Seawater carbonate chemistry and biomechanical properties of the skeletal plates of the sea urchin Paracentrotus lividus (Lamarck, 1816)

• Main Authors: Asnaghi, Valentina, Collard, Marie, Mangialajo, Luisa, Gattuso, Jean-Pierre, Dubois, Philippe
• Format: Dataset
• Language: English
• Published: PANGAEA 2023
• Subjects: Alkalinity; total; standard deviation; Animalia; Aragonite saturation state; Area; Benthic animals; Benthos; Bicarbonate ion; Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Containers and aquaria (20-1000 L or < 1 m**2); Diet; Echinodermata; Force; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Individuals; Laboratory experiment; Laboratory strains; Not applicable; OA-ICC; Ocean Acidification International Coordination Centre; Other; Other studied parameter or process; Paracentrotus lividus; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; Plate; Salinity; Single species; Species; unique identification; unique identification (Semantic URI); unique identification (URI); Temperature; water; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.960351; https://doi.org/10.1594/PANGAEA.960351

Sea urchins, ecologically important herbivores of shallow subtidal temperate reefs, are considered particularly threatened in a future ocean acidification scenario, since their carbonate structures (skeleton and grazing apparatus) are made up of the very soluble high-magnesium calcite, particularly sensitive to a decrease in pH. The biomechanical properties of their skeletal structures are of great importance for their individual fitness, because the skeleton provides the means for locomotion, grazing and protection from predators. Sea urchin skeleton is composed of discrete calcite plates attached to each other at sutures by organic ligaments. The present study addressed the fate of the sea urchin Paracentrotus lividus (Lamarck, 1816) skeleton in acidified oceans, taking into account the combined effect of reduced pH and macroalgal diet, with potential cascading consequences at the ecosystem level. A breaking test on individual plates of juvenile specimens fed different macroalgal diets has been performed, teasing apart plate strength and stiffness from general robustness. Results showed no direct short-term effect of a decrease in seawater pH nor of the macroalgal diet on single plate mechanical properties. Nevertheless, results from apical plates, the ones presumably formed during the experimental period, provided an indication of a possible diet-mediated response, with sea urchins fed the more calcified macroalga sustaining higher forces before breakage than the one fed the non-calcified algae. This, on the long term, may produce bottom-up effects on sea urchins, leading to potential shifts in the ecosystem equilibrium under an ocean acidified scenario.