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Title: The taphonomy of giants: whale-falls and the bioerosion of whale skeletons
Author: Higgs, Nicholas Dawson
ISNI:       0000 0004 2746 1763
Awarding Body: University of Leeds
Current Institution: University of Leeds
Date of Award: 2012
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In the last two decades a series of chance discoveries and dedicated research programmes have produced a wealth of data on the post-mortem fate of whale carcasses. Biological taphonomic processes at whale skeletons on the seafloor are driven by chemical energy in the form of abundant lipid reserves in whale skeletons. Previously unrecognised variations in the lipid content of bones from different parts of whale skeletons explained patterns of faunal colonisation and bone degradation. Experimental work to elucidate the mechanisms responsible for these relationships demonstrated that the breakdown of bone lipids retards. microbial digestion of the bones, leading to differential degradation of the skeleton. Furthermore, analysis of total skeletal lipid content shows that when this value is high «1000 kg) skeletons may last for decades on the seabed until degradation or burial leading to a taphonomic bias towards large mature individuals. Another key factor in determining the longevity of whale skeletons on the seafloor is the activity of Osedax tubeworms, which bore into the bones, using them as a source of nutrition. Micro computed-tomography was used to investigate multiple aspects of bone destruction by Osedax. Rates of bone erosion by Osedax mucofloris in experimentally deployed bones varied between 1-6% per year, depending on the density of colonisation. The boring morphology of thirteen Osedax species were quantitatively described and analysed. Most species preferentially utilise the collagen matrix of the bone through the erosion of individual bone trabeculae, indicating that bone structure is largely responsible for the boring morphology. Using this information Osedax borings were described in a fossil whale bone from shelf-depth sediments from the Pliocene of Italy, indicating that by this time Osedax was widespread throughout the world's oceans. Further evidence of Osedax bioerosion in samples from the abyssal Pacific suggests that these worms probably have a worldwide distribution today.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available