The European green crab (Carcinus maenas) is an intertidal crustacean that has extended its invasive range globally and is regarded as a major pest species for bivalves, impacting coastal food chains and aquacultures. Crabs primarily use chemosensory cues to sense their environment for feeding to avoid predation and to locate mates and induce mating. Consequently, known attractants including food baits are frequently employed in trapping and control efforts. Here, we investigate the effects of introducing a predatory fish odour to the environment and show that it elicits anti-predator behaviour in C. maenas. A 45% reduction in crab foraging and feeding behaviour was observed when predator odour was introduced compared with food control experiments. A further 23% reduction (68% reduction overall) in feeding behaviour was observed after crabs were exposed to (though housed separately from) the same seawater as the live predator for several days. This highlights the increased awareness or continuous stress of these habituated crabs towards predator odour. This study also presents potential for application as a deterrent in integrated pest management strategies for this global invader.

The expansion of the offshore wind industry is essential to meet global targets for reducing carbon emissions. Offshore wind infrastructure is commonly installed by pile driving, which generates high levels of water-borne and substrate-borne vibrations, known to negatively impact fish, mammals, and some marine invertebrates. This laboratory study investigates the physiological responses of the common hermit crab, Pagurus bernhardus, to levels of substrate-borne vibration likely to occur within the zone of influence of an active pile driver. Individuals were exposed to 10 ms⁻² (peak-to-peak) for 3 hours using an experimental pile driver. Oxygen consumption, tissue glucose, lactate, and protein were assessed. Hermit crabs did not significantly respond to impulsive vibration in any measures tested, suggesting that they were not impacted by vibration at this level over a 3-hour period. Despite this, further work is required to determine the impact at larger vibration levels for an extended period, which would be more reflective of pile driving operations. This is particularly important for species that may not be so well-adapted to short-term stress, as well as those with commercial and ecological importance.