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Photo courtesy of Edward Laws
UH biological oceanographer David Karl, who was a member
of the team that studied the effects of atmospheric dust on ocean
life, here captivates a kindergarten class at St. Clement's School
with stories about Antarctica, where he does research. "By our
reading of the cards," said Karl, a former high school teacher,
"if you don't get kids by grade four, you've lost them in
terms of getting careers in science."

Research shows
atmospheric dust-life
link in ocean

---

By Helen Altonn
Star-Bulletin

INVESTIGATIONS of waters off Hawaii and Bermuda show major changes are occurring in the North Atlantic Ocean compared with the North Pacific.

The reason: dust.

The North Atlantic is getting more of it than the North Pacific because of natural and man-made impacts, and it's affecting the ingredients needed for life in the ocean.

David Karl, University of Hawaii biological oceanographer, and colleagues reported the findings in a paper published last week in the journal Science.

Their research was conducted at a site about 60 miles north of Oahu, called Station ALOHA, and at a sister site near Bermuda in the North Atlantic.

The Ocean Time-series programs were initiated in 1988 to study ocean and atmospheric systems and look for changes stimulated by natural or human forces.

In looking for variations, the researchers focused on the sea's microbial life.

"Life almost certainly began in the sea and over the past four billion years, selection and evolution has resulted in a very diverse and well adapted assemblage of microorganisms," Karl said.

Despite diversity, he cites a common recipe for life: carbon, nitrogen, phosphorus and sulfur to build new cells, and various trace metals to sustain cell function.

Phosphorus appears to be the most important element to build cells and iron is the key to survival, he said.

The time-series studies revealed "a very substantial depletion of phosphorus -- the staff of life -- in the central North Atlantic Ocean near Bermuda," Karl said.

The researchers found 1 percent less phosphorous in the North Atlantic than at comparable latitudes near Hawaii. They believe iron deposited in the ocean from the atmosphere is responsible.

Karl said the iron stimulates activities of specialized microbes capable of converting a nearly unlimited supply of nitrogen gas that is dissolved in seawater into a biologically useful form.

In doing that, they stimulate the entire oceanic food web to produce more organic matter until phosphorous is nearly exhausted or assimilated, he said.

Dust reaches the Atlantic from the Sahara Desert and dried lakebeds in sub-Saharan Africa, which are increasing because of drought, and altered land and water use practices, Karl said.

"Consequently, both natural and man-made changes are impacting the dust delivery to the North Atlantic and affecting major changes in the rates of food production far downstream," he said.

In the Pacific, the major iron source is dust from western China's deserts, which are shrinking due to improved irrigation and agricultural practices, Karl said.

Also, the Pacific Basin is much larger than the Atlantic, so dust has to be carried greater distances to support food production in Hawaii's waters.

As a result, Karl said, "The North Atlantic is iron-sufficient and phosphorus-starved, and the North Pacific is believed to be iron-controlled."

Working with Karl at Station ALOHA were UH researchers Bob Bidigare and Mike Landry. They have gone to the site once a month since October 1988 to collect data.

Ed Boyle, a Massachusetts Institute of Technology oceanographer, was chief investigator in the North Atlantic. Others on the team were Jinfeng Wu, an expert on iron chemistry and senior author of the paper, and William Sunda, specialist on iron in phytoplankton at the National Oceanic and Atmospheric Administration's Beaufort Laboratory in North Carolina.

In a telephone interview from Snowbird, Utah, where he is attending an ecology meeting, Karl said he, Boyle and colleagues proposed another study several years ago under a new National Science Foundation program on biocomplexity established to examine complex interactions between chemistry, biology, climate and physics.

They received $7.5 million for a five-year program that will begin in the two oceans next year after the new UH SWATH (small waterplane area twin hull) vessel arrives. It is being built in Jacksonville, Fla.

Also, unexpectedly, the NSF gave the Station ALOHA researchers a "special creativity award" of $2 million that they didn't request to continue their investigations.

He said the Atlantic and Pacific oceanographers will continue comparisons between the two oceans to try to understand the ecosystems.