Abstract

The interaction of multiple climate change stressors can affect the behavior of marine fish. While these effects have been reported in tropical and temperate species, much less is known for fish inhabiting high latitudes. We analyzed the combined effects of ocean acidification and the highest and lowest seasonal temperatures on the activity level and boldness of Eleginops maclovinus, an ecologically and commercially important notothenioid fish from the subantarctic area. Juveniles were acclimated for one month to two temperatures (T = 4 and 10 degrees C) and two pCO(2) levels (similar to 500 and similar to 1800 mu atm) in a full factorial design. In an open field test, the time spent active was significantly affected by temperature, with fish at 10 degrees C 1.63 times more active than those at 4 degrees C, but not by pCO(2) or the interaction (T x pCO(2)). No differences were observed in the average swimming velocity measured when active, nor in the time spent in the inner zone of the tank. A refuge emergence test indicated increased boldness under near-future pCO(2) levels with fish emerging 2.06 (4 degrees C) and 1.23 (10 degrees C) times faster than those acclimated to present-day pCO(2) levels. The disruptions of these fundamental behaviors by these climate-driven stressors could have consequences for foraging and predator-prey interactions, with likely detrimental effects on the interactions among sympatric subantarctic fishes under projected climate change scenarios.