Science Results : Daily Update

Daily Update | Current SEA Research

July 5, 2010

By Giora Proskurowski

Today's science update is from Emelia, one of only three non-SEA alums on the boat, and the only volunteer who is not an alumnus. I met Emelia two years ago on the R/V Atlantis on a cruise to the East Pacific Rise with the deep-sea submersible Alvin. As I started developing a microbiological component for this cruise, I immediately thought that Emelia's personality, work ethic, and microbiological skills would be a perfect fit for this trip. Although Emelia is just about to finish up her Ph.D. at UMass Boston, she thankfully agreed to come sailing.

By Emelia DeForce

We have been collecting tiny pieces of plastic over the last several weeks and preparing them for further investigation back in the labs of Tracy Mincer at Woods Hole Oceanographic Institution (WHOI) and Linda Amaral-Zettler at Marine Biological Laboratory (MBL). In the labs – both in Woods Hole, Mass. – we will study the microbes living on the plastic through DNA analysis, microscopy, and growth experiments.

By extracting the DNA present on the plastics found floating at sea, we will be able to use molecular techniques to answer questions about what species of microbes are living on the plastic and also how many of them are living there. We can get an idea of which organisms are abundant and which are rare to help us better understand the microbial community on the surface of the plastic. Questions about whether different types of plastic harbor different microbial communities can be answered.

Studying their DNA sequences can even help us design probes to "fish" out certain species of microbes, allowing us to investigate their metabolisms. Furthermore, the results from the DNA work can be coupled with microscopy for visualization of the microbial community.

Some of the preliminary microscopic work prior to this cruise shows an intricate layer of microorganisms living in a matrix known as a biofilm. So far, it appears the biofilm harbors a diverse group of microbes from prokaryotes to eukaryotes spanning the "Tree of Life." The microbes living on the plastic have created an intricate mesh made of thin hair-like filaments. This mesh may act as a protective measure to protect the microbes from the harsh environment of the open ocean. The probes created from the DNA work will allow us to fluorescently label certain species of microbes that will glow under the microscope, making it easier to identify the structure of the microbial community.

During our time at sea we have collected colonized plastics and placed them in small glass vials with sterile seawater to incubate over a period of time. These experiments will allow us to see the development of the microbial communities as well as to potentially keep them alive until we return to the labs at WHOI and MBL. The sterile seawater excludes microorganisms that are not associated with the plastic allowing those of interest to remain in the vials for metabolic testing at a later date.

The hours of microbial ecology work during our time at sea will help reveal the role microorganisms play in the colonization and potential decomposition of plastics in the Atlantic Ocean. The results from this work will provide data that will be fundamental to further the investigation of the fate of plastics at sea.

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For more from sea, listen to an interview with Chief Scientist Giora Proskurowski on the July 2, 2010 Science Update podcast, produced by AAAS.