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Alex Bochdansky, ODU Oceanographer, Wins $540,000 NSF Grant for Study of Deep-Sea Microbes

Old Dominion University oceanographer Alex Bochdansky has received a $540,000 grant from the National Science Foundation (NSF) for a three-year study of microbes that live in the deep oceans and how these tiny creatures may play a role in the oceans' reaction to climate change.

Eukaryotic microbes-also called protists-of the deep-sea water column, most of which are flagellates that feed on bacteria, are important to the study of the carbon cycle. But they have resisted study because they live so far below the surface, and because their activities and very existence may be severely impacted if they are hauled up three or four miles onto a research vessel.

To counter this, Bochdansky and his colleagues at the Royal Netherlands Institute of Sea Research, have designed and built a pressure culture system that allows them to incubate deep-sea samples and then monitor the microbes at the same pressure and temperature that they encounter in nature. Bochdansky said a seed grant of $50,000 from NSF in 2005 enabled the development of the culture chambers and helped in the formulation of the hypotheses that will be tested in the three-year study.

"Our main hypothesis is that the abundance and taxonomic composition of protists serve as sensitive indicators of the strength and type-particulate or dissolved-of input of organic carbon into the deep ocean system," said the ODU assistant professor of ocean, earth and atmospheric sciences.

The oceans sequester large amounts of carbon that otherwise might be the atmospheric carbon dioxide that is a major constituent of greenhouse gases. For example, phytoplankton and other organisms on the ocean surface absorb carbon dioxide as they grow. Death and decay of this organic growth results in carbon sinking into the deep ocean. Decay is facilitated by bacteria, and the bacteria may be consumed by protists. So Bochdansky and his colleagues at the Netherlands institute believe that the distribution and ecology of the protists serve as indicators of how much carbon is present in these vast, dark zones.

Research already conducted by Bochdansky suggests that protists in the deep are concentrated on organic particles that sink from the surface. "If this is the case, the abundance of protists in the deep seas may be a sensitive indicator of particle flux, or in more general terms, of the input of organic material from the surface, which may include biodegradable dissolved organic matter," he said.

One of the interesting questions he will try to answer in the next few years is whether there are protists in the deep sea that remain dormant for long periods of time and become actively alive when sinking particles become available. He also will investigate whether there are ubiquitous protists near the surface that may sink with particles and become competitive when they have sunk into a deep-sea habitat where the temperatures are sufficiently low and the pressure sufficiently high to trigger their activity.

Bochdansky's project has been endorsed by the international Integrated Marine Biochemistry and Ecosystem Research (IMBER) organization. Data he develops will be shared via the national ocean carbon and biogeochemistry data repository at Woods Hole Oceanographic Institute in Massachusetts.

The ODU scientist said the research conducted under the NSF grant requires an interdisciplinary approach combining physical, chemical and biological oceanography together with ocean engineering. "It would not be possible without recent developments in molecular techniques for the identification of particular organisms and groups of organisms," he explained.

An educational component of the project will be the contributions it will make toward a permanent exhibit on the role of marine microbes-titled "Invisible World-The Realm of Microbial Oceanography-planned for the Nauticus maritime museum and interpretative center in Norfolk.

This article was posted on: July 22, 2008

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