The Marine Soundscape of Port Phillip Bay—Australia’s Busiest Shipping Port

Abstract Port Phillip Bay (PPB) is a hub of trade, tourism, and biodiversity, located in the state of Victoria, along the south coast of Australia. This region facilitates the transport of ~ 1/3 of Australia’s annual container trade, provides waterscape for the state’s > 197,000 registered recreational vessels, and accommodates > 1300 species of marine flora and fauna (including the resident, critically endangered Burrunan dolphin, Tursiops australis ) within its coastal habitat. Despite its economic and ecological assets, the acoustic environment of PPB remains uncharacterised. This study presents the first assessment of key marine soundscape contributors within PPB from nine passive acoustic monitoring (PAM) stations deployed in 2021–2023. Biophony was largely attributed to snapping shrimp chorus and fish calls, with dolphin, whale, and ray vocalisations also recorded. Anthropophony associated with recreational and commercial vessels was ubiquitously identified within the soundscapes. The PAM detection range of Burrunan dolphin vocalisations was estimated for future monitoring of dolphin distribution and activity. Ambient noise levels within the species’ whistle band (5370–10,750 Hz) were assessed at each mooring location, with Burrunan dolphin detection ranges varying between sites. This study presents an integral baseline against which to monitor shifts in PPB marine soundscape composition and condition further into the Anthropocene, allowing for early detection and mitigation of acoustic threats and biophonic loss within this heavily impacted but ecologically critical marine environment.