Exploring the effect of microparticles on bivalves: exposure of Mytilus galloprovincialis and Ruditapes philippinarum to both microplastics and silt

Abstract

Understanding the impacts of suspended sediments and microplastics (MPs) on aquatic organisms is critical, particularly for filter-feeding bivalves such as mussels and clams. Despite their ecological and economic significance, the differential effects of MPs and natural particles on bivalves remain insufficiently studied. This research investigates the impacts of polyethylene (PE) MPs, silt, and their combination on mortality and oxidative stress biomarkers (superoxide dismutase-SOD and malondialdehyde-MDA) in Mytilus galloprovincialis (mussels) and Ruditapes philippinarum (clams). PE exposure caused significant mortality, with clams showing greater sensitivity compared to mussels. In contrast, silt exposure resulted in minimal mortality, reflecting clams’ higher tolerance to natural particulate matter. However, combined PE and silt exposure exacerbated mortality in both species, highlighting synergistic effects. Combined exposure also led to a pronounced increase in SOD activity in the digestive glands of mussels and elevated MDA levels in both digestive glands and gills, indicating oxidative damage. Notably, single treatments with PE or silt also caused significant increases in MDA levels in mussels. Species interactions also significantly influenced the biochemical responses of mussels and clams. Overall, mussels showed the higher MP retention capacities, while clams appeared to modulate MP accumulation dynamics. This study advances our understanding of the ecological risks posed by particulate pollutants, particularly MPs, and highlights the importance of investigating the combined effects of multiple stressors in aquatic ecosystems.