Acid-base balance in the haemolymph of European abalone (Haliotis tuberculata) exposed to CO2-induced ocean acidification

• Published in: Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
• Main Authors: Auzoux-Bordenave, Stéphanie, Chevret, Sandra, Badou, Aïcha, Martin, Sophie, Di Giglio, Sarah, Dubois, Philippe
• Other Authors: Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Station de Biologie Marine de Concarneau, Direction générale déléguée à la Recherche, à l’Expertise, à la Valorisation et à l’Enseignement-Formation (DGD.REVE), Muséum national d'Histoire naturelle (MNHN)-Muséum national d'Histoire naturelle (MNHN), Adaptation et diversité en milieu marin (ADMM), Institut national des sciences de l'Univers (INSU - CNRS)-Station biologique de Roscoff = Roscoff Marine Station (SBR), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Biologie Marine (LBM), Université libre de Bruxelles (ULB)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: ocean acidification; abalone; acid-base balance; haemolymph pH and alkalinity; buffer capacity pH on the Total scale; pH SW: seawater pH (total scale); pH HL : haemolymph pH (total scale); RCP 8.5: Representative Concentration Pathway 8.5; [SDV.BA]Life Sciences [q-bio]/Animal biology; Ocean acidification
• Online Access: https://hal.sorbonne-universite.fr/hal-03384734; https://hal.sorbonne-universite.fr/hal-03384734/document; https://hal.sorbonne-universite.fr/hal-03384734/file/Auzoux-Bordenave%20et%20al.%20-%202021%20-%20Acid%E2%80%93base%20balance%20in%20the%20h%C3%A6molymph%20of%20European%20aba.pdf; https://doi.org/10.1016/j.cbpa.2021.110996

International audience Ocean acidification (OA) and the associated changes in seawater carbonate chemistry pose a threat to calcifying organisms. This is particularly serious for shelled molluscs, in which shell growth and microstructure has been shown to be highly sensitive to OA. To improve our understanding of the responses of abalone to OA, this study investigated the effects of CO 2-induced ocean acidification on extra-cellular acid-base parameters in the European abalone Haliotis tuberculata. Three-year-old adult abalone were exposed for 15 days to three different pH levels (7.9, 7.7, 7.4) representing current and predicted near-future conditions. Haemolymph pH and total alkalinity were measured at different time points during exposure and used to calculate the carbonate parameters of the extracellular fluid. Total protein content was also measured to determine whether seawater acidification influences the composition and buffer capacity of haemolymph. Extracellular pH was maintained at seawater pH 7.7 indicating that abalones are able to buffer moderate acidification (-0.2 pH units). This was not due to an accumulation of HCO 3-ions but rather to a high haemolymph protein concentration. By contrast, haemolymph pH was significantly decreased after 5 days of exposure to pH 7.4, indicating that abalone do not compensate for higher decreases in seawater pH. Total alkalinity and dissolved inorganic carbon were also significantly decreased after 15 days of low pH exposure. It is concluded that changes in the acid-base balance of the haemolymph might be involved in deleterious effects recorded in adult H. 2 tuberculata facing severe OA stress. This would impact both the ecology and aquaculture of this commercially important species.