Finding a home in the noise: cross-modal impact of anthropogenic vibration on animal search behaviour

Chemical cues and signals enable animals to sense their surroundings over vast distances and find key resources, like food and shelter. However, the use of chemosensory information may be impaired in aquatic habitats by anthropogenic activities, which produce both water-borne sounds and substrate-borne vibrations, potentially affecting not only vibroacoustic sensing but other modalities as well. We attracted marine hermit crabs (Pagurus acadianus) in field experiments using a chemical cue indicative of a newly available shell home. We then quantified the number of crabs arriving in control versus impulsive noise conditions. Treatment (control or noise), time (before or after), and the interaction between the two significantly affected the numbers of crabs, with fewer crabs attracted to the chemical cue after noise exposure. The results indicate that noise can affect chemical information use in the marine environment, acting cross-modally to impact chemically-guided search behaviour in free-ranging animals. Broadly, anthropogenic noise and seabed vibration may have profound effects, even on behaviours mediated by other sensory modalities. Hence, the impact of noise should be investigated not only within, but also across sensory modalities. This article has an associated First Person interview with the first author of the paper.