Noise exposure and acoustic behavior of beluga whales (Delphinapterus leucas) in an outdoor exhibit

Marine mammals are exposed to a wide variety of noise sources on a daily basis both in the wild and at zoos and aquaria. Filtration systems, aquarium visitors, and other anthropogenic sound sources (construction, road noise, weather, etc.) add noise to typically reverberant animal habitats in aquariums and zoos. Despite widespread concern about the effects of noise on behavior and welfare of wild marine mammals, there has been little research on the effects of chronic noise exposure on whales. This study used a single hydrophone system to characterize the acoustic environment, including noise and beluga whale vocalizations, in the Arctic Coast exhibit at Mystic Aquarium, a Division of Sea Research Foundation, Inc. between 28 October and 16 November 2010. Diel patterns in noise and beluga vocalizations, overlaps in call and noise frequencies, and general behavioral patterns were studied. Spatial variation in exhibit noise was also examined. Whale vocalizations had a distinct diel pattern, including changes in call rate and types during day and nighttime hours. Variations in noise levels were often associated with discrete events, including cleaning dives, filter backwash, and other exhibit maintenance.