Impact of Exposure Routes of Copper Oxide Nanoparticles in the Clam Ruditapes decussatus

The increasing production of diverse applications of engineered nanoparticles along with their potential release into the marine environment from both point and diffuse sources have become a significant concern for ocean health. Due to their unique physical properties, particularly their high surface-to-volume ratio, these nanoparticles can exhibit enhanced bioavailability and toxicity to marine biota. Copper oxide nanoparticles (CuO NPs) are especially prevalent due to their wide range of commercial applications. In the aquatic environment, these nanoparticles typically become part of colloidal fraction and are subjected to physicochemical transformations, leading to the formation of aggregates that eventually sink and deposit onto the bottom substrate. Therefore, sediments, in addition to the water column, act as the primary route of exposure to benthic organisms. The clam Rudipates decussatus is a marine suspension-feeder of great ecological and economic importance in Europe. Ruditapes decussatus were exposed to CuO NPs (10 μg L−1) or an equivalent concentration of ionic copper (Cu2+) in both water and water/sediments matrices for 15 days to compare the toxicological impact of different exposure routes. Copper accumulation was monitored in both gills and digestive gland, alongside various biomarkers of susceptibility, exposure, and damage. The results revealed distinct uptake patterns that were dependent on the exposure routes, the chemical form of the metal and the specific tissue responses. Highlighting the complex impact of these contaminants on marine biodiversity.