Acidification effects in the behavioural responses of temperate reef fish larvae

Due to anthropogenic activity, atmospheric CO2 levels have been increasing since the last century. Consequently, the average levels of surface pH in the ocean is drastically dropping, affecting marine life, including changes in fish behaviour. In many coastal marine fish the selection of the adult habitat occurs in the pelagic larval phase, relying on hearing and olfaction for orientation as well as for predator avoidance and communication. In the present study, the effects of ocean acidification in the ability of fish larvae to detect olfactory cues from potential predators and auditory cues from adult habitats (reefs) were tested. Larvae of sand-smelt (Atherina presbyter) and painted goby (Pomatoschistus pictus) were reared in a control CO2 treatment (pH~8.10) and in a high CO2 treatment (pH~7.6). Later, fishes were subjected to odour experiments in a two channel choice flume and to sound experiments in an auditory choice chamber. Sand-smelt larvae reared in both control and acidified treatment did not show any response to olfactory cue and to reef sounds. Larval painted goby reared in high CO2 treatment and exposed to olfactory cue, strongly avoided the cue, what did not occur in larvae reared in control CO2 treatment. Regarding to sound tests, painted goby larvae from control treatment discriminated reef noises, as expected, however this behavior was absent in larvae reared in an acidified treatment. This study provid evidence that ocean acidification might affect the sensorial responses (olfactory and auditory) of larvae in some temperate reef fish, with potentially injurious impacts on their survival.

Castro J. M. P. de P. e, 2014. Acidification effects in the behavioural responses of temperate reef fish larvae. MSc thesis, Universidade de Lisboa, 66 pp. Thesis.

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