Ocean Acidification Reduces Skeletal Density of Hardground‐Forming High‐Latitude Crustose Coralline Algae. Issue 5 (24th February 2021)

• Record Type: Journal Article
• Authors: Williams, B.; Chan, P. T. W.; Westfield, I. T.; Rasher, D. B.; Ries, J.
• Is Part Of: Geophysical research letters. Volume 48:Issue 5(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-02-24
• Subjects: calcium carbonate -- crustose coralline algae -- density -- global warming -- high‐latitude -- ocean acidification; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2020GL091499
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Crustose coralline algae (CCA) function as foundation species by creating marine carbonate hardground habitats. High‐latitude species may be vulnerable to regional warming and acidification. Here, we report the results of an experiment investigating the impacts of CO2 ‐induced acidification (pCO2 ∼350, 490, 890, 3, 200 µatm) and temperature (∼6.5°C, 8.5°C, 12.5°C) on the skeletal density of two species of high‐latitude CCA: Clathromorphum compactum and Clathromorphum nereostratum (CN). Skeletal density of both species significantly declined with pCO2 . In CN, the density of previously deposited skeleton declined in the highest pCO2 treatment. This species was also unable to precipitate new skeleton at 12.5°C, suggesting that CN will be particularly sensitive to future warming and acidification. The decline in skeletal density exhibited by both species under future pCO2 conditions could reduce their skeletal strength, potentially rendering them more vulnerable to disturbance, and impairing their production of critical habitat in high‐latitude systems. Plain Language Summary: Crustose coralline algae (CCA) are marine algae that grow a hard, rock like skeleton from calcium carbonate. Some species can live for hundreds of years in shallow, cold‐water environments throughout the northern hemisphere. Because of where they live, they are particularly vulnerable to changing ocean temperatures and chemistry. We grew two species of CCA in aquaria with different temperatures and atmospheric carbon dioxide concentrations to test for the impact of these conditions on their skeletons. We found that skeletal density was reduced by warming in one species and by high levels of carbon dioxide in both species. Therefore, future increases in temperature and carbon dioxide level will impair the ability of these CCA to provide hard surface habitats for other organisms, altering shelf ecosystems throughout the northern hemisphere. Key Points: Ocean acidification decreases skeletal density in two high‐latitude species of crustose coralline algae Density declined in previously calcified skeleton in undersaturated conditions in one species; this was enhanced under higher temperatures Decline in skeletal density compromises the ability of these alga to create hardground habitats in shallow‐water marine environments