It has been estimated that the ocean contains around 5.25 trillion pieces of plastic, with a staggering 99.9% of floating marine debris made from plastic.
New research is showing that chemicals leached from plastic products into our oceans are also harming some of the tiniest marine organisms - oxygen-producing cyanobacteria. They may not be as emblematic as whales or sea turtles in the devastation caused by our plastic addiction but their role in sustaining human existence is vital.
PROCHLOROCOCCUS IS A GENUS OF TINY MARINE CYANOBACTERIA THAT ARE AMONG THE MOST ABUNDANT PHOTOSYNTHETIC ORGANISMS ON EARTH, NUMBERING AROUND AN OCTILLION (EQUAL TO 1 FOLLOWED BY 27 ZEROS).
Prochlorococcus produce around 10% of our oxygen needs by sucking up carbon dioxide and storing the carbon in their cells while releasing oxygen back into the atmosphere. Until recently, there was little research into the effects of plastic toxicity on photosynthesizing organisms, although scientists did know that zooplankton became ill when submerged in plastic “tea” or leachate.
Once plastic makes its way into the ocean, it is broken down by sunlight and the action of the waves and wind, releasing chemical additives as it fragments.
THESE CHEMICALS HAVE SHOWN TO HAVE DETRIMENTAL EFFECTS ON MARINE LIFE, INCLUDING REDUCED REPRODUCTION AND EGG HATCHING RATES IN FISH, AS WELL AS LEADING TO CARDIOVASCULAR DISEASES AND CANCER IN HUMANS.
Researchers at Macquarie University in Sydney decided to look at how these chemical additives might impact Prochlorococcus by preparing two different types of plastic tea - one contaminated with high-density polyethylene (HDPE) (which is leached from plastic grocery bags) and another with polyvinyl chloride (PVC) (which is found in PVC piping and a range of other plastic materials).
Into these two preparations, they placed two strains of cyanobacteria and measured the impact on them over three days. Aside from measuring the growth of their cells and their gene transcription, they also recorded their oxygen production rates.
Both strains recorded significant population losses, with more bacteria dying in more concentrated plastic “tea”. Photosynthesis rates were also reduced, meaning the bacteria produced far less oxygen. Interestingly, it was the PVC preparation that had a more toxic effect, perhaps due to the additives that are used in its manufacture. According to the author of the report, Lisa Moore, a molecular scientist at Macquarie University, the “toxins to blame for the bacteria’s poisoning likely include both organic (carbon-based) compounds and heavy metals, like zinc”.
But she also went on to say: “Levels of leachate aren’t going to be as high as what we have in the lab. We’re not saying the Pacific Garbage Patch is killing the bacteria.” So, while the findings are of concern, they’re not indicative of what is currently happening in our oceans but, rather, a warning of the many ways that plastic impacts our marine life and the potential harm it could cause in the long run. The importance of oxygen levels to global temperature and humidity levels should not be understated, nor should the role that these cyanobacteria play in ensuring that our marine ecosystems are healthy.
Aside from ongoing research into the effects of plastic leachate on bacteria in our oceans, the results from the Macquarie University study should be a catalyst for taking active steps to better manage our use of plastics. We can be proactive in altering the manufacturing process to make plastics less toxic and reduce the risks associated with chemical leachate in our oceans. First and foremost, we need to reduce the amount of plastic waste that is entering our oceans in the first place by reducing our use of plastics in day to day life. Recycling initiatives need to be drastically improved to divert plastics away from landfills and ensure they don’t end up in waterways where they can easily be flushed out to sea. Also crucial is addressing the issue of waste that is produced by the global fishing industry, with broken fishing nets accounting for almost half of all the waste found in the Great Pacific Garbage Patch.
But perhaps the most pressing need for oxygen-producing bacteria is legislation that limits the industrial use of harmful chemical additives in plastic products. Not only do we need to physically remove plastic waste, as is being done with the Ocean Clean Up and 4ocean LLC projects, but we should also be investing in chemical removal technologies to eliminate harmful leachate from our oceans.
In total, it’s estimated that plastic waste currently accounts for more than US$13 billion in economic damage to our marine ecosystems each year. With worldwide plastic production on the increase and the environmental degradation rates of plastics still devastatingly slow, we’re headed for both an economic and ecological disaster if action isn’t taken soon.
Oxygen-producing cyanobacteria may seem “out of sight, out of mind” but these tiny organisms play a larger-than-life role in maintaining a balanced ecosystem and ensuring life on Earth.
Images: Hero and Prochlorococcus - I Dive Blue / Whale and Sea Flora - Unsplash | NOAA
As researchers say, the finding is troubling. The plastic has POTENTIAL to kill the oxygen-producing bacteria. But its not as troubling as your You headline suggests. Yes, it attracts the attention (as intended) but it may annoy the reader as the "green wash". Because we are already in the midst of a sixth mass extinction event. Like right now. https://www.sciencealert.com/here-s-how-biodiversity-experts-recognise-that-we-re-midst-a-mass-extinctionThe potential of plastic pollution is indeed a serious issue but probably not the biggest issue right now. Tuesday, 5 January 2021