Sifting, sorting, finding and thinking: An insight into research on microplastics in the marine environment
By: Andrew Chin, James Cook University, Australia
We’ve all seen those iconic images of plastic trash draped over reefs, or photos of dead or injured marine animals entangled or struggling in carelessly discarded debris. And who can forget the viral video of mantas swimming through a sea of floating plastic trash? You don’t need to be a genius to see that plastic is having a massive effect on our reefs and marine life.
However, the invasion of microplastics in our ocean, tiny plastic particles smaller than five millimetres, is much harder to see. It’s also hard to trace where these microplastics come from and where they end up, and the impacts these are having on our reefs and oceans.
Nevertheless, microplastics are the focus of a group of dedicated researchers at James Cook University (JCU) and the Australian Institute of Marine Science (AIMS), and microplastic research is more difficult than it sounds.
Microplastics can be really hard to accurately isolate and count. If you’re looking for them in the environment, you need to strain seawater, sift through sediment, or look inside animals to find these tiny particles and fibres. Imagine a bucket of beach sand, or the slimy, partially digested contents of a fish or turtle’s stomach. How do you properly separate out all the tiny plastic fragments from these contents?
Well, JCU and AIMS researchers have developed new techniques of chemically digesting, separating, and identifying microplastics from difficult materials such as turtle stomachs. The process includes using infrared spectroscopy, a tricky technique where samples are blasted with infrared light. The researchers then interpret the resulting absorption, emission and reflection spectra to work out what type of plastic it is.
Sensing the Scale
Testing the protocol on turtles, the research team found paint chips and synthetic fabric particles in turtle stomachs1. It’s a big problem. Another research team that included JCU scientists found plastics in the stomachs of every single one of 102 turtles examined, the most common being fibres from clothing, tyres, cigarette filters, and maritime equipment such as ropes and fishing nets2. While small amounts of microplastics may not be enough to block the digestive system, they could be leaching toxic chemicals into the animals that ingest them, an issue that needs to be studied.
And it’s not just turtles: Even fish such as the iconic coral trout (Plectropomus spp) have been found to have plastic in their guts3. It’s not just divers and conservationists who are worried about this; fishing industry representatives have called for more research on the effects ingested plastics could have on fish health and reproduction.
For the rest of this article (Asian Diver 2019 Issue 1 No 152) and other stories, check out our past issues here or download digital copy here. The 25th anniversary of the largest and longest running dive show, Asia Dive Expo (ADEX) is set to occur on the 11-14th April 2019. Centred on the theme – Plastic free Future, ADEX is more than just a dive show with its commitment to the environment.
So join us at the event, get inspired and for all you know, you might just liberate the inner diver in you! More details of the event here.