Resistant calcification responses of Arctica islandica clams under ocean acidification conditions

• Published in: Journal of experimental marine biology and ecology 2023-03, Vol.560, p.151855, Article 151855
• Main Authors: Liu, Yi-Wei, Wanamaker Jr, Alan D., Aciego, Sarah M., Searles, Ian, Hangstad, Thor Arne, Chierici, Melissa, Carroll, Michael L.
• Format: Article
• Language: English
• Subjects: Aragonite undersaturation; Barents Sea; Bivalve shell growth; Cross-population response; Norway; Sclerochronology
• ISSN: 0022-0981; 1879-1697
• DOI: 10.1016/j.jembe.2022.151855

Ocean acidification (OA) directly impacts marine calcifying organisms including ecologically and commercially important shellfish species such as Arctica islandica (A. islandica). To test whether documented growth resilience of A. islandica to OA is a general response across ages and populations or a function of adaptation to local habitat, we cultured juvenile and adult clams collected from an environment with little pH variation under four pH levels (7.5, 7.7, 7.9, and 8.1) for three months and integrated our understanding with relevant literature. The average shell growth over the experiment among all (69) individuals was 57 ± 55 μm, and there were no statistically significant differences in growth among pH treatments, including the control treatment, despite the general growth rate differences between juveniles and adults. Our results show that A. islandica can maintain its shell growth even in aragonite undersaturated (Ω < 1) conditions (0.65 and 0.83 for pH 7.5 and 7.7 treatments, respectively), supporting the hypothesis that resistance to OA conditions is likely a generalized response across populations. Although the present results show A. islandica can maintain their shell growth under short-term OA, long-term impacts of OA on A. islandica shell growth and other physical parameters including shell density and microstructure are still needed to better assess the sustainability of A. islandica in a more acidified future and to provide guidance on managing this important shellfish stock. •We cultured both juvenile and adult A. islandica collected from northern Norway under a range of pH•Arctica islandica from Norway can maintain its shell growth even in aragonite undersaturated (Ω < 1) conditions.•Our results show that shell growthresilience in acidified seawater is likely a multi-population adaptation in A. islandica.