Seawater carbonate chemistry and aerobic capacities and swimming performance of polar cod (Boreogadus saida)

• Main Authors: Kunz, Kristina Lore, Claireaux, Guy, Pörtner, Hans-Otto, Knust, Rainer, Mark, Felix Christopher
• Format: Dataset
• Language: English
• Published: PANGAEA 2018
• Subjects: Aerobic scope; oxygen; Alkalinity; total; standard deviation; Animalia; Aragonite saturation state; Arctic; Behaviour; Bicarbonate ion; Boreogadus saida; Burst counts; maximum; mean; Burst counts per velocity step; Calcite saturation state; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Calculated using seacarb after Orr et al. (2018); Carbon; inorganic; dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Chordata; Coast and continental shelf; Containers and aquaria (20-1000 L or < 1 m**2); Estimated investment; anaerobic; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Fugacity of carbon dioxide in seawater; atlantic cod; Climate change; Gadus morhua; Ocean acidification; polar cod
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.922147; https://doi.org/10.1594/PANGAEA.922147

Oceans are experiencing increasing acidification in parallel to a distinct warming trend in consequence of ongoing climate change. Rising seawater temperatures are mediating a northward shift in distribution of Atlantic cod (Gadus morhua), into the habitat of polar cod (Boreogadus saida), that is associated with retreating cold water masses. This study investigates the competitive strength of the co-occurring gadoids under ocean acidification and warming (OAW) scenarios. Therefore, we incubated specimens of both species in individual tanks for 4 months, under different control and projected temperatures (polar cod: 0, 3, 6, 8 °C, Atlantic cod: 3, 8, 12, 16 °C) and PCO2 conditions (390 and 1170 µatm) and monitored growth, feed consumption and standard metabolic rate. Our results revealed distinct temperature effects on both species. While hypercapnia by itself had no effect, combined drivers caused nonsignificant trends. The feed conversion efficiency of normocapnic polar cod was highest at 0 °C, while optimum growth performance was attained at 6 °C; the long-term upper thermal tolerance limit was reached at 8 °C. OAW caused only slight impairments in growth performance. Under normocapnic conditions, Atlantic cod consumed progressively increasing amounts of feed than individuals under hypercapnia despite maintaining similar growth rates during warming. The low feed conversion efficiency at 3 °C may relate to the lower thermal limit of Atlantic cod. In conclusion, Atlantic cod displayed increased performance in the warming Arctic such that the competitive strength of polar cod is expected to decrease under future OAW conditions.