Frequency changes in humpback whale (Megaptera novaeangliae) song units in response to small boat noise Astarte Brown Advised by Kerri D. Seger

Anthropogenic noise compromises the effectiveness of communication in marine animals. This can interfere with natural auditory signal processing (for example, “masking”). Some animals have been shown to change the frequencies of their vocalizations to avoid masking. Humpback whales produce songs with low fundamental frequencies which often overlap with the low frequency content of vessel noise. In the Gulf of Tribugá, a part of the breeding grounds for humpback whale Stock G, a marine port construction project has been proposed. If constructed, underwater noise would significantly increase and potentially cause acoustic behavioral changes, negatively impacting communication efforts among the whales. This study was supported by SURIEA, and tested whether humpback whales in the Gulf of Tribugá changed the frequency content of their songs during and after boat noise as compared to before it was present. Out of 38 comparisons, song frequencies significantly changed 9 times. Additionally, out of 20 comparisons, bandwidth narrowed 11 times, broadened 9 times, shifted higher 6 times, and shifted lower 2 times. These results give greater insight into how humpback whales are able to adjust their song structure in response to small boat noise and indicate that adaptations to some anthropogenic noise sources are possible.