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Latest Expedition Journal

October 31:  Day 29

Posted by Gregory Boyd

Plastisphere:  microbes that live on plastic

My name is Gregory D. Boyd and I am a research assistant at Sea Education Association. For the past three years I’ve been sailing as an assistant scientist aboard the Robert C. Seamans and have enjoyed all of the experiences it has offered. During this time, the Pacific Ocean has become a very important part of my life, it is my home.

On the ship, I’ve spent countless hours interacting with people, micro- and macro-fauna, numerous amounts of data, and observing the deep blue that surrounds me.  Inconspicuously, plastic was present; collecting in windrows, circling the gyre, and hiding below the vast surface of the water as well as creating a refuge for adaptive organisms.

I was able to see what this material was doing to the life existing in this place I call home. From dead albatross chicks at National Marine Sanctuaries, to each neuston tow being filled with zooplankton, and zooplankton-sized plastic marine debris, I knew that this pollution needed further investigation. On the other hand, I saw organisms thriving on the plastic like gooseneck barnacles, algae, and crabs. In hindsight, this was pushing me to better understand the role that plastics play in oceanic ecosystems.

Given my experience with SEA and my undergraduate studies in microbial production of biodegradable plastics, I decided to spend the next three years of my life researching oceanic microbes as a part of a team of four scientists based in Woods Hole, Massachusetts. I work with Drs. Erik Zettler, Linda Amaral-Zettler, and Tracy Mincer at Sea Education Association, Marine Biological Laboratory, and Woods Hole Oceanographic Institution, respectively. The overarching goal of this study is to look at the ecology of microorganisms in seawater as well as on natural and man-made substrates.

On this expedition, I am sampling plastic from dip nets and neuston tows, as well as seawater from the surface and at depth (550 m) using a hydrocast. The seawater and plastic pieces are preserved for nucleic acids in order to find out more about the diversity of microorganisms living on the plastic pieces, known as metagenomics, and their metabolic functions, known as metatranscriptomics.  We will also preserve samples for high-resolution microscopy of the microbial communities on the surface of the plastic. This will allow us to visualize what are known as biofilms, or mats of microbial life that grow on the plastics.

One hypothesis we have is that microorganisms are bioluminescing on plastic.  To test this, I am using the plastic samples to culture bacterial isolates, then using a light-reading luminometer instrument to detect the bioluminescence.  I have been able to detect light emission on plastic pieces from every neuston tow.

While the days are long and the work is constant, I go to sleep at night feeling good about my research, and the search for answers to my questions outweighs the tedious repetition of collecting samples.  As the 1962 Nobel laureate Max Perutz declared, “The glaring light of certain knowledge is dull, and one feels most exhilarated by the twilight and expectancy of dawn.”