What's That You Say? Fish Can Hear Better in High-CO2 Water?
Bignami, S., Enochs, I.C., Manzello, D.P., Sponaugle, S. and Cowen, R.K. 2013. Ocean acidification alters the otoliths of a pantropical fish species with implications for sensory function. Proceedings of the National Academy of Sciences USA 110: 7366-7370.
At an atmospheric partial pressure of 2100 ppm CO2, there was a significant increase in otolith size (up to 49% greater volume and 58% greater relative mass), as well as a 6% increase in otolith density, while the estimated relative mass of larval cobia otoliths in an end-of-century 800 ppm CO2 treatment was 14% greater.
Armed with these experimental observations, Bignami et al. go on to demonstrate that "these changes could affect auditory sensitivity including a ~50% increase in hearing range at 2100 ppm CO2." And they say that "this is a potentially optimistic result, indicating some resistance to acidification and suggesting that under near-future scenarios these impacts may be most relevant in habitats already experiencing high pCO2 levels."
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