The sensing of chemical information allows aquatic animals to interpret their surroundings over long distances. If the use of chemosensory information is impacted, the ability to find resources may be impaired. Anthropogenic activities directly contacting the seabed produce sediment vibrations which have the potential to affect behaviors guided by not only the vibrational modality but also other modalities such as chemical. Here, in subtidal field conditions, free-ranging hermit crabs (Pagurus acadianus) were exposed to an impulsive source directly contacting the substrate. A specific chemical cue, indicative of the availability of a gastropod shell (i.e. a new home), was used to attract crabs. Numbers of crabs arriving at the bait were monitored in noise versus control conditions. Fewer crabs congregated at the chemical cue after noise exposure; there was a significant effect of treatment (control/noise), time (before/after) and the interaction between the two. The results indicate that noise acted cross-modally by affecting a chemically guided shell searching behavior. The findings are collated with other studies here which also indicate cross-modal effects of sound and noise. Overall there is increasing evidence to suggest that the impacts of noise pollution should be tested across sensory modalities rather than uni-modally.

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