Title

The ecology of carrion decomposition necrophagous invertebrate assembly and microbial community metabolic activity during decomposition of sus scrofa carcasses in a temperate mid-west forest

Date of Award

2011

Degree Name

M.S. in Biology

Department

Department of Biology

Advisor/Chair

Advisor: M. Eric Benbow

Abstract

Decomposition is a fundamental process to ecosystem function and energy flow where nutrients are recycled and reintroduced into food webs. Vertebrate carrion decomposition can provide significant resource pulses for habitats and can range from large whale carcasses to small rodents. Necrophagous invertebrates have been documented to be a predominant driver of vertebrate carrion decomposition. However, microorganisms also participate in the utilization of this common food fall, microorganisms. Little is known about the structure and composition of the microbial communities associated with carrion, or if they follow a pattern of succession as decomposition progresses, although this process is important for nutrient and energy cycling in ecosystems. The objective of this study was to evaluate both the microbial and invertebrate community succession during carrion decomposition. It was hypothesized that microbial and invertebrate communities on decomposing carcasses would vary both over decomposition time and between seasons, as well demonstrates inter-carcass variation among the replicates. To test these hypotheses, Sus scrofa carcasses (N=3-6) were placed in a forested habitat near Xenia, OH during spring (15 March -- 8 June 2009) summer (23 July -- 31 August 2009), autumn (11 November 2009 -- 1 May 2010) and winter (2 February -- 1 May 2010). For the microbial sample collections skin biopsies and swabs of the anus and buccal of each carcass along with cores of soil underneath and 1m away were collected to compare with microbial community metabolic succession during decomposition. Biolog EcoPlates, phenotypic microarray 96 well plates were used to monitor the differential use of 31 different carbon sources to provide a community level physiological profile (CLPPs) as a measure of microbial community metabolic activity. In addition, standardized insect samples involving aerial sweep nets, pitfall traps and hand collections were used to evaluate the arthropod communities through the entire process of carrion decomposition. One and two-way ANOVA with Bonferroni Post-tests, non-metric multidimensional scaling (NMDS), multi-response permutation procedure (MRPP) and indicator species analysis (ISA) were employed to evaluate the microbial community metabolic activity and invertebrate community change over decomposition, between replicates, and between seasons. For the microbial communities, there were significant differences (p<0.001) between seasons for both carrion and soil samples. Carrion samples were significantly different from soil samples (p<0.001), but the control and soil under body were not (p=0.271). For the invertebrates, while most taxa remained constant among seasons, five taxa demonstrated significant differences (One-way ANOVA; p<0.05) in presence across seasons. Necrophagous insect communities had significant differences across the different stages of decomposition (MRPP; p<0.001) for each season in multivariate analyses. According to pairwise comparisons while there were significantly different necrophagous insect communities between summer and fall (p=0.001) and summer and winter (p< 0.001), the communities were similar between fall and winter trials (p=0. 073). Another observation was a undocumented phenomenon concerning en masse larval dispersal of the blow fly Phormia regina. We highly recommend that future studies related to carrion decomposition increase replication of carcasses and make comparisons across seasons and year.

Keywords

Biodegradation Research, Carrion insects Research, Microbiologically influenced corrosion Research, Microbial metabolism Research

Rights Statement

Copyright 2011, author

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