New research by academics at Anglia Ruskin University shows that the presence of microplastics in soils can stunt the growth of earthworms, and even cause them to lose weight – potentially having a serious impact on the soil ecosystem.
The scientists examined the impact of biodegradable polylactic acid (PLA), high-density polyethylene (HDPE), and microplastic clothing fibres (acrylic and nylon) on earthworms living in the soil as well as ryegrass sown on top. After 30 days in the presence of HDPE, which is commonly used in the production of plastic bottles and carrier bags, they found that rosy-tipped earthworms (Aporrectodea rosea) lost on average 3.1 per cent of their weight. In comparison, the earthworms living in control conditions, without added microplastics, saw weight increases of 5.1 per cent over the same period.
The study also found that the presence of HDPE decreased in the soil pH., and that soil containing PLA (a biodegradable form of plastic) saw reduced shoot height in the ryegrass (Lolium perenne), while both PLA and clothing fibres led to fewer ryegrass seeds germinating.
Lead author Dr Bas Boots, Lecturer in Biology at Anglia Ruskin University (ARU), said, “The earthworms lost weight overall when certain microplastics were present and grew significantly in weight in soil without added microplastics. However, the specific reasons for this weight loss needs unravelling. It may be that the response mechanisms to microplastics may be comparable in earthworms to that of the aquatic lugworms, which have been previously studied.”
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