Revisiting Cape Basin plastic, 31 years later…

Anna Cummins from 5 GYRES South Atlantic Expedition

Current Position: 33 51.133, 10 46.651

3 days to go, and racing to make our Dec. 8th arrival. On the weather charts, a nasty, foreboding red patch awaits us, signifying more 30-40 knot winds. Ah well, by now the crew are used to it…

With our final 7 trawls, we have an extremely cool opportunity to repeat one of the only other studies done on surface plastics in the South Atlantic. In 1979, Robert Morris (Institute of Oceanographic Sciences, UK) conducted a study on floating plastics in the surface waters of Cape Basin, aboard the R.R.S Discovery. Using a neuston tow – just like like our Manta Trawl, Morris gathered 9 samples, finding HDPE and PP plastic pellets in 7, and tarballs in every one.

Starting at 4:50 am this morning, we’re revisiting Morris’s sample sites, trawling at the same coordinates to see how things changed in a few decades. Any guesses? The first of these trawls we are dedicating to Nature Safe, one of our sponsors supporting this particular tow. With their support, we’re able to collect, process, and publish the results of this sample – the crux of our work. Philisophically, Nature Safe is a perfect fit – this Australian company  provides EcoTanka stainless steel waterbottles, an alternative to throwaway plastics. 2 weeks ago, near the center of the South Atlantic Gyre, we found a plastic waterbottle bobbing on the oceans surface. An unfortunate example of the darker side of our disposable addiction. Any readers who haven’t yet made the switch – now is the time…..

Flipping through Morris’s original study “Plastic Debris in the Surface Waters of the South Atlantic”, I’m intrigued to note that several questions he poses remain unanswered today, 31 years later:

1) The potential impacts of plastic on marine wildlife. “Those plastics containing PCBs and phthalates as plasticizers could well be a source of these compounds which are known contaminants of ocean waters and organisms…..The possible dangers to marine life of these floating particles has received considerable attention, but the data are conflicting.”

2) Morris notes that his results overall will likely be underestimated, as gathering surface samples with 100% accuracy is near impossible. What’s interesting: he notes that at the time of his work, “sampling efficiency is estimated to range from 25 – 50% depending on sea state”.

This unresolved question of how sea state impacts plastics’ buoyancy is something we’ve wondered about in the last few weeks. On this expedition we’ve sampled in some less than ideal conditions – i.e. raging storms – and still found plastic in our trawls. Though we may have to exclude some of these samples from our publishable results, its still valuable to note that plastic still remains at the surface despite churning waves and gale force winds.

Marcus is already dreaming up a multi-layered manta that will sample at different depths, to see how sea state impacts plastics location in the water column. Perhaps a study for the South Pacific.

Finally, Morris’s suggestion for international cooperation is, we hope, coming true. In his 1980 paper, Morris calls for attention from UNEP: 

“Clearly a strong lead is required from an international environmental organization such as UNEP if this problem is to be seriously tackled. Only in this way can satisfactory pollution control measures for plastic waste become the norm and be effective.”

5 Gyres is now working actively with UNEP’s Safe Planet Campaign on Hazardous Chemicals and Waste, and will be holding an international press conference in Cape Town with UNEP to share our findings. We’re hopeful that as more international bodies learn that plastic pollution is a global issue, stemming from every continent in the world, more partnerships like this will emerge. This is why were here.


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