title: Weakening mechanisms of the serpulid tube in a high-CO2 world.
abstract: Many benthic marine organisms produce calcium carbonate (CaCO3) structures for mechanical protection through a biologically controlled calcification process. However, the oceans are becoming unfavorable for calcification because of the stress associated with ocean acidification (OA) and associated chemical changes such as declining saturation state of CaCO3 and decreasing seawater pH. This work studies the impacts of OA-driven decreased pH on the calcareous tubes produced by the serpulid tubeworm Hydroides elegans. Tubes grown under control and OA experimental conditions were measured for structural and mechanical properties, and their mechanical properties were further interpreted using finite element analysis (FEA). The near-future predicted pH value of 7.8 altered tube ultrastructure, volume, and density and decreased the mean tube hardness and elasticity by ∼ 80 and ∼ 70%, respectively. The crushing force required for breaking the tube was reduced by 64%. The FEA results demonstrated how a simulated predator attack may affect the structure with different structural and mechanical properties and consequently shift the stress development and distribution in the tubes, causing a more concentrated stress distribution and therefore leading to a lower ability to withstand attacks.
authors.affiliation: The Swire Institute of Marine Science and School of Biological Sciences, The University of Hong Kong , Pokfulam, Hong Kong SAR.
authors.forename: Chaoyi
authors.initials: C
authors.lastname: Li
authors.forename: Vera B S
authors.initials: VB
authors.lastname: Chan
authors.forename: Chong
authors.initials: C
authors.lastname: He
authors.forename: Yuan
authors.initials: Y
authors.lastname: Meng
authors.forename: Haimin
authors.initials: H
authors.lastname: Yao
authors.forename: Kaimin
authors.initials: K
authors.lastname: Shih
authors.forename: Vengatesen
authors.initials: V
authors.lastname: Thiyagarajan
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002113:Calcification, Physiologic; D002119:Calcium Carbonate / Q000737:chemistry / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning; D011077:Polychaeta / Q000737:chemistry / Q000502:physiology* / Q000648:ultrastructure*; D012623:Seawater / Q000737:chemistry*; D055114:X-Ray Microtomography
chemical_list: D002245:Carbon Dioxide; D002119:Calcium Carbonate