Why do you think your paper is highly cited?

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 responses differ.

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?

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 measurements.

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 layman's terms?

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 future?

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 your research?

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 and atmosphere.

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
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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.