Program

Special Session 1: Ecosystem under multiple stressors

Poster

Seawater acidification increases physiological toxicity of nano-TiO2 in the mussel Mytilus coruscus
SS1-17
Youji Wang* , Shanghai Ocean University
Daohui Lin, Zhejiang University
Xizhi Huang, Shanghai Ocean University
Yueyong Shang, Shanghai Ocean University
Yi Hu, Zhejiang University
Menghong Hu, Shanghai Ocean University
Yimin Chen, Shanghai Ocean University
Weiqun Lu, Shanghai Ocean University
Presenter Email: yj_wang@shou.edu.cn

The increasing production and use of nanoparticles (NPs) have caused a considerable release into the aquatic environment, posing a potential threat to aquatic organisms. Meanwhile, anthropogenic CO₂ emissions have caused a reduction of seawater pH, which is called as ocean acidification. In view of both phenomena will occurring simultaneously in the natural environment, their combined effects on marine species must be experimentally evaluated. The purpose of this study was to estimate whether the physiological toxicity of nano-TiO₂ (mixed rutile/anatase phase, 7/3) in the thick shell mussel Mytilus coruscus is affected by seawater acidification. Juvenile mussels were exposed to six combined treatments with three nano-TiO₂ concentrations (0, 2.5 mg l^–1 and 10 mg l^–1) under two pH levels (8.1 and 7.3) for 14 days. We found that clearance rates (CR), food absorption efficiencies (AE), respiration rates (RR), scope for growth (SFG) and O:N ratios were significantly reduced by nano-TiO2 during the whole experiments, whereas faecal organic weight rate (E) and ammonium excretion rates (ER) were increased under nano-TiO₂ conditions. Low pH showed significant negative effects on CR, RR, ER and O:N ratio sometimes at certain nano-TiO₂ conditions, but showed almost no effects on AE, E and SFG of M. coruscus. Nevertheless, their interactive effects were observed in most physiological parameters except AE and E. PCA revealed positive relationships among most physiological indicators, i.e., CR, AE, RR, SFG and O:N ratio, whereas ER and E showed negative relationships to those parameters. PCA also showed that the normal physiological responses were closely correlated to an increasing SFG with normal pH and no/low nano-TiO₂ conditions. These results suggest that physiological energetics of juvenile M. coruscus are more severe impacted by the combination of nano-TiO₂ and seawater acidification than by a sole stressor. Therefore, the toxic effects of nano-TiO₂ on marine animals should be reconsidered when additional stressors may appear in the natural environment.