Predator sound playbacks also had consequences for circulating stress hormones, as cortisol levels were significantly elevated in male toadfish exposed to dolphin pops compared with snapping shrimp pops. High frequency dolphin sounds (whistles) and low-frequency snapping shrimp pops (ambient control sounds) each had no effect on toadfish calling rates. Using underwater playbacks to toadfish in their natural environment, we found that low-frequency dolphin sounds ( pops') within the toadfish's range of hearing dramatically reduce toadfish calling rates by 50%. Here, we used both behavioral (vocalizations) and physiological (plasma cortisol levels) parameters to determine if male Gulf toadfish can, in turn, detect the acoustic signals of bottlenose dolphins. In addition, soniferous fishes constitute over 80% of Tursiops diet, and toadfishes alone account for approximately 13% of the stomach contents of adult bottlenose dolphins. Previous work showed that bottlenose dolphins (Tursiops truncatus) behaviorally orient toward the sounds of prey, including the advertisement calls of male Gulf toadfish (Opsanus beta). This project is currently in the early stages with opportunistic sound recordings being made during our Moreton Bay Dolphin Research Expeditions with our Eco-Volunteer teams.The passive listening hypothesis proposes that dolphins and whales detect acoustic signals emitted by prey, including sound-producing (soniferous) fishes. These results will be compared with the Indo-Pacific bottlenose dolphins which live sympatrically with humpback dolphins. It’ll examine the vocal repertoire of humpback dolphins in Moreton Bay, how variable acoustic emissions are during different behavioural contexts, variations between social groups and how different soundscapes may influence their communication. This project will provide insight into the acoustic communication systems of these vulnerable animals. Little is known about the acoustic communication systems of the Australian humpback dolphin. Listen to Dolphinsīottlenose dolphin chasing fish chasing fish1īottlenose dolphin whistling contact callsaĪustralian Humpback Dolphin & Indo-Pacific Bottlenose Dolphin Acoustic Communication We believe that the development and use of this equipment will drastically improve the techniques used to record dolphin behaviour and acoustics which have previously been very limiting.įindings from this study will advance the understanding of ecological requirements of these highly social marine mammals that rely on their acoustic communication to survive. This study involves an international team of leading researchers. Innovative and technologically advanced equipment will be developed to obtain recordings of concurrent underwater and directional sound recordings. This study will examine the types of acoustic emissions produced by coastal dolphins and investigate the functions of these sounds. Little is know about the specific functions and ecological significance of these complex sounds produced by dolphins. Most species of dolphins produce a large variety of acoustic signals that are generally categorised as whistles, clicks and broad band signals. They are particularly reliant on their acoustic communication faculty to effectively and efficiently hunt, navigate, maintain contact between group members and advertise individual identity and activity. Dolphins have a complex and intricate visual, acoustic and chemical communication system.
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