Thriving Colonies Of Microbes In The Ocean's Plastisphere — Plastic Pollution In The Ocean Is Altering Environmental Conditions By Transporting Microbes
A very diverse array of microbes has been found to be colonizing and thriving on the micro-plastic pollution that is now ubiquitous throughout the world’s oceans by new research from the Sea Education Association, the Woods Hole Oceanographic Institution, and the Marine Biological Laboratory. This vast and new ecological habitat of microbial communities has been dubbed the “plastisphere”.
According to the researchers 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 new research was done by analyzing a variety of marine plastic debris — skimmed from the sea surface at several different sites in the North Atlantic Ocean.
“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 Linda Amaral-Zettler of the Marine Biological Laboratory (MBL). “Are they sinking to the bottom of the ocean? Are they being ingested? If they’re being ingested, what impact does that have?”
The Woods Hole Oceanographic Institution explains the specifics of the research:
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 Tracy Mincer from Woods Hole Oceanographic Institution (WHOI). “They supply a place that selects for and supports distinct microbes to settle and succeed.”
It’s very likely — according to the researchers — that these communities are very 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.”
The researchers 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 Erik Zettler from Sea Education Association (SEA), 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 new research was just published online in the journal Environmental Science & Technology.