The current trend of climatic alterations will accelerate the modification of the ocean system by, among other aspects, changing the metal speciation and its bioavailability which may have an impact in their accumulation by marine organisms. Understanding the impact of these potential changes is essential for future risk assessment of metal contamination. In the present study, we selected the species Mediterranean mussel (Mytilus galloprovincialis) as the main European aquaculture production bivalve and due to its widespread use for biomonitoring purposes. A long-term test (2 months) was carried out to explore the impact that global change in the marine environment (warming and CO2 increase) may exert on the accumulation of dissolved trace metals (Cu, Co, Pb, Cd, Cr, As and Ni) in different body parts of mussels (foot and soft tissue).
Studied mussels were collected at two different climatic locations (Atlantic and Mediterranean Sea) and exposed to unspiked, unpolluted seawater from the Vigo Ria (NW Iberian Peninsula). Results showed that under the global change conditions proposed in this study (1100 pCO2 and 25 °C), the increase in temperature resulted in a lower condition index and byssus strength for mussels from Atlantic Sea, while Mediterranean sea mussels, adapted to higher temperatures, did not show remarkable variations. According to trace metals accumulation in different body parts of the studied mussels, it was observed that the effect of increasing CO2 alone did not show to have an impact in the bioaccumulation, but the combined stressors (increase in CO2 and temperature) may lead to an increase in the bioaccumulation for some elements. The increase in temperature resulted in a decrease of the Cu content of foot tissue (byssus gland) in mussels from Atlantic Sea, which is in accordance with the lower byssus strength observed under such conditions. Our results indicate that the expected seawater temperature increase, which will be produced gradually during next decades, should be further study to ensure the species adaptability and aquaculture production.
