Enviros See Armageddon In Every Plastic BagWe are told the oceans are covered with floating plastic debris, clogging the ocean food chains and destroying free-swimming wildlife. But solid evidence of this eco-catastrophe is quite thin. And ever since
a Canadian high-schooler (and another in Taiwan) in 2009 discovered species of microbes that thrive on eating plastic, most informed observers have been somewhat less concerned.
Since then,
scientists in Ireland have begun to put microbes to work digesting waste plastics, and
UK scientists have discovered plastic-eating microbes in ocean waters.
Sargasso SeaThe latest story in the long-running ocean apocalypse saga, involves scientists from the Woods Hole Oceanographic Institute in Massachusetts. Woods Hole scientists explored the Sargasso Sea, in search of plastic-eating bacteria.
Mincer and his colleagues examined bits of fishing line, a plastic bag and a plastic nurdle (a pre-production plastic pellet) fished out of the Sargasso Sea, an area of the North Atlantic where currents cause debris to accumulate. The region as a whole contains more than 1,100 tonnes of plastic1.
...Plastic-eating bacteria might help explain why the amount of debris in the ocean has levelled off, despite continued pollution. But researchers don't yet know whether the digestion produces harmless by-products, or whether it might introduce toxins into the food chain.
...Genetic analysis shows that the bacteria on the plastic differ from those in the surrounding seawater or on nearby seaweed, says microbiologist Linda Amaral-Zettler of the Marine Biological Laboratory, Woods Hole. So far, the DNA sequences obtained by her lab show that almost 25% of the bacteria on one polyethylene surface were vibrios, bacteria from the same group as the cholera bacterium.
...Amaral-Zettler and Mincer also found genetic and microscope evidence of eukaryotes — organisms with more complicated cells than bacteria — on the plastic. What she calls the "plastisphere" might contain complex living communities. "It may be a little world that we've created, for better or worse." _Nature_via_Impactlab
It is fascinating that particular ocean bacteria have adapted to using plastics as a food source. This is all quite reminiscent of the bacteria that have adapted to eating crude oil and methane gas around oil spills and and natural hydrocarbon seeps in the ocean floor.
To the bacteria, our discarded plastics are a feast and a windfall, allowing them to feed and reproduce to their microbial hearts' content. Of course the same phenomena occurs on land, except with a much wider range of microbes -- both prokaryotic and eukaryotic -- partaking of the cornucopian repast.
Environmentalists are concerned that the microbes may be releasing toxins into the seawater which will pollute larger sea creatures and perhaps get into the human food chain. A plastic apocalypse on the prowl, don't you see? And yet, in the middle of the ocean, nothing is wasted. If something can be seen as food, it will be used as food by something. That includes anything which humans may perceive as toxic.
Here is the amusing thing in all this:
Waste plastics are increasingly being seen as valuable feedstocks in the production of synthetic fuels, chemicals, and other high-value substances. Gasification of solid wastes for production of power, process heat, and chemical/fuel feedstock is just getting started in the developed world. In the future, the only plastic wastes the oceans will see will be coming from places too primitive to know how to unlock their intrinsic value.
And no doubt there will be plenty of plastic-eating ocean microbes to take care of those remnants. Otherwise we will need to raise our seawalls quite high, to avoid the ocean plastic tsunamis that may come from Neptune, with a crashing vengeance.
Beware the plastic apocalypse.
More on plastic apocalypse 31March11:
The death of the environment by plastic bags may have been exaggerated. (via
Daily Bayonet)
