How does rising atmospheric CO2 affect marine organisms?

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Impact of Heat on the Swimming Speed of a Common Damselfish

Paper Reviewed
Beyan, C., Boom, B.J., Liefhebber, J.M.P., Shao, K.-T. and Fisher, R.B. 2015. Natural swimming speed of Dascyllus reticulatus increases with water temperature. ICES Journal of Marine Science 72: 2506-2511.

Whereas almost all prior studies of fish swimming speeds had been conducted in large fish tanks housed in laboratories, Beyan et al. (2015) investigated the relationship that exists between water temperature and the swimming speed of a common damselfish (Dascyllus reticulatus) in a more natural setting, i.e., the open sea at the intake bay of a nuclear power plant at the southern tip of Taiwan that is home to that country's largest coral reef ecosystem, where they obtained almost a year's worth of fish swimming speed data by tracking individual damselfish through consecutive video frames they obtained of them and converting their image speeds to scene speeds.

This feat was accomplished at a variety of different water temperatures by analyzing some 3.6 million individual fish trajectories. And what did this monumental effort ultimately reveal?

The five researchers report there was an approximate two millimeters per second increase in average damselfish swimming speed for each 1°C increase in water temperature over the 20.9-30.3°C range of temperatures experienced at their study site over the one-year length of their study, with the highest mean swimming speed occurring over the uppermost 28.146-30.281°C temperature interval.

Out in the real world of nature, it would thus appear that potential increases in global water temperatures would likely lead to concomitant increases in damselfish swimming speeds -- and probably those of other species as well -- in contradiction of the earlier findings of several "tank-in-the-laboratory" studies, such as those conducted by Johansen and Jones (2011) and Johansen et al. (2014), for nothing beats real-world observations. And this being the case, it is also likely that many, if not most, of Earth's fish may be able to survive whatever degree of warming might possibly occur in Earth's near future.

Johansen, J.L. and Jones, G.P. 2011. Increasing ocean temperature reduces the metabolic performance and swimming ability of coral reef damselfishes. Global Change Biology 17: 2971-2979.

Johansen, J.L., Messmer, V., Coker, D.J., Hoey, A.S. and Pratchett, M.S. 2014. Increasing ocean temperatures reduce activity patterns of a large commercially important coral reef fish. Global Change Biology 20: 1067-1074.

Posted 17 May 2016