Effects of hypoxia on the olfactory sensitivity of gilt-head seabream (Sparus aurata)

Coastal environments around the world are becoming increasingly hypoxic owing to anthropogenic effects. We hypothesized that, because the olfactory epithelium is in contact with the external environment, decreased external oxygen will impair olfaction. We performed electro-olfactograms on juvenile gilt-head seabream (Sparus aurata) and measured the response to three amino acids at five different concentrations (1×10−7 to 1×10−3 mol l−1) in normoxic (20 kPa O2) and two hypoxic conditions (12.5 and 5.7 kPa O2). For the first time, we show that both mild and moderate hypoxia decreased the olfactory response to two out of three odorants. As more coastal areas become hypoxic, it is important to understand how hypoxia may impair the sensory systems of fishes, which can have individual- and population-level effects and important implications for our food supply.