Microplastics influence physiological processes, growth and reproduction in the Manila clam, Ruditapes philippinarum

Microplastics (<5 mm) are widely distributed in marine environments and pose a serious threat to bivalves. Here, the ingestion and accumulation of polystyrene microplastics (PS microplastics, diameters 5 and 10 mu m) by the Manila clam, Ruditapes philippinarum, and their impacts on physiological processes, growth and reproduction were studied. The results showed that both PS microplastics were ingested by the Manila clam and accumulated in their gills, hepatopancreases and intestines. Furthermore, the accumulation of 5 and 10 mu m PS microplastics significantly increased the rates of respiration and excretion while significantly decreasing feeding and absorption efficiency (AE), leading to a dramatically reduced amount of energy available for growth (SfG) and ultimately led to slower growth. The dynamic energy budget (DEB) model predicts that PS microplastic exposure for 200 days would cause lower shell/flesh growth rates and reproductive potentiality. Transcriptomic profiles support these results, as carbon and protein metabolism and oxytocin and insulin-related signaling pathways were significantly altered in clams in response to PS microplastics. This study provides evidence that microplastics strongly affect the physiological activities, energy allocation, growth and reproduction of filter-feeding bivalves.

Automated summary

The study found that both 5 and 10 μm PS microplastics were ingested and accumulated in various organs of the Manila clam. This led to increased respiration and excretion rates, decreased feeding and absorption efficiency, and ultimately slower growth. The DEB model predicts negative impacts on growth and reproductive potentiality after 200 days of PS microplastic exposure. Transciptomic analysis revealed significant alterations in carbon and protein metabolism pathways in clams exposed to PS microplastics.