Physiological impacts of acute Cu exposure on deep-sea vent mussel Bathymodiolus azoricus under a deep-sea mining activity scenario

• Published in: Aquatic toxicology 2017-12, Vol.193, p.40-49
• Main Authors: Martins, Inês, Goulart, Joana, Martins, Eva, Morales-Román, Rosa, Marín, Sergio, Riou, Virginie, Colaço, Ana, Bettencourt, Raul
• Format: Article
• Language: English
• Subjects: Animals; Bathymodiolus azoricus; Copper; Copper - toxicity; Deep-sea mining; Gastrointestinal Tract - drug effects; Gastrointestinal Tract - metabolism; Gills - drug effects; Gills - metabolism; Hydrothermal Vents; Lipid Peroxidation - genetics; Mining; Molecular biomarkers; Mytilidae - drug effects; Mytilidae - metabolism; Oxidative Stress - genetics; Physiological stress; Up-Regulation; Water Pollutants, Chemical - toxicity
• ISSN: 0166-445X; 1879-1514
• DOI: 10.1016/j.aquatox.2017.10.004

•B. azoricus was exposed to high Cu concentrations under pressurized conditions.•High Cu concentrations cause serious changes in cellular defense mechanisms of B. azoricus.•Enzymatic and transcriptional response to high Cu concentration exposure is tissue-specific.•Exposure to high Cu concentrations causes a decrease in enzyme activity and transcriptional suppression in mussel gills. Over the past years, several studies have been dedicated to understanding the physiological ability of the vent mussel Bathymodiolus azoricus to overcome the high metal concentrations present in their surrounding hydrothermal environment. Potential deep-sea mining activities at Azores Triple junction hydrothermal vent deposits would inevitably lead to the emergence of new fluid sources close to mussel beds, with consequent emission of high metal concentrations and potential resolubilization of Cu from minerals formed during the active phase of the vent field. Copper is an essential metal playing a key role in the activation of metalloenzymes and metalloproteins responsible for important cellular metabolic processes and tissue homeostasis. However, excessive intracellular amounts of reactive Cu ions may cause irreversible damages triggering possible cell apoptosis. In the present study, B. azoricus was exposed to increasing concentrations of Cu for 96h in conditions of temperature and hydrostatic pressure similar to those experienced at the Lucky Strike hydrothermal vent field. Specimens were kept in 1L flasks, exposed to four Cu concentrations: 0μg/L (control), 300, 800 and 1600μg/L and pressurized to 1750bar. We addressed the question of how increased Cu concentration would affect the function of antioxidant defense proteins and expression of antioxidant and immune-related genes in B. azoricus. Both antioxidant enzymatic activities and gene expression were examined in gills, mantle and digestive gland tissues of exposed vent mussels. Our study reveals that stressful short-term Cu exposure has a strong effect on molecular metabolism of the hydrothermal vent mussel, especially in gill tissue. Initially, both the stress caused by unpressurization or by Cu exposure was associated with high antioxidant enzyme activities and tissue-specific transcriptional up-regulation. However, mussels exposed to increased Cu concentrations showed both antioxidant and immune-related gene suppression. Under a mining activity scenario, the release of an excess of dissolved Cu to the vent environmen