Skip to comments.Algal Blooms Fuel Ocean Food Web
Posted on 04/29/2002 10:34:42 AM PDT by cogitator
Algae Blooms Fuel Ocean Food Web
SANTA BARBARA, California, April 26, 2002 (ENS) - The color of the ocean may yield clues about the relation between marine ecosystems and the climate system, say scientists from the University of California at Santa Barbara (UCSB).
A green ocean is a productive ocean. The light from the sun fuels the bloom of phytoplankton, tiny ocean plants that turn the sea's surface a light green each spring.
"When viewed from space, the north Atlantic spring bloom is among the largest mass greenings observed on the Earth's surface, extending over scales of more than 2,000 kilometers [1,243 miles]," states the article. The blooming moves north at speeds of up to 20 kilometers (12 miles) per day, leaving a green wake in its path.
This production in turn drives ocean food webs, and helps transport carbon dioxide into the deep ocean.
UCSB researcher David Siegel and colleagues analyzed ocean color data from the satellite Sea viewing Wide Field of view Sensor (Sea WiFS) to learn more about the factors regulating the spring bloom of phytoplankton in the north Atlantic Ocean. Their research appears today in the journal "Science."
"The productivity of the ocean is well established," said Siegel. "What we don't know is how it gets recycled, how the food chain works. We're trying to get at these loss processes, which will tell us how the ocean's biological pump works."
The biological pump is the mechanism by which carbon dioxide is transported from the surface ocean into the deep ocean by attaching to sinking particles, such as the remains of phytoplankton that have died off after blooms. Understanding how carbon dioxide, a greenhouse gas, is absorbed by the ocean, and how different mechanisms contribute to this absorption, is a critical factor in understanding global climate change.
From the satellite information, Siegel and colleagues learned that the primary condition needed to start a spring bloom is enough light reaching down into the water column, a condition that occurs when ocean waters turn over or mix in the spring.
"We were able to confirm that a simple model developed many years ago, based on observations in coastal waters can be used to explain the timing of the spring growth period in the entire North Atlantic," said Jim Yoder, a co-author of the paper and division director of ocean sciences at the National Science Foundation.
"We also quantified the role that plankton animals and bacteria play in determining the timing of the phytoplankton bloom and its duration," Yoder added.
Previous research on spring blooms was done at sea with microscopes and other tools. By using satellites, Siegel and Yoder were able to evaluate the process using tens of thousands of data points, rather than just a few.
The satellite ocean color data provides measurements that cover the entire north Atlantic during all seasons and years. Such measurements are a tool for studying natural phytoplankton variability - an important characteristic of marine ecosystems.
The research was funded by the National Science Foundation and the National Aeronautics and Space Administration.
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