Online

Gagne, Emma

Biology

2022

M.S.

Ocean soundscapes have been changing at an unprecedented rate due to the increase of human presence and associated boat noise. The physical properties of water allow sound to travel quickly with little degradation, leading to the pervasiveness and intensity of anthropogenic noise. For animals that rely on sound to communicate, this noise poses a threat to fitness and success by 'masking' their signals. As such, animals must find ways to be heard above the noise. Additionally, noisy environments have been shown to cause stress, which can have detrimental impacts on animal health. In recent years, various studies have shown that the acoustic characteristics of animal's signals provide information about their behavioral state, and thus are effective and noninvasive alternatives to study stress in animal populations. Here I studied the acoustic signals of two marine vertebrates, the bocon toadfish and bottlenose dolphin, of the archipelago of Bocas del Toro, Panama before and during widespread systematic noise reduction amid COVID-19 lockdowns. My results showed that during the lockdown, acoustic signal detection of both toadfish and dolphins increased, and changes in the acoustic characteristics of their signals are consistent with a quieter acoustic environment. In addition, for bottlenose dolphins a reduction of signal modulation suggests a decrease in stress related to tour-boat harassment. My findings shed light on how marine animals rapidly respond to changes in underwater noise levels and contribute to a better understanding of the impact of human-made noise in coastal soundscapes.