May 26, 2019

Plastic chemicals could harm the ocean bacteria that produce 10 percent of our oxygen

The dangers plastic bags, bottles and other products pose to marine life are all too familiar. Discarded plastics can physically choke ocean creatures, or build up in their bellies and pose a toxic threat. But our debris can also steep in the water, creating a dangerous tea. And that tea could erode the very foundation of marine ecosystems: the octillion or so (that’s 1 with 27 zeros) Prochlorococcus bacteria that produce an estimated 10 percent of our oxygen.

Prochlorococcus are the most numerous photosynthesizing organisms in the world. They suck up carbon dioxide, just like plants, storing the carbon in their cells. And they release oxygen into the atmosphere. In short, these tiny bacteria play a huge role in supporting a habitable planet.

Scientists at Macquarie University wondered if the millions of tons of plastic sinking into the seas each year could pose a threat to these crucial organisms. They published their results in the journal Communications Biology.

Other studies have found that zooplankton, tiny marine animals such as baby crustaceans, get sick when submerged in a plastic-tainted water. But there was little plastic toxicity research on photosynthesizing organisms. And even if the current levels of plastic tea, or leachate, aren’t all that high yet, the study sounds an alarm about our reliance on the ubiquitous material, according to author Lisa Moore, molecular scientist at Macquarie University in Sydney. “Even some of the most abundant organisms could be potentially damaged if the waste continues to increase and we don’t do anything about it.”

So the team made two different types of plastic tea: one with high density polyethylene (HDPE), the stuff plastic grocery bags are made of, and another with polyvinyl chloride (PVC), which is, yes, in PVC piping but also in many other materials, including the sticky matting used to keep rugs from sliding. They then bathed two strains of these cyanobacteria in different concentrations of the leachates for three days, measuring the growth of their cells, oxygen production, and the activity of their gene transcription.

Leave a Reply