The role of changing pH on olfactory success of predator–prey interactions in green shore crabs, Carcinus maenas

Arguably climate change is one of the biggest challenges faced by many organisms. One of the more significant of these is the decreasing pH level of the ocean, a consequence of the increasing amount of atmospheric CO2 being absorbed. With the current open ocean pH level of 8.15 projected to fall to just over 7.6 in 2100, the impacts could be devastating for marine species reliant upon olfaction to survive. Here, we show that Carcinus maenas (shore crab) can detect and respond to the presence of odour cues from predatory species with no significant change between both current and projected pH conditions. In contrast, C. maenas ability to detect and respond to prey cues is altered in the projected climate change conditions, with a delayed response being observed at pH 7.6. A difference can be seen between males and females, with males detecting prey cues faster than females in reduced pH, suggesting the potential for males to be better acclimated to future climate change conditions. The change in ocean chemistry is postulated to have a fundamental impact on chemical communication systems in aquatic species. Here, we show such negative impacts of altered pH on feeding responses in Carcinus maenas, a typically robust keystone intertidal species and confirm that not all behaviours are affected equally with potentially significant implications for such functional traits and species interactions.