Coast KZN

07 Nov 2016

Plastic health threat

Tony Carnie (The Mercury)

Bits enter fish, human systems.

They say that what goes around, comes around… And this may well be the case with the tons of plastic and toxins that humanity dumps into the sea each day, with tiny bits of polluted plastic eventually finding their way back into our stomachs and bloodstreams.

Preliminary findings from a series of marine biology research projects in KwaZuluNatal suggest it is happening already, with evidence that almost every fish species caught in a recent survey off the Durban coastline had plastic in their stomachs.

Several studies on the effects of plastic pollution in the sea were presented and debated at a conservation symposium in Howick on Friday by researchers from the University of KwaZulu-Natal. One of the biggest concerns involves “microplastics”, tiny pieces of plastic that can be swallowed very easily by fish.

Post-graduate student Sipho Mkhize outlined findings from a study in the Durban Bight, which detected microplastics in the guts of 34% of 16 different fish species. Of the 187 fish analysed, some form of plastic was found in the stomachs of all the species caught.

Fish with the most plastic in their guts were caught in the uThukela region south of Richards Bay, with suggestions that microplastics were more concentrated in some areas due to the effects of oceanic gyres (bodies of slowly-spinning sea water that can suck in tiny particles from great distances).

Separate research by Gemma Gerber, supervised by Dr Deborah Robertson-Andersson and Dr Gan Moodley, noted that toxic chemicals easily “adsorb” to microplastics (form a film on them), and that toxins absorbed by fish and other marine creatures will spread gradually through the sea food chain – ultimately reaching human dinner plates.

A third study by Travis Kunnen and Gemma Gerber notes that plastic pollution is ranked as one of the greatest threats to marine life. The aim of their study is to count and measure the size of microplastics in sea water samples – including tiny microplastics released from plastic textile fibres in local washing machines.

In a fourth presentation, titled “Microplastics make fish anally retentive!”, Matthew Coote presented evidence suggesting that microplastics remain in the digestive tract of fish significantly longer than the normal food swallowed by fish – and that this increased retention time could increase the level of chemicals and other pollutants in local fish.


Online Article