Antagonistic effects of ocean acidification and warming on hunting sharks

Abstract

Ocean warming and acidification alter the physiological performance and behaviour of many small-bodied fishes, yet the potential interactive effects of these stressors on larger predators remains poorly understood. In particular, the combined effects of elevated temperature on metabolism and of elevated CO 2 on the behaviour of large predators may not only affect their foraging behaviour, but also the communities in which their prey live. We used a factorial design to assess how projected warming and acidification create synergies or antagonisms between physiological and behavioural processes, such as swimming activity and feeding behaviour through odour tracking and vision. Temperature increased swimming activity during feeding, independent of CO 2 . Although temperature also increased motivational drive to locate and accept prey, elevated CO 2 negated chemical and visual behavioural responses that enable effective hunting. Fundamental to these effects was the negligible effect of high CO 2 in isolation, but its power to negate the positive effects of temperature when brought in conjunction. The reduced potential to locate prey due to the interactive effects of ocean acidification and warming, in combination with increases in energetic demand, suggests that energetic tradeoffs will be needed for sharks to sustain themselves at an individual and population level in a future ocean.

Understanding interactions between plasticity, adaptation and range shifts in response to marine environmental change

“…However, predicting multi-stressor responses is difficult as a range of potential phenotypic and genotypic responses may exist depending on the combination of stressors involved (e.g. [161]). Gaining this knowledge will take an approach that combines broad-scale quantitative information on the abundances of species across space and time with both laboratory and field-based experimentation.…”

Biological responses of sharks to ocean acidification

“…This temperature effect was recurrent in other studies and is highlighted in figure 2. In a subsequent study [40], the same team revealed that although warming increased prey location rate in H. portusjacksoni, future CO 2 conditions inhibited the chemical and visual behavioural responses that allow effective hunting in the test arenas. Similarly, Dixson et al [41] found that high CO 2 -treated smooth dogfish (Mustelus canis) were less attracted to a water stream containing a food stimulus and reduced attack behaviour when compared to their control counterparts.…”

“…The physiological effects of simulated end-of-century elevated CO 2 conditions have only been evaluated in four relatively sedentary, benthic species: the temperate lesserspotted (Scyliorhinus canicula) catshark [38] and Port Jackson (H. portusjacksoni) sharks [39,40] and the tropical bamboo (C. punctatum) [32][33][34] and epaulette (H. ocellatum) sharks [35,36] (table 1). Previous studies investigating physiological processes under elevated CO 2 in sharks have been conducted at very high CO 2 levels (.8-10 mm Hg, approximately 10 000-13 000 matm) (e.g.…”

Predatory strategies and behaviours in cephalopods are altered by elevated CO2

“…Elevated CO 2 levels can have many adverse effects on marine animal physiology (P€ ortner, Langenbuch, & Reipschl€ ager, 2004), life history traits (Kroeker et al, 2013) and behaviour (Nagelkerken & Munday, 2016). Much of the research into the behavioural effects of elevated CO 2 has focused on fish (Heuer & Grosell, 2014), showing multiple adverse effects to sensory systems (Munday et al, 2009(Munday et al, , 2010Simpson et al, 2011) and influencing ecologically important behaviours, such as predator-prey interactions (Allan, Domenici, McCormick, Watson, & Munday, 2013;Cripps, Munday, & McCormick, 2011;Ferrari et al, 2011Ferrari et al, , 2015Pistevos, Nagelkerken, Rossi, & Connell, 2016;Pistevos, Nagelkerken, Rossi, Olmos, & Connell, 2015). New studies have also demonstrated the behavioural impacts of elevated CO 2 on marine molluscs.…”