Seawater carbonate chemistry and hypoxia tolerance and blood chemistry characteristics of European sea bass

• Main Authors: Montgomery, Daniel W, Simpson, Stephen D, Engelhard, Georg H, Birchenough, Silvana N R, Wilson, Rod W
• Format: Dataset
• Language: English
• Published: PANGAEA 2019
• Subjects: Acid-base regulation; Alkalinity; total; standard deviation; Animalia; Aragonite saturation state; Bicarbonate ion; Blood; bicarbonate; partial pressure of carbon dioxide; ph; Brackish waters; Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; partial pressure; Chordata; Containers and aquaria (20-1000 L or < 1 m**2); Covariance; Date; Dicentrarchus labrax; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Haematocrit; Half saturation partial pressure of oxygen; Hill coefficient; Identification; Laboratory experiment; Mass; Metabolic rate; standard; Nekton; North Atlantic; OA-ICC; Ocean Acidification International Coordination Centre; Other studied parameter or process; Oxygen; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.914653; https://doi.org/10.1594/PANGAEA.914653

Global environmental change is increasing hypoxia in aquatic ecosystems. During hypoxic events, bacterial respiration causes an increase in carbon dioxide (CO2) while oxygen (O2) declines. This is rarely accounted for when assessing hypoxia tolerances of aquatic organisms. We investigated the impact of environmentally realistic increases in CO2 on responses to hypoxia in European sea bass (Dicentrarchus labrax). We conducted a critical oxygen (O2crit) test, a common measure of hypoxia tolerance, using two treatments in which O2 levels were reduced with constant ambient CO2 levels (~530 µatm), or with reciprocal increases in CO2 (rising to ~2,500 µatm). We also assessed blood acid-base chemistry and haemoglobin-O2 binding affinity of sea bass in hypoxic conditions with ambient (~650 μatm) or raised CO2 (~1770 μatm) levels. Sea bass exhibited greater hypoxia tolerance (~20% reduced O2crit), associated with increased haemoglobin-O2 affinity (~32% fall in P50) of red blood cells, when exposed to reciprocal changes in O2 and CO2. This indicates that rising CO2 which accompanies environmental hypoxia facilitates increased O2 uptake by the blood in low O2 conditions, enhancing hypoxia tolerance. We recommend that when impacts of hypoxia on aquatic organisms are assessed, due consideration is given to associated environmental increases in CO2.