Plasticity in organic composition maintains biomechanical performance in shells of juvenile scallops exposed to altered temperature and pH conditions Lagos, Nelson A. Grenier Romero, Cristian Rodríguez Navarro, Alejandro This study was funded by PIA ANID ACT 172037 for international collaborative research among Chile (NAL, MAL, JV, CG-H, CD) and Spain (ARN, CG). Author also acknowledges support from Fondecyt 1190444 (MAL), Fondecyt 1210171 (CAV) and ANID - Millennium Science Initiative Program - ICN2019_015 (SECOS) (NAL, MAL and CAV). ANID doctoral scholarhip #21210012 to SB. ANID PFCHA / Doctorados Becas Chile Chile/2019-CEL00011051 to AA-O and DICYT from USACH to AA-O and CG-H during the execution of sample processing and analysis. We also acknowledge to Anita Quiroga, Jhonny Rojas for their support in lab procedures, and the staff at BIO-CT Lab (Universidad de Chile). We are grateful to B. Broitman and two anonymous reviewers who provided valuable comments on previous version of the manuscript. The exposure to environmental variations in pH and temperature has proven impacts on benthic ectotherms calcifiers, as evidenced by tradeoffs between physiological processes. However, how these stressors affect structure and functionality of mollusk shells has received less attention. Episodic events of upwelling of deep cold and low pH waters are well documented in eastern boundary systems and may be stressful to mollusks, impairing both physiological and biomechanical performance. These events are projected to become more intense, and extensive in time with ongoing global warming. In this study, we evaluate the independent and interactive effects of temperature and pH on the biomineral and biomechanical properties of Argopecten purpuratus scallop shells. Total organic matter in the shell mineral increased under reduced pH (~ 7.7) and control conditions (pH ~ 8.0). The periostracum layer coating the outer shell surface showed increased protein content under low pH conditions but decreasing sulfate and polysaccharides content. Reduced pH negatively impacts shell density and increases the disorder in the orientation of calcite crystals. At elevated temperatures (18 °C), shell microhardness increased. Other biomechanical properties were not affected by pH/ temperature treatments. Thus, under a reduction of 0.3 pH units and low temperature, the response of A. purpuratus was a tradeoff among organic compounds (biopolymer plasticity), density, and crystal organization (mineral plasticity) to maintain shell biomechanical performance, while increased temperature ameliorated the impacts on shell hardness. Biopolymer plasticity was associated with ecophysiological performance, indicating that, under the influence of natural fluctuations in pH and temperature, energetic constraints might be critical in modulating the long-term sustainability of this compensatory mechanism. 2022-01-26T13:12:40Z 2022-01-26T13:12:40Z 2021-12-17 journal article Lagos, N.A... [et al.]. Plasticity in organic composition maintains biomechanical performance in shells of juvenile scallops exposed to altered temperature and pH conditions. Sci Rep 11, 24201 (2021). [https://doi.org/10.1038/s41598-021-03532-0] http://hdl.handle.net/10481/72502 10.1038/s41598-021-03532-0 eng http://creativecommons.org/licenses/by/3.0/es/ open access Atribución 3.0 España Nature