| Summary: | Ocean acidification and global warming are largely caused by increased levels of atmospheric CO2, and marine fish are exposed to both these stressors simultaneously. Although the effects of temperature on fish have been investigated over the last century, the effects of moderate CO2 exposure and the combination of both stressors are not well-understood, especially long-term effects. In Papers I, II and III we investigated the protein expression and biochemical parameters in gills, blood plasma, and liver of Atlantic halibut (Hippoglossus hippoglossus) exposed to temperatures of 5, 10, 12 (control), 14, 16, and 18 °C (impaired growth) in combination with control (400 µatm) or elevated CO2 (1000 µatm) levels for 3 months. Paper I shows the protein expression in gills and blood plasma of halibuts exposed to elevated CO2 at 12 °C and 18 °C. Elevated CO2 induced the regulation of immune system-related proteins in plasma of fish from both temperature treatments. Gills from fish exposed to elevated CO2 at control temperature show modulation of energy metabolism proteins, as well as indications of increased cellular turnover and apoptosis signalling; while gills from fish exposed to both elevated CO2 and elevated temperature indicate increased expression of energy metabolism proteins. In conclusion, moderate CO2-driven acidification, alone and combined with increased temperature, can elicit biochemical changes that may affect fish health. To further investigate the findings in Paper I we analysed non-specific immune components in blood plasma (Paper II), and examined the occurrence of oxidative stress in liver (Paper III) of Atlantic halibut exposed to elevated CO2 at 5, 10, 12, 14, 16, and 18 ºC. Paper II reveals that both measured immune components (lysozyme and complement system) had increased activities in response to elevated CO2, which is consistent with the findings of Paper I. These changes represent an additional energetic cost for fish. Paper III indicates the occurrence of oxidative stress, which can damage ...
|
|---|