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Marine Ecology Progress Series

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MEPS 444:143-153 (2012)  -  DOI:

Ecological characteristics contribute to sponge distribution and tool use in bottlenose dolphins Tursiops sp.

Julian A. Tyne1,*, Neil R. Loneragan1, Anna M. Kopps2,3, Simon J. Allen1, Michael Krützen1,2,3, Lars Bejder1

1Murdoch University Cetacean Research Unit, Centre for Fish, Fisheries and Aquatic Ecosystem Research, School of Biological Sciences and Biotechnology, Murdoch University, South Street, Murdoch, Western Australia 6150, Australia
2Evolution & Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, New South Wales 2052, Australia
3Evolutionary Genetics Groups, Anthropological Institute and Museum, University of Zurich, Winterthurerstr. 190, 8057 Zurich, Switzerland

ABSTRACT: In Shark Bay, Western Australia, bottlenose dolphins Tursiops sp. carry conical sponges Echinodictyum mesenterinum on their rostra in the only documented cetacean foraging behaviour using a tool (‘sponging’). In this study, we examined the influence of various ecological factors on live sponge distribution and the occurrence of sponging in parts of the western gulf of Shark Bay. We assessed sponge distribution and seagrass cover along 12 transects of approximately 11 km length, by recording sponges and seagrass in a total of 1380 quadrats (1 × 1 m), of which 56 quadrats contained conical sponges. The occurrence of sponging dolphins (‘spongers’) was documented along 10 of these 12 transects. The distribution of conical sponges was negatively correlated with the distribution of seagrass: no conical sponges were observed in water depths of <10 m and no seagrasses were found at depths of >12 m. A digital elevation model, created from the sample depth data, identified channels in the region. Binary logistic and Poisson log-linear generalised linear models showed that water depth and bathymetric features including channel, substrate and slope were significant in predicting the occurrence and the mean number of conical sponges, as well as that of seagrass. Conical sponge distribution was positively correlated with the distribution of sponging, indicating that ecological factors influence where sponging occurs. The greater number of spongers found in this region may be explained by the larger area of habitat suitable for conical sponges in the western than the eastern gulf of Shark Bay.

KEY WORDS: Dolphin behaviour · Social transmission · Digital elevation model · Bathymetry · Shark Bay · Western Australia

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Cite this article as: Tyne JA, Loneragan NR, Kopps AM, Allen SJ, Krützen M, Bejder L (2012) Ecological characteristics contribute to sponge distribution and tool use in bottlenose dolphins Tursiops sp.. Mar Ecol Prog Ser 444:143-153.

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