The decomposition of animal remains in caves

Macdonald, J., 1992. The decomposition of animal remains in caves. PhD, Nottingham Polytechnic.

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Abstract

The aim of this research, carried out at Creswell Crags, Derbyshire, was to investigate the decomposition of small mammal remains in temperate caves, with particular regard to the impact upon the cavernicolous invertebrate community and the cave sediments. The carcasses of laboratory rats were deposited in the threshold, deep threshold and hypogean regions of two caves, on sediments of differing depths layered with markers to assess the extent of bioturbation. Carcasses were covered by wire mesh to exclude vertebrate scavengers. The physical condition of the carcasses, the succession of the carrion community and the diversity of the cavernicolous invertebrates were monitored for a minimum of one year. To investigate the effect of season on decomposition, experiments were begun in both summer and winter. The processes of decomposition observed in this investigation differed considerably from those reported by other authors working on carrion deposited above ground or buried. This is especially true of the rate of carrion consumption by invertebrates which is strongly influenced by abiotic conditions. In the caves, carcasses persisted for much longer than on the surface. Carcasses in the threshold region were rapidly colonised by necrophagous Diptera, whilst the decomposition of those farther underground was initially microbial. The diversity and evenness of the invertebrate community in the threshold region were disrupted by the influx of non-cavernicolous species. In the hypogean region, the over-representation of certain troglophilic species changed the structure of the invertebrate community. These results have been incorporated into a descriptive model, which proposes decomposition pathways for small mammal carrion deposited in the threshold, deep threshold and hypogean region of shallow temperate caves. The activity of arthropods, particulary dipterous larvae, was found to disrupt the sediment beneath carrion to a depth of at least 10 cm, which has implications for cave sediment stratigraphy. A laboratory population of the staphylinid cave beetle Quedius mesomelinus was established to examine its life history and behaviour. It was concluded that the species shows a number of adaptations to cavernicolous life, including a K-selected reproductive strategy.

Item Type: Thesis
Creators: Macdonald, J.
Date: July 1992
Divisions: Schools > School of Science and Technology
Depositing User: Jonathan Gallacher
Date Added: 18 Oct 2016 09:36
Last Modified: 18 Oct 2016 09:36
URI: http://irep.ntu.ac.uk/id/eprint/28872

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