Take a look also at the difference in the Y-axes: One only goes up to a 150, but in the inside patch, the scales are dramatically shifted, indicating both that biomass is increased and also that the size spectrum of the community shifts dramatically.

imageIn terms of the geochemical response, I know we've been talking about carbon a lot. You can't really talk about carbon without talking about iron. This slide shows a transect through the fertilized patch. The X axis is is in Greenwich Mean Time, and the data is is from the ship's pumping seawater system. This fluorescence represents chlorophyll or plant biomass, increasing dramatically in the enriched area, and then falling off. Nitrate, on the other hand, was consumed in this area.

There is a significant decrease in CO2 levels in the water. This is the parameter that's thought to have climatic significance.

imageI want to give you a sense of what this actually looked like. I can't give you a sense for what it smelled like or what it felt like, but this is what the Equatorial Pacific normally looks like with bright tropical blue color.


This is what it looked like at about day six. This is the difference between warm, 30-degree Equatorial Pacific, and warm 30-degree, almost coastal Monterey phytoplankton. You could smell this change on board a ship, and it looked like this for miles and miles and miles.

imageSo what did we find? Equatorial systems are limited by iron availability to the phytoplankton. With iron additions, there is essentially a shift in ecosystem structure, which leads to export of organic carbon from the surface water to the deeper water. From some preliminary calculations, using the budgeting of the nitrate deficiency, we estimate that on the order of 1800 tons of carbon may have been removed in about seven days.

So we have questions for the future. Some of these have been answered recently by the SOIREE and by the EisenEX cruises in the Atlantic sector of the Southern Ocean. I want to talk a bit about some of our Southern Ocean cruises with the JGOFS program (Joint Global Ocean Flux Study) into what is the largest mass of high-nitrate, low-chlorophyll water.

imageAs part of the U.S. JGOFS program in the Southern Ocean, we towed this undulating device that flies up and down through the water column, sweeping img of phytoplankton, biomass, chlorophyll and fluorescence, zooplankton, temperature, salinity, and oxygen. By towing this sled for 800 miles, we can make these murals of ocean section. We see that during the springtime, in parts of the Southern Ocean, there's very little biomass in the water column. But during the summertime a significant bloom develops in this peculiar region just south of the convergence zone.

Back to Top
Page | 1 | 2 | 3 | 4 | 5 |

American Society of Limnology & Oceanography - © Copyright 2002
Disclaimer & Directions for Downloading
Site Design Credits