Doctoral Defense in Biology - Anna Selbmann

Doctoral candidate:
Anna Selbmann

Title of thesis:
The role of acoustic signals in interactions within and between species of cetaceans

Opponents:
Dr. Skúli Skúlason, Professor at the Department of Aquaculture and Fish Biology, Hólar University
Dr. Harald Yurk, Adjunct Professor at the School of Environmental Science, Simon Fraser University, Canada

Advisor:
Dr. Arnar Pálsson, Professor at the Faculty of Life and Environmental Sciences, University of Iceland

Other members of the doctoral committee:
Dr. Filipa I. P. Samarra, Director of the University of Iceland Research Centre in Vestmannaeyjar, University of Iceland
Dr. Paul Wensveen, Research Specialist at the University of Iceland Research Centre in Vestmannaeyjar, University of Iceland
Dr. Jörundur Svavarsson, Professor emeritus at the Faculty of Life and Environmental Sciences, University of Iceland

Chair of Ceremony:
Dr. Snæbjörn Pálsson, Professor and Head of the Faculty of Life and Environmental Sciences, University of Iceland

Abstract:
Sound is an important mode for communication and mediates a variety of interactions within and between species. Sociality is thought to promote complexity in communication systems. Cetaceans are highly vocal and social and thus provide excellent models to study acoustic communication. This thesis aimed to investigate the role of acoustic signals in mediating interactions within and between species by examining the acoustic communication of Icelandic killer whales (Orcinus orca), their interactions with long-finned pilot whales (Globicephala melas) and the role of acoustics within the interactions. A detailed description of the acoustic repertoire of killer whales showed that it is largely shared across locations around Iceland, but that some locations also have unique call types that are not recorded elsewhere. Specific combinations of calls occurred more often than expected by chance and were recorded from several locations and different social clusters. Interactions between long-finned pilot whales and killer whales were common whenever both species co-occurred. While varying in intensity, these interactions appeared to be antagonistic and mediated acoustically. Killer whales showed clear avoidance responses to playbacks of long-finned pilot whale sounds, marked by fast and directed movement away from the sound source, initial increases in calling rate followed by a strong decrease, and increased cohesion and alignment of group members. These results show that Icelandic killer whales have a complex acoustic communication system, and that acoustics also plays an important role in mediating interactions with long-finned pilot whales, therefore demonstrating the importance of sound to these highly social marine top predators.

About the doctoral candidate:
Anna Selbmann was born in Freiburg in Germany in 1985. She completed her bachelor’s degree in Marine Vertebrate Zoology at Bangor University, Wales in 2015, followed by a master’s degree in Biology at the University of Iceland in 2019. Her interest in bioacoustics and marine mammals led her to then start her doctoral research on killer whale acoustics and interspecific interactions with pilot whales at the University of Iceland.