Warming in shallow waters: Seasonal response of stress biomarkers in a tide pool fish

Tide pools are rapidly warming environments with low thermal inertia, where organisms are exposed to potentially stressful conditions. This way, tide pools will be among the first and hardest hit environments by climate warming. Studies of thermal stress in situ are rare, but important so that current thermal stress in the wild can be confirmed and serve as reference for the future. This study aims to investigate the seasonal response of stress biomarkers in a common tide pool fish, the blenny Lipophrys trigloides, under natural conditions, in situ. Multiple biomarkers of thermal and oxidative stress were analysed in the tissues of the muscle, visceral mass, gills and brain of L. trigloides, under spring (18.50 ± 0.71 °C) and summer conditions (28.30 ± 1.30 °C), in order to assess tissue-specific seasonal responses to the rapid warming that occurs seasonally in tide pools. It was concluded that L. trigloides seems to be setting in motion relevant thermal stress and antioxidant defences under summer conditions. All tissues analysed were responsive and all biomarkers of thermal and oxidative stress increased in summer conditions, with the exception of SOD, which presented no alterations. The present study offers reference values that will be useful for future comparison during particularly warm summers and in future years as climate warming progresses.