Temporal and spatial impact of human cadaver decomposition on soil bacterial and arthropod community structure and function

Authors: SINGH, BANESHWAR - Virginia Commonwealth University; MINICK, KEVAN - North Carolina State University; STRICKLAND, MICHAEL - University Of Idaho; WICKINGS, KYLE - Cornell University; Crippen, Tawni - Tc; TARONE, AARON - Texas A&M University; BENBOW, ERIC - Michigan State University; SUFRIN, NESS - Bode Cellmark Forensics; TOMBERLIN, JEFFERY - Texas A&M University; PECHAL, JENNIFER - Michigan State University

Submitted to: Frontiers in Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/14/2017
Publication Date: 1/4/2018
Publication URL: https://handle.nal.usda.gov/10113/6472455
Citation: Singh, B., Minick, K.J., Strickland, M.S., Wickings, K., Crippen, T.L., Tarone, A.M., Benbow, E., Sufrin, N., Tomberlin, J.K., Pechal, J.L. 2018. Temporal and spatial impact of human cadaver decomposition on soil bacterial and arthropod community structure and function. Frontiers in Microbiology. 8(2616):1-12. https://doi.org/10.3389/fmicb.2017.02616.
DOI: https://doi.org/10.3389/fmicb.2017.02616

Interpretive Summary: As bodies decompose, they release nutrient-rich fluids to the underlying soil, which affects the number and type of bacteria and arthropods (mites) present in the soil beneath. The changes to the soil and its bacterial and arthropod communities caused by these fluids are not known, so this study looks at the changes under a decomposing body at zero and five meters away over a two year period. Changes to the makeup and abundance of bacteria and mites and to the function of bacteria (their use of carbon) were measured along with rainfall and temperature. For bacteria, there was a strong relationship between the type of bacteria and their use of carbon for both the distances (0 or 5 m) and the time lapse (over 2 y). For arthropods, there was a strong relationship between the species makeup and the distances, but not the time of the decay. The initial size of the body (mass) and the rainfall explained bacterial quantity and activity more effectively than did temperature. The changes in these two communities after the introduction of the body did not return to normal (prior to the introduction of the body) over the two years of sampling. These data are valuable for understanding ecosystem function surrounding carrion decomposition and can be applicable to environmental bio-monitoring, livestock die-offs, and forensic sciences.

Technical Abstract: As cadavers decompose, they release nutrient-rich fluids into the underlying soil, which can impact associated microbial and arthropod 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 to 5 m from human cadavers) and temporal (3 to 732 days) soil bacterial community structure and function, and soil arthropod community structure associated with human cadaver decomposition. We observed strong evidence of a predictable response to cadaver decomposition that varies over space in soil bacterial and arthropod community structure, and carbon (C) mineralization and microbial substrate utilization patterns. Bacterial community composition and function also exhibited temporal relationships, whereas arthropod community composition did not. The starting cadaver mass and cumulative precipitation explained bacterial abundance and microbial activity more effectively than accumulated degree days. Furthermore, microbial communities were sensitive to the introduction of vertebrate carrion as they diverged from baseline levels and did not recover for approximately two years. These data are valuable for understanding ecosystem function surrounding carrion decomposition islands and can be applicable to environmental bio-monitoring and forensic sciences.