The damage caused by plastics in the Earth’s oceans is well-documented. Plastics are commonly ingested by marine life and the chemicals therein, such as PCBs (polychlorinated biphenyls), can become sequestered and concentrated in marine animal tissues. Those chemicals are then passed up the food chain, sometimes reaching back to humans. Once in human bodies, they have the potential to cause nervous, immune, and endocrine system dysfunction in addition to impaired reproductive function and cancer (source).
It’s common to see images of fish, sea turtles, and birds consuming plastics but there is an equally, if not more, devastating phenomenon happening beyond the reach of the human eye. Microscopic plastics formed by photodegradation or simply by virtue of their inherent small size (e.g. microfibers) are being consumed by zooplankton.
Dr. Richard Kirby, a ‘plankton pundit’ based at the Marine Biological Association, is bringing this issue into focus through some spectacular video evidence. In excerpts shared by Dr. Kirby on Twitter, zooplankton can be recorded ingesting plastic microfibers, sometimes with fatal results.
In one clip, an arrow worm (Sagittidae) is shown with a complete bowel obstruction caused by a looping microfiber filament in its gut.
In another, various species of zooplankton interact with microfibers, sometimes becoming entangled and at other times consuming them.
The consequences of this phenomenon extend well beyond local effects on zooplankton populations. Since zooplankton is a foundational element of the entire marine food chain, the plastics they consume affect the entire marine food chain.
Plankton biodiversity could also begin to shift in response to these pollutants. That could have profound effects for humanity that go well beyond fisheries. The majority of the oxygen we breathe is produced by plankton (phytoplankton) and other plant life in the ocean. While phytoplankton doesn’t ingest plastics, their health, diversity, and distribution are vulnerable to changes caused by perturbations in zooplankton health, diversity, and distribution.
In other words, widespread damage caused by plastics on planktonic biodiversity will almost certainly cause profound damage to processes that drive Earth’s entire biosphere.
Unfortunately, we may not even be able to clean up these plastics effectively. Macroplastic pollution can often filtered through large sieves or tackled by community initiatives like beach clean-ups. Microplastics are more difficult to recapture. They can be found throughout the water column and it’s hard to collect them without damaging the surrounding environment further. Trying to capture them with super fine nets, for instance, would quickly involve unwanted bycatch.
In order to actually address this issue, society will change its manufacturing processes, materials engineering and selection, and preventative measures (e.g. recycling, waste management, and containment, etc.) in order to limit further contamination. That, of course, will take time and cooperation in a era where so many powers-at-be deny the validity of scientific consensus rather than accept its guidance.