UH’s David Karl delves into the ocean’s mysteries
Oceanographer David Karl
Just when oceanographers thought they had a handle on marine life, discovery of new microorganisms and metabolic systems sent them back to the field and the lab to rework models of the ocean’s ecosystem. Among them is David Karl, an internationally known oceanographer with Mānoa’s School of Ocean and Earth Science and Technology.
The $40-million man (a tally of his research grants) has published dozens of articles and participated in 100 cruises and dives that encompass most of the world’s oceans.
Karl attributes the new findings to several factors: the HOT (Hawaiʻi Ocean Time-series) Program, focusing on carbon cycling, climate changes and marine life; advances in technology and molecular biology and sheer luck. "Some of these discoveries were made by accident, because of ignorance of things we never even thought about," he explains.
Microbes come of age
The study of microorganisms has greatly evolved since Dutch toolmaker Antonie van Leeuwenhoek invented the first microscope and used it to observe what he called "little animals" in 1670. Still, marine biologists continue to be surprised by how little they still know about these infinitesimal sea creatures.
Since the establishment of HOT in 1988, scientists have found two microorganisms that have changed the way they think about the ocean’s ecosystem. One is a tiny cell called Prochlorococcus, a form of plant life that produces oxygen and consumes carbon dioxide. The other is Archaea, a type of microbe that was once thought to live only in extreme environments-hot thermal vents and salt ponds. Both organisms are found to grow in abundance in the ocean.
Calling Karl "one of the leading figures in oceanography," Woods Hole Oceanographic Institution officials presented him with its highest honor in 2004. The Henry Bryant Bigelow Award in Oceanography has been awarded just 13 times since it was established in 1960. "Karl’s work and vision have influenced the directions and perspectives of several disciplines," including studies of climate change, microbial biology, ocean engineering and oceanography in general, said Woods Hole Director Robert B. Gagosian.
"We didn’t even know Prochlorococcus existed until 1988," says Karl. "So how could we possibly put together a conceptual model of the food web, of the energy flow, of the carbon flow when we didn't even know about the most abundant form of plant life on the planet?"
To make matters even more exciting, marine scientists recently found that certain ocean bacteria make a protein that allows them to absorb light, not unlike the protein in our eyes. "In the past we thought that the only organisms that used light energy were plants," Karl says. "Now, we may have a new metabolic pathway to supplement photosynthesis. The open ocean, it turns out, is a huge solar collector!"
The fact that these microorganisms are abundant and can process light opens a whole new world of marine microbiology with impact on the environment, marine industries and medicine. "You could find an organism with a unique composition that is anti-cancerous." While the human genome is made of 30,000 genes, the bacterial genome is estimated to have a million times more, so there’s more diversity, he points out.
Several awards, most recently the Woods Hole Oceanography Institution's prestigious Henry Bryant Bigelow medal in oceanography, hang in Karl’s corner office, which overlooks Diamond Head. "I’m humbled by this," he says, referring to the recent honors. "The award does not make the scientist’s career; it’s the legacy and knowledge you leave behind that’s important."
That’s why he’d like to transform a $3.85 million grant, part of the 2004 Gordon and Betty Moore Foundation Investigator in Marine Science award, into the first UH Center for Microbial Oceanography. Toward this legacy, Karl and a team that includes three other Moore award recipients submitted a 10-year, $40 million proposal to the National Science Foundation. If funded, the center is expected to begin research operations and student training by July 2005.
Karl also looks forward to the day when he can turn his project on global carbon cycling over to a "younger generation of scientists."
The carbon dioxide conundrum
For the last 16 years Karl has studied the global carbon cycle and its impact on the ocean. Data collected at HOT’s Station ALOHA, 60 miles north of Oʻahu, indicate that as carbon dioxide in the atmosphere goes up (adding to the greenhouse effect) so does it go up in the ocean. Scientists predict that in three to five years the ocean "won’t take it anymore."
Short of reducing the use of fossil fuels, scientists have proposed three alternatives for disposing of CO2-trapping it in the atmosphere, turning it into liquid and dumping it in the ocean or burying it in the ground where oil has been pumped out.
Another option involves adding nutrients to the ocean to stimulate the growth of planktons. The idea is that if you stimulate the metabolism of these microorganisms, they will grow, take up carbon dioxide and eventually sink to the bottom of the ocean. "Conceptually this would work," Karl says, "but to do something like this is pretty scary, because up until 20 years ago we didn’t even know who the dominant plant plankton were."
The lure of the ocean
Karl’s interest in the ocean began early in life. His mother, a Cheektowaga, N.Y., librarian, brought home books about the ocean, including Jacques Cousteau’s classics. At 17, he saw the ocean for the first time. "In that moment I changed my plans (of becoming a wildlife biologist) and decided to become an oceanographer." He majored in biology at University College at Buffalo, N.Y., and received an MS in biological oceanography from Florida State University followed by a PhD in oceanography from University of California San Diego in 1978, a year he calls a benchmark in his life.
During an expedition to the Galapagos Rift, he and colleagues discovered strange, worm-like creatures living in thermalvents that were able to survive because of local bacterial based production. "I was one of the first people to see these giant tube worms and say, ʻGee this is weird, why are these things on the bottom of the ocean?’"
The year was also marked by tragedy. A newly hired assistant professor, Karl was to rendezvous with colleagues on the Big Island. The research vessel Holo Holo "was too small, and I couldn’t go," he says. The ship never made it to port. Among the 10 people lost were three UH scientists. "It was a major setback for our program here and in the nation."
Karl was involved in reestablishing a campus memorial garden honoring his fallen comrades, and he has created a CD on the history of oceanographic research at UH. He has also worked with Boy Scouts and supported school science programs, a continuation of community service that began in college, when he volunteered to teach mentally handicapped children and later prison inmates. For the past decade, he has helped manage the population of abandoned and feral cats on the Mānoa campus through approved trap-neuter-release procedures.
"Things have come full circle," says Karl. "I have a strong commitment to give back to the public and to education."
At 55, having spent most of his life in and out of the ocean, Karl is ready to explore firmer ground on his new Harley Davidson. "I’ve been riding motorcycles for 40 years; it’s the only continuity in my life. I expect to be riding as long as I can so that I can take one or more cross country trips to see what I have missed so far."