August 21, 2014

Scientists Discover Thriving Colonies of Microbes in Ocean ‘Plastisphere’

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FOR IMMEDIATE RELEASE: June 28, 2013
Contact: Diana Kenney, Marine Biological Laboratory
508-289-7139; dkenney@mbl.edu, or
WHOI Media Relations Office
508-289-3340; whoi@media.edu

 

WOODS HOLE, Mass.–Scientists have discovered a diverse multitude of microbes colonizing and thriving on flecks of plastic that have polluted the oceans—a vast new human-made flotilla of microbial communities that they have dubbed the “plastisphere.”

In a study recently published online in Environmental Science & Technology, the scientists say the plastisphere represents a novel ecological habitat in the ocean and raises a host of questions: How will it change environmental conditions for marine microbes, favoring some that compete with others? How will it change the overall ocean ecosystem and affect larger organisms? How will it change where microbes, including pathogens, will be transported in the ocean?

The collaborative team of scientists—Erik Zettler from Sea Education Association (SEA), Tracy Mincer from Woods Hole Oceanographic Institution (WHOI), and Linda Amaral-Zettler from the Marine Biological Laboratory (MBL), all in Woods Hole, Mass.—analyzed marine plastic debris that was skimmed with fine-scale nets from the sea surface at several locations in the North Atlantic Ocean during SEA research cruises. Most were millimeter-sized fragments.

Assorted plastic debris collected from the ocean. Credit: Erik Zettler, Sea Education Association

Assorted plastic debris collected from the ocean. Credit: Erik Zettler, Sea Education Association.

“We’re not just interested in who’s there. We’re interested in their function, how they’re functioning in this ecosystem, how they’re altering this ecosystem, and what’s the ultimate fate of these particles in the ocean,” says Amaral-Zettler. “Are they sinking to the bottom of the ocean? Are they being ingested? If they’re being ingested, what impact does that have?”

Using scanning electron microscopy and gene sequencing techniques, they found at least 1000 different types of bacterial cells on the plastic samples, including many individual species yet to be identified. They included plants, algae, and bacteria that manufacture their own food (autotrophs), animals and bacteria that feed on them (heterotrophs), predators that feed on these, and other organisms that establish synergistic relationships (symbionts). These complex communities exist on plastic bits hardly bigger than the head of a pin, and they have arisen with the explosion of plastics in the oceans in the last 60 years.

“The organisms inhabiting the plastisphere were different from those in surrounding seawater, indicating that plastic debris acts as artificial ‘microbial reefs,” says Mincer. “They supply a place that selects for and supports distinct microbes to settle and succeed.”

Suctorian ciliate covered with symbiotic bacteria, along with diatoms, and filaments on weathered and cracked microplastic debris. Credit: Erik Zettler, Sea Education Association

Suctorian ciliate covered with symbiotic bacteria, along with diatoms, and filaments on weathered and cracked microplastic debris. Credit: Erik Zettler, Sea Education Association

These communities are likely different from those that settle on naturally occurring floating material such as feathers, wood, and microalgae, because plastics offer different conditions, including the capacity to last much longer without degrading.

On the other hand, the scientists also found evidence that microbes may play a role in degrading plastics. They saw microscopic cracks and pits in the plastic surfaces that they suspect were made by microbes embedded in them, as well as microbes possibly capable of degrading hydrocarbons.

“When we first saw the ‘pit formers’ we were very excited, especially when they showed up on multiple pieces of plastic of different types of resins,” said Zettler, who added that undergraduate students participating in SEA Semester cruises collected and processed the samples. “Now we have to figure out what they are by [genetically] sequencing them and hopefully getting them into culture so we can do experiments.”

The plastic debris also represents a new mode of transportation, acting as rafts that can convey harmful microbes, including disease-causing pathogens and harmful algal species. One plastic sampled they analyzed was dominated by members of the genus Vibrio, which includes bacteria that cause cholera and gastrointestinal maladies.

The project was funded by a National Science Foundation Collaborative grant, a NSF TUES grant, and a Woods Hole Center for Oceans and Human Health Pilot award.

Citation:

Zettler ER, Mincer TJ, and Amaral-Zettler LA (2013) Life in the ‘Plastisphere’: Microbial communities on marine plastic debris. Env. Sci. & Tech. DOI: 10.1021/es401288x

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About Marine Biological Laboratory

The Marine Biological Laboratory (MBL) is dedicated to scientific discovery and improving the human condition through research and education in biology, biomedicine, and environmental science. Founded in 1888 in Woods Hole, Massachusetts, the MBL is an independent, nonprofit corporation.

About Sea Education Association

Sea Education Association (SEA) was founded in 1971 as a nonprofit educational institution, which provides challenging multi-disciplinary academic programs ashore and at sea.  Its 12-week SEA Semester program for college undergraduates integrates marine science, maritime literature, history and policy, and practical seamanship with deep-water oceanographic research.  Since its founding more than 7,000 students have participated in its programs. For more information, please visit www.sea.edu.

About Woods Hole Oceanographic Institution
The Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate a basic understanding of the ocean’s role in the changing global environment. For more information, please visit www.whoi.edu.