ocean. Whether or
not the ocean will continue to absorb that much carbon dioxide depends in
part on the ocean's biological response to climate change. Thus, plankton
productivity may be a key feedback in the earth's climate system.
Dennis J. McGillicuddy, Jr., Ph.D.
Woods Hole Oceanographic Institution
Woods Hole, MA, USA Web ¦ Web
Keywords: episodic eddy-driven upwelling, biological
productivity, open ocean, plankton blooms, cyclones and mode-water
eddies, diatom biomass, eddy/wind interactions, eddy-induced upwelling,
cyclones, carbon export, oxygen anomalies, mode-water eddies,
biogeochemical cycling in the ocean, satellite remote sensing, ocean
currents, upwellings and downwellings of near-surface waters, carbon
dioxide, the earth's climate system.