Pile driving noise hinders growth in marine bivalve

Offshore wind is a key renewable resource increasingly relied upon to meet growing energy needs. Pile driving, widely used for offshore windfarm construction, produces intense, impulsive sounds. These signals can cause short-term changes in the physiology and behavior of marine organisms, such as repeated valve closures in the sea scallop (Placopecten magellanicus); however, far less is known regarding how longer exposures may impact vital growth and development. We performed controlled laboratory experiments exposing juvenile sea scallops to daily playbacks of pile driving impulses to examine how these signals may influence behavior and growth over a month-long period. Pile driving playback reached peak sound pressure levels up to 172 dB re 1 µPa in this tank setup. Integrated, miniature biologging movement tags recorded behavioral reactions in both the pile driving and control tanks for a subset of animals. Scallop volume metrics were significantly lower in the pile driving playback treatments than control groups, suggesting growth impacts. Overall, these results suggest that scallop fitness is negatively affected by chronic noise exposure, perhaps due to unhabituated, repeated closing behaviors observed in short-term experiments. Such prolonged exposures and responses were detrimental to growth and underscore potential implications for pile driving in key scallop fishery areas.