Temporal and Spatial Impact of Human Cadaver Decomposition on Soil Bacterial and Arthropod Community Structure and Function

Abstract

As vertebrate carrion decomposes, there is a release of nutrient-rich fluids into the underlying soil, which can impact associated biological community structure and function. How these changes alter soil biogeochemical cycles is relatively unknown and may prove useful in the identification of carrion decomposition islands that have long lasting, focal ecological effects. This study investigated the spatial (0, 1, and 5 m) and temporal (3–732 days) dynamics of human cadaver decomposition on soil bacterial and arthropod community structure and microbial function. We observed strong evidence of a predictable response to cadaver decomposition that varies over space for soil bacterial and arthropod community structure, carbon (C) mineralization and microbial substrate utilization patterns. In the presence of a cadaver (i.e., 0 m samples), the relative abundance of Bacteroidetes and Firmicutes was greater, while the relative abundance of Acidobacteria, Chloroflexi, Gemmatimonadetes, and Verrucomicrobia was lower when compared to samples at 1 and 5 m. Micro-arthropods were more abundant (15 to 17-fold) in soils collected at 0 m compared to either 1 or 5 m, but overall, micro-arthropod community composition was unrelated to either bacterial community composition or function. Bacterial community structure and microbial function also exhibited temporal relationships, whereas arthropod community structure did not. Cumulative precipitation was more effective in predicting temporal variations in bacterial abundance and microbial activity than accumulated degree days. In the presence of the cadaver (i.e., 0 m samples), the relative abundance of Actinobacteria increased significantly with cumulative precipitation. Furthermore, soil bacterial communities and C mineralization were sensitive to the introduction of human cadavers as they diverged from baseline levels and did not recover completely in approximately 2 years. These data are valuable for understanding ecosystem function surrounding carrion decomposition islands and can be applicable to environmental bio-monitoring and forensic sciences.

Succession of bacterial communities on carrion is independent of vertebrate scavengers

“…Only a few OTUs were present in both high-scavenging sites. We also examined the relative abundance patterns of OTUs classified as genera reported by previous studies to be associated with macroinvertebrates (Singh et al, 2018;Dharne et al, 2008;Gupta et al, 2011;Gupta et al, 2014;Lee et al, 2014;Shukla et al, 2017;Tóth et al, 2008;Weatherbee, Pechal & Eric Benbow, 2017). All macroinvertebrate-associated genera reached peak relative abundances during the later sampling periods except for Providencia and Myroides (Fig.…”

Water Table Drawdown Alters Soil and Microbial Carbon Pool Size and Isotope Composition in Coastal Freshwater Forested Wetlands

“…A change in the microbial community structure could also confer changes in microbial extracellular enzyme production and substrate use (Lerch et al, 2011;Singh et al, 2018), and therefore drive observed patterns of MBC 13 C under different environmental conditions found in coastal forests (Boschker et al, 1999;Wang et al, 2015). Soil organic C is also a complex mixture of organic compound classes, which exhibit a range of 13 C (Bowling et al, 2008), and therefore changes in the microbial community structure and/or enzyme capacity of the soil microbial community could alter microbial C substrate use and δ 13 C of microbial biomass.…”

Microbial succession from a subsequent secondary death event following mass mortality

“…For each biomass there was one fenced and one unfenced replicate located at least 100 m apart to exclude large scavengers and to reduce the likelihood of microbial crossover from other sites, and aid in the isolation of invertebrate communities (Fig. 1) [8]. Fencing was constructed with rolled wire fencing surrounding an area of approximately 2 m 2 , and each plot was further covered with a black plastic mesh.…”