Ocean acidification impacts on sperm mitochondrial membrane potential bring sperm swimming behaviour near its tipping point

• Main Authors: Schlegel, Peter, Binet, Monique T, Havenhand, Jonathan N, Doyle, Christopher J, Williamson, Jane E
• Format: Dataset
• Language: English
• Published: PANGAEA 2015
• Subjects: Alkalinity; total; standard error; Animalia; Aragonite saturation state; Behaviour; Benthic animals; Benthos; Bicarbonate ion; Bottles or small containers/Aquaria (<20 L); Calcite saturation state; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Centrostephanus rodgersii; Coast and continental shelf; Echinodermata; EXP; Experiment; Fairlight_OA; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Identification; Laboratory experiment; Mitochondrial activity; Motile sperm; speed; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Percentage; pH; Potentiometric; Potentiometric titration; Reproduction; Salinity; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.848011; https://doi.org/10.1594/PANGAEA.848011

Broadcast spawning marine invertebrates are susceptible to environmental stressors such as climate change, as their reproduction depends on the successful meeting and fertilization of gametes in the water column. Under near-future scenarios of ocean acidification, the swimming behaviour of marine invertebrate sperm is altered. We tested whether this was due to changes in sperm mitochondrial activity by investigating the effects of ocean acidification on sperm metabolism and swimming behaviour in the sea urchin Centrostephanus rodgersii. We used a fluorescent molecular probe (JC-1) and flow cytometry to visualize mitochondrial activity (measured as change in mitochondrial membrane potential, MMP). Sperm MMP was significantly reduced in delta pH -0.3 (35% reduction) and delta pH -0.5 (48% reduction) treatments, whereas sperm swimming behaviour was less sensitive with only slight changes (up to 11% decrease) observed overall. There was significant inter-individual variability in responses of sperm swimming behaviour and MMP to acidified seawater. We suggest it is likely that sperm exposed to these changes in pH are close to their tipping point in terms of physiological tolerance to acidity. Importantly, substantial inter-individual variation in responses of sperm swimming to ocean acidification may increase the scope for selection of resilient phenotypes, which, if heritable, could provide a basis for adaptation to future ocean acidification.