Title and publication details:
Tyne J.A, Loneragan N.R, Kopps A.M, Allen S.J, Krützen M and Bejder L. 2012. Ecological characteristics contribute to sponge distribution and tool use in bottlenose dolphins Tursiops sp. Marine Ecology Progress Series 444:143-153.
Bottlenose dolphins (Tursiops sp.) in the eastern gulf of Shark Bay, Western Australia, have been studied for nearly 30 years. During this period, it was documented that some dolphins carry conical shaped sponges (Echinodictyum mesenterinum), on their rostra, a behaviour termed ‘Sponging’. Sponging was subsequently documented as the first cetacean foraging behaviour using a tool. The sponges are thought to afford the rostra protection while foraging in the substratum.
Recent studies have shown Sponging is passed from mother to offspring, a pattern found in both the eastern and western gulfs of Shark Bay. However, previous studies did not investigate how ecological factors might affect this behaviour. In this paper, we investigated the relationship between ecological variables that influence sponge distribution, and the distribution of bottlenose dolphins that exhibit Sponging (Spongers) and those that do not (Non-Spongers).
Here, we show that water depth and bathymetric features influence the distribution of conical sponges, which, in turn is influential in predicting the distribution of spongers. This indicates that ecological factors influence where sponging occurs in the western gulf of Shark Bay. Moreover, we documented a larger number of sponging dolphins in the western gulf during a three-year period, compared to that in the eastern gulf during nearly 30 years of study. This indicates that the western gulf area is more ecologically favourable to sponging than that in the eastern gulf.
This study was a collaboration between Murdoch University, University of Zurich and the University of New South Wales.