microbial ecology; bioindication; cadaver decomposition; soil ecology; forensic science; soil invertebrates; ecological succession; soil protozoa
Szelecz Ildikó, Lösch Sandra, Seppey Christophe V. W., Lara Enrique, Singer David, Sorge Franziska, Tschui Joelle, Perotti M. Alejandra, Mitchell Edward A. D. (2018), Comparative analysis of bones, mites, soil chemistry, nematodes and soil micro-eukaryotes from a suspected homicide to estimate the post-mortem interval, in Scientific Reports
, 8(1), 25-25.
Szelecz Ildikó, Koenig Isabelle, Seppey Christophe V.W., Le Bayon Renée-Claire, Mitchell Edward A.D. (2018), Soil chemistry changes beneath decomposing cadavers over a one-year period, in Forensic Science International
, 286, 155-165.
Geisen Stefan, Mitchell Edward A D, Adl Sina, Bonkowski Michael, Dunthorn Micah, Ekelund Flemming, Fernández Leonardo D, Jousset Alexandre, Krashevska Valentyna, Singer David, Spiegel Frederick W, Walochnik Julia, Lara Enrique (2018), Soil protists: a fertile frontier in soil biology research, in FEMS Microbiology Reviews
, 42(3), 293-323.
Szelecz I., Feddern N., Seppey C.V.W., Amendt J., Mitchell E.A.D. (2018), The importance of Saprinus semistriatus (Coleoptera: Histeridae) for estimating the minimum post-mortem interval, in Legal Medicine
, 30, 21-27.
Szelecz Ildikó, Sorge Franziska, Seppey Christophe V.W., Mulot Matthieu, Steel Hanne, Neilson Roy, Griffiths Bryan S., Amendt Jens, Mitchell Edward A.D. (2016), Effects of decomposing cadavers on soil nematode communities over a one-year period, in Soil Biology and Biochemistry
, 103, 405-416.
Seppey Christophe V. W., Fournier Bertrand, Szelecz Ildikò, Singer David, Mitchell Edward A. D., Lara Enrique (2016), Response of forest soil euglyphid testate amoebae (Rhizaria: Cercozoa) to pig cadavers assessed by high-throughput sequencing, in International Journal of Legal Medicine
, 130(2), 551-562.
Decomposing cadavers impact the soil ecosystem by massive inputs of nutrients producing a “cadaver decomposition island (CDI)”. This pulse of resources affects the soil biota (diversity and community structure) and functions drastically; yet these effects are not well understood. Furthermore, even less is known about how these effects compare to those induced by other nutrient pulses from faeces, urine, and - especially relevant in a forensic context - blood. Resource pulses contribute to enhancing regional biodiversity through the contrasted responses of different taxa and the spatial and temporal heterogeneities they generate. Once decomposition is completed and nutrients are leached or diluted in the landscape the soil ecosystem should gradually return to a “normal” condition. These patterns and processes are relevant to general soil biology and to application in forensic science where there is growing interest in this topic especially with the advent of new molecular tools for diversity screening such as next generation sequencing (NGS).A key aspect of forensic research is to develop tools to determine how long ago the death occurred (the post-mortem interval - PMI) and if a cadaver has decomposed in a certain place (especially relevant if corpse remains were removed). Forensic pathology tools are not precise beyond 3-4 weeks post-mortem. By carefully documenting changes in the soil biota over a longer period (months to years) both in the disturbance and the recovery phases it should be possible to develop novel tools for PMI estimates and to detect graves.In previous and on-going experiments we have studied the effects of pig cadavers on the soil biota in both fundamental (disturbance and nutrient pulses impact on soil biota) and applied (potential of soil biota and functions as indicators for forensic applications) perspectives. Results show strong responses of soil testate amoebae, nematodes and general micro-Eukaryotic communities (assessed by high throughput Illumina sequencing) in parallel to drastic changes in soil chemistry and to succession of insect communities on the cadavers. After three years soil micro-Eukaryotic communities still showed a clear difference between cadavers and control plots. The study of a real case further demonstrated the validity of our approach.In this project we plan to 1) continue to document the longer-term succession of soil communities until the cadaver impact is no longer significant, 2) assess if bones alone can also influence soil communities (given that in real cases bodies will be partly eaten by scavengers, the bones dispersed and hence the impact of cadavers at different decomposition stages may impact the soil in different places) and 3) address a key unanswered question in forensic science by conducting a new manipulative experiment aiming at assessing if the indicators we have documented are specific to decomposing cadaver or if similar patterns could be observed in response to other nutrient pulses such as urine, faeces and blood.The project is divided into two main tasks each subdivided into 5 specific tasks.1) Further work related to on-going long-term experiments: 1a) general analysis of all Eukaryotes by Illumina sequencing; 1b) detailed analyses of individual indicator taxa by phylogenetic analysis based on full SSU sequences; 1c) morphological characterisation by Fluorescence In Situ Hybridisation (FISH) of selected organisms studied in 1b; 1d) spatial analysis of long-term pigs; 1e) moving bones experiment.2) Additional 1 year mesocosm experiment to assess the effects of urine, faeces, blood and cadavers on soil communities: 2a) Soil chemical analyses; 2b) soil nematodes; 2c) NGS analysis of all Eukaryotes; 2d) Detailed analyses of individual OTUs identified as indicator taxa by phylogenetic analysis based on full SSU sequences; 2e) Morphological characterisation by FISH of selected organisms studied in 2d.