Pilot study to investigate the effect of long-term exposure to high pCO2 on adult cod (Gadus morhua) otolith morphology and calcium carbonate deposition

• Published in: Fish Physiology and Biochemistry
• Main Authors: Coll-Lladó, Clara, Mittermayer, Felix, Webb, Paul Brian, Allison, Nicola, Clemmesen, Catriona, Stiasny, Martina, Bridges, Christopher Robert, Göttler, Gwendolin, Garcia de la serrana, Daniel
• Other Authors: Bundesministerium für Bildung und Forschung, European Observation Network for Territorial Development and Cohesion, Marine Alliance for Science and Technology for Scotland, Universitat de Barcelona
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Science and Business Media LLC 2021
• Subjects: Aquatic Science; General Medicine; Physiology; Biochemistry; atlantic cod; Gadus morhua; Ocean acidification
• Online Access: http://dx.doi.org/10.1007/s10695-021-01016-6; https://link.springer.com/content/pdf/10.1007/s10695-021-01016-6.pdf; https://link.springer.com/article/10.1007/s10695-021-01016-6/fulltext.html

Abstract To date the study of ocean acidification on fish otolith formation has been mainly focused on larval and juvenile stages. In the present pilot study, wild-captured adult Atlantic cod ( Gadus morhua ) were exposed to two different levels of p CO 2, 422µatm (ambient, low p CO 2 ) or 1091µatm (high p CO 2 ), for a period of 30 weeks (from mid-October to early April 2014–2015) in order to study the effects on otolith size, shape and CaCO 3 crystallization amongst other biological parameters. We found that otoliths from cod exposed to high p CO 2 were slightly smaller (− 3.4% in length; − 3.3% in perimeter), rounder (− 2.9% circularity and + 4% roundness) but heavier (+ 5%) than the low p CO 2 group. Interestingly, there were different effects in males and females; for instance, male cods exposed to high p CO 2 exhibited significant changes in circularity (− 3%) and roundness (+ 4%) compared to the low p CO 2 males, but without significant changes on otolith dimensions, while females exposed to high p CO 2 had smaller otoliths as shown for length (− 5.6%), width (− 2%), perimeter (− 3.5%) and area (− 4.8%). Furthermore, while the majority of the otoliths analysed showed normal aragonite deposition, 10% of fish exposed to 1091µatm of p CO 2 had an abnormal accretion of calcite, suggesting a shift on calcium carbonate polymorph crystallization in some individuals under high p CO 2 conditions. Our preliminary results indicate that high levels of p CO 2 in adult Atlantic cod might affect otolith growth in a gender-specific way. Our findings reveal that otoliths from adult cod are affected by ocean acidification, and we believe that the present study will prompt further research into this currently under-explored area.