Supplementary material from "Ocean acidification alters predator behaviour and reduces predation rate"

Ocean acidification poses a range of threats to marine invertebrates; however, the emerging and likely widespread effects of rising carbon dioxide (CO₂) levels on marine invertebrate behaviour are still little understood. Here, we show that ocean acidification alters and impairs key ecological behaviours of the predatory cone snail Conus marmoreus. Projected near-future seawater CO₂ levels (975 µatm) increased activity in this coral reef molluscivore more than threefold (from less than 4 to more than 12 mm.min⁻¹) and decreased the time spent buried to less than one-third when compared with the present-day control conditions (385 µatm). Despite increasing activity, elevated CO₂ reduced predation rate during predator–prey interactions with control-treated humpbacked conch, Gibberulus gibberulus gibbosus; 60% of control predators successfully captured and consumed their prey, compared with only 10% of elevated CO₂ predators. The alteration of key ecological behaviours of predatory invertebrates by near-future ocean acidification could have potentially far-reaching implications for predator–prey interactions and trophic dynamics in marine ecosystems. Combined evidence that the behaviours of both species in this predator–prey relationship are altered by elevated CO₂ suggests food web interactions and ecosystem structure will become increasingly difficult to predict as ocean acidification advances over coming decades.