Boat noise alters individual behaviours but not communication between partners in a fish-shrimp mutualism

Abstract Persistent noise pollution produced by boat traffic is reshaping marine soundscapes globally. Despite growing ecological concern, most studies to date have focused on individual-level effects under laboratory conditions, leaving major gaps in our understanding of how boat noise shapes species interactions in the wild. Using field-based behavioural assays, we investigate how boat noise from different engine types (4-stroke and 2-stroke) affects the mutualistic partnership between Steinitz’s goby (Amblyeleotris steinitzi) and snapping shrimp (Alpheus spp.). Across 123 partnerships, we recorded behavioural responses before, during, and after noise exposure. Gobies increased burrow use during 4-stroke boat noise exposure, while shrimp responded stronger to 2-stroke noise—reflecting taxon-specific sensitivities to different noise spectra. Despite these shifts, tactile partner communication was not affected by boat noise. These findings highlight divergent vulnerabilities between species tied to different engine acoustics, and emphasise the need for targeted research to inform strategies for mitigating marine noise pollution.