Publication Date:
2024-03-15
Description:
The current increase in atmospheric CO2 concentration induces changes in the seawater carbonate system resulting in decreased pH and calcium carbonate saturation state, a phenomenon called ocean acidification (OA). OA has long been considered as a major threat to echinoderms because their extensive endoskeleton is made of high‑magnesium calcite, one of the most soluble forms of calcium carbonate. Numerous studies addressed this question in sea urchins, but very few questioned the impact of OA on the sea star skeleton, although members of this taxon do not compensate their extracellular pH, contrary to most sea urchins. In the present study, adults of the common sea star, Asterias rubens from Kiel Fjord, a site experiencing natural acidification events exceeding pCO2 levels of 2500 μatm, were chronically exposed to different levels of simulated ocean acidification (pHT-SW 8.0, 7.4, 7.2), encompassing present and future conditions, for the duration of 109 days. Corrosion and mechanical properties of skeletal elements were studied using scanning electron microscopy, three-point bending tests as well as nanoindentation. The spines were significantly corroded at pHT-SW 7.4 and below while the ambulacral plates were only affected at pHT-SW 7.2. Nanoindentation of newly formed spines and ambulacral plates did not reveal significant CO2-induced differences in skeleton hardness or elasticity across treatments. Results of three-point bending tests revealed significantly reduced characteristic strength and fracture force of ambulacral plates from the median arm segment at pHT-SW 7.4 and below. These plates are those supporting the tube feet involved in the opening of bivalves during feeding and in the animal attachment to the substrate. Under reduced seawater pH, this might result in fracture of sea star plates during predation on mussel. The present results predict a possible impact of ocean acidification on the skeletal integrity of a marine keystone predator.
Keywords:
Alkalinity, total; Alkalinity, total, standard deviation; Animalia; Aragonite saturation state; Aragonite saturation state, standard deviation; Baltic Sea; Benthic animals; Benthos; Bicarbonate ion; Bicarbonate ion, standard deviation; Bottles or small containers/Aquaria (〈20 L); Calcite saturation state; Calcite saturation state, standard deviation; Calculated using seacarb after Nisumaa et al. (2010); Calculated using seacarb after Orr et al. (2018); Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard deviation; Carbonate ion; Carbonate ion, standard deviation; Carbonate system computation flag; Carbon dioxide; Carbon dioxide, standard deviation; Coast and continental shelf; Corrosion; Corrosion, standard deviation; Displacement; Echinodermata; EXP; Experiment; Force; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Fugacity of carbon dioxide in seawater, standard deviation; Growth/Morphology; Hardness; Hardness, standard deviation; Identification; Kiel_OA; Laboratory experiment; Length; Magnesium carbonate; Magnesium carbonate, standard deviation; OA-ICC; Ocean Acidification International Coordination Centre; Other studied parameter or process; Partial pressure of carbon dioxide, standard deviation; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; pH, standard deviation; Position; Pressure, stress; Registration number of species; Replicate; Salinity; Salinity, standard deviation; Second moment of area; Segment of arm; Single species; Species; Temperate; Temperature, water; Temperature, water, standard deviation; Treatment; Type; Uniform resource locator/link to reference; Young's modulus; Youngs modulus, standard deviation
Type:
Dataset
Format:
text/tab-separated-values, 19579 data points
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