Dear Marmam readers,
The following paper has recently been published in Marine Ecology Progress
Series:
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.
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.
The paper can be accessed via: www.mucru.org
or via email requests to: Julian Tyne (j.t...@murdoch.edu.au) or Lars Bejder
(l.bej...@murdoch.edu.au)
Best,
Lars
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Lars Bejder, PhD.
Cetacean Research Unit
Centre for Fish, Fisheries and Aquatic Ecosystem Research
Murdoch University South Street Murdoch WA 6150
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