Effect on marine animals
- Ocean Acidification could impact many ocean animals (both adults and larvae), especially bivalves and mollusks that use calcium carbonate for their exoskeletons
- Ocean acidification also promotes the dissolution of coccolithophores (picture below) and foraminifera, which constitute 30% and 20-50% of marine calcium carbonate production (e.g., Riebesell et al., 2000; Langer et al., 2006; Iglesias-Rodriguez et al., 2008; Kohbeck et al., 2012; Beaufort et al., 2015)
- Ocean acidification affects coral reef development and diversity (e.g., Langdon et al., 2000; Fabricius et al., 2011), likely by increasing the energy cost required to pump protons out of the polyps (Cohen and Holcomb, 2009) and decreasing the bleaching temperature threshold (Anthony et al., 2008)
- Ocean acidification also affects animals indirectly. For example, acidification prevents fish to smell chemical signals or hear sounds they use to find their way around habitats which may affect their predation (Munday et al., 2009; Simpson et al., 2011)
Effect on Marine Phytoplankton
- The increase in atmospheric CO2 also stimulates primary production or phytoplankton growth.
- Diatoms and cyanobacteria, two of the most important CO2 fixing phytoplankton in the oceans, are directly stimulated by increase in CO2 (e.g., Riebesell et al., 2007; Kranz et al., 2011; Wannike et al., 2012; Hutchins et al., 2013)
- Although primary production is stimulated by CO2 increases, the distribution of species is most affected with poorly understood effects on biodiversity and ecosystem function (Riebesell et al., 2007)
- At low pH, primary production decreases (Hinga, 2002), likely because enzymatic processes are affected (e.g., Shi et al., 2012)
- Increasing phytoplankton growth may help fixing CO2 from the atmosphere. However, phytoplankton eventually dies and is degraded in the deep waters, which promotes oxygen consumption and may lead to hypoxia in certain conditions.