The damage caused by plastic products entering Earth’s oceans is well-documented and widely understood by the general public (at least in the developed parts of the world) and we know that plastics are often ingested by marine life. For the animals that don’t die as a result of that ingestion, researchers know that the chemicals derived from those plastics, such as PCBs (polychlorinated biphenyls), can become sequestered and concentrated in the animals’ tissues. Those chemicals are then passed-up the food chain and can ultimately reach humans, potentially causing nervous, immune, and endocrine system dysfunction in addition to impaired reproductive function and cancer (source).
It’s easy to imagine fish, sea turtles, or birds consuming plastics but there is an equally, if not more, devastating phenomenon happening mostly beyond the reach of the unaided human eye. Microscopic plastics formed by photodegradation or simply microscopic 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 seen 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.
A horror story unfolds in the plankton. One arrow worm eats a nematode alive while another eats a plastic microfibre and dies. pic.twitter.com/un4gAZb8uu
— Dr Richard Kirby (@PlanktonPundit) March 20, 2017
In another, various species of zooplankton interact with microfibers, sometimes becoming entangled and at other times consuming them.
These colourful plastic mirofibres are not pretty. We’re turning the plankton base of the sea's food chain into a rubbish tip. pic.twitter.com/jKMwqxKhAr
— Dr Richard Kirby (@PlanktonPundit) March 22, 2017
The consequences of this phenomenon extend well-beyond local effects on zooplankton populations. Since zooplankton serve as an initial pillar of the marine food-chain (one-step above phytoplankton), chemical pollution is therefore entering the marine food chain in its earliest stages and is therefore effecting the entire chain.
Furthermore, if plankton biodiversity begins to shift in response to these pollutants, the results could have profound effects for humanity that go well-beyond fisheries. The majority of the oxygen we depend on to breath is produced by plankton (phytoplankton) and other plant life in the ocean. While phytoplankton don’t ingest plastics, their health, diversity, and distribution is vulnerable to changes caused by perturbations in zooplankton health, diversity, and distribution. In other words, widespread damage caused by plastics in the core levels of Earth’s marine ecosystems will almost certainly cause profound damage to processes that drive Earth’s entire biosphere.
The phenomenon also focuses attention on the alarming prospect that we may not be able to clean up much of the micro-pollution currently in the ocean; that the damage is already done and we can only brace for the potential consequences. Unlike macroplastic pollution, which can be filtered through large sieves or tackled by community initiatives like beach clean-ups, the small size of microplastics and their distribution below the surface and within the water column make the prospect of removing them without causing further ecological damage something that is perhaps beyond our available technology and resources.
It is likely that in order to address this issue, society will need to focus its attention on changes in manufacturing processes, materials engineering and selection, and preventative measures (e.g. recycling, waste management and containment, etc.) that will inhibit further contamination. That, of course, will take time and cooperation in a era where some of the key powers-at-be deny the validity of scientific consensus rather than accept its guidance.