CO 2 -induced ocean acidification does not affect individual or group behaviour in a temperate damselfish

• Published in: Royal Society Open Science
• Main Authors: Kwan, Garfield Tsz, Hamilton, Trevor James, Tresguerres, Martin
• Other Authors: Natural Sciences and Engineering Research Council of Canada, Division of Graduate Education, Division of Emerging Frontiers, University of California San Diego, Alfred P. Sloan Foundation
• Format: Article in Journal/Newspaper
• Language: English
• Published: The Royal Society 2017
• Subjects: Ocean acidification
• Online Access: http://dx.doi.org/10.1098/rsos.170283; https://royalsocietypublishing.org/doi/pdf/10.1098/rsos.170283; https://royalsocietypublishing.org/doi/full-xml/10.1098/rsos.170283

Open ocean surface CO 2 levels are projected to reach approximately 800 µatm, and ocean pH to decrease by approximately 0.3 units by the year 2100 due to anthropogenic CO 2 emissions and the subsequent process of ocean acidification (OA). When exposed to these CO 2 /pH values, several fish species display abnormal behaviour in laboratory tests, an effect proposed to be linked to altered neuronal GABA A­ receptor function. Juvenile blacksmith ( Chromis punctipinnis ) are social fish that regularly experience CO 2 /pH fluctuations through kelp forest diurnal primary production and upwelling events, so we hypothesized that they might be resilient to OA. Blacksmiths were exposed to control conditions (pH ∼ 7.92; p CO 2 ∼ 540 µatm), constant acidification (pH ∼ 7.71; p CO 2 ∼ 921 µatm) and oscillating acidification (pH ∼ 7.91, p CO 2 ∼ 560 µatm (day), pH ∼ 7.70, p CO 2 ∼ 955 µatm (night)), and caught and tested in two seasons of the year when the ocean temperature was different: winter (16.5 ± 0.1°C) and summer (23.1 ± 0.1°C). Neither constant nor oscillating CO 2 -induced acidification affected blacksmith individual light/dark preference, inter-individual distance in a shoal or the shoal's response to a novel object, suggesting that blacksmiths are tolerant to projected future OA conditions. However, blacksmiths tested during the winter demonstrated significantly higher dark preference in the individual light/dark preference test, thus confirming season and/or water temperature as relevant factors to consider in behavioural tests.