Will Burning Fossil Fuels Reduce Baltic Cod Reproduction Rates?
Frommel, A.Y., Stiebens, V., Clemmesen, C. and Havenhand, J. 2010. Effect of ocean acidification on marine fish sperm (Baltic cod: Gadus morhua). Biogeosciences 7: 3915-3919.
To explore this subject further, the four researchers collected sperm from ripe adult male cod fish (Gadus morhua, that they had caught during an August cruise through their spawning grounds in the Baltic Sea's Bornholm Basin), which they exposed to seawater that had been brought into equilibrium (by bubbling) with air of either 380 or 1400 ppm CO2 (leading to seawater pH values of 8.080 and 7.558, respectively), during which exposure period sperm swimming behavior was recorded using a digital camera. So what did they learn?
In the words of the scientists who conducted the experiment, "we found no significant effect of decreased pH on sperm speed, rate of change of direction or percent motility for the population of cod analyzed." In light of their careful and meticulous observations, Frommel et al. conclude that "future ocean acidification will probably not pose a problem for sperm behavior, and hence fertilization success, of Baltic cod."
Westin, L. and Nissling, A. 1991. Effects of salinity on spermatozoa motility, percentage of fertilized-eggs and egg development of Baltic cod (Gadus morhua), and implications for cod stock fluctuations in the Baltic. Marine Biology 108: 5-9.