Temperate fish show behavioural robustness to near-future carbon dioxide levels (#433)
The dramatic anthropogenic release of carbon dioxide is altering the composition of the atmosphere and also the dissolved gases in the sea in a process termed ocean acidification. Compared to current day levels, the levels of dissolved CO2 may more than double in the oceans by the year 2100, according to IPCC. Although a relatively new research area, major effects of elevated CO2 levels on marine organisms are emerging. However, the effects on adult temperate fish are still poorly known, as the research focus to date has been on the larval stages, and further mainly on coral reef fish. Through a series of controlled laboratory experiments, using automated behaviour analysis systems, we investigated the possible impact of increased levels of carbon dioxide on reproductive behaviours, olfactory cue preferences, and activity. As model species we used goldsinny wrasse, two-spotted goby, and three-spined stickleback. Interestingly, we found that all species were surprisingly robust to CO2 exposure, with few effects detected on the behaviours investigated. Thus, in this comprehensive study, thoroughly investigating behaviours where adverse effects of CO2 have previously been reported in other species of fish, we failed to detect major effects of carbon dioxide in most behaviours, with some notable exceptions. We show that individual fish can show disturbance in specific behaviours while at the same time being apparently unaffected by elevated CO2 in other behavioural tests. The interspecific variation in susceptibility demonstrates that we are far from able to predict possible future impacts of ocean acidification on marine fishes and ecosystems.