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The effect of cadavers, blood, urine and faeces on soil ecology (CADAVER-2)

English title The effect of cadavers, blood, urine and faeces on soil ecology (CADAVER-2)
Applicant Mitchell Edward
Number 163431
Funding scheme Project funding (Div. I-III)
Research institution Laboratoire de biologie du sol Institut de biologie Université de Neuchâtel
Institution of higher education University of Neuchatel - NE
Main discipline Ecology
Start/End 01.01.2016 - 31.12.2018
Approved amount 294'157.00
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All Disciplines (3)

Discipline
Ecology
Zoology
Environmental Research

Keywords (8)

microbial ecology; bioindication; cadaver decomposition; soil ecology; forensic science; soil invertebrates; ecological succession; soil protozoa

Lay Summary (French)

Lead
La décomposition des cadavres représente une perturbation naturelle des écosystèmes, enrichissant fortement, mais de manière temporaire le milieu en nutriment. Les organismes répondent à cette perturbation, négativement ou positivement et des successions de communautés sont donc observées. Ainsi les cadavres contribuent à augmenter l’hétérogénéité du milieu et donc sa diversité globale. Le premier but de ce projet est d’étudier ces effets.Les successions d’insectes décomposant les corps sont utilisées pour estimer la date de la mort d’une personne durant le premier mois. Les communautés d’organismes du sol réagissent aussi fortement, et sur plusieurs mois. L’étude des dynamiques temporelles des communautés du sol sous les cadavres permettrait donc de développer de nouveaux outils forensiques. Le deuxième but de ce projet est de comparer les effets des cadavres à ceux de l’urine, des fèces ou du sang afin de rechercher des indicateurs spécifiques aux cadavres.
Lay summary

Dans des recherches passées et en cours nous avons étudié les effets de cadavres de cochons sur les organismes du sol. Les résultats montrent des réponses très claires des thécamoebiens (amibes), nématodes et micro-eucaryotes en général (étudiés par des méthodes de séquençage massif Illumina) aux perturbations drastiques des caractéristiques chimiques du sol. Trois années après le début de la décomposition les communautés de micro-eucaryotes sont encore clairement différentes de celles des parcelles non-impactées par les cadavres. Le potentiel de notre approche a été confirmé par l’étude d’un car réel (homicide possible).

Ce projet nous permettra de 1) poursuivre l’étude à long-terme des successions de communautés d’organismes du sol jusqu’au moment où l’impact des cadavres ne sera plus significatif, 2) déterminer si les os seuls peuvent également influencer les communautés du sol, ceci étant justifié par le fait que dans la nature les charognards consomment une grande partie des corps et dispersent les os et 3) adresser des nouvelles questions sur la spécificité des réponses des organismes du sol aux cadavres en comparaison avec d’autres sources de nutriments comme le sang, l’urine ou les fèces.

Dans les différentes parties de ce projet nous combinerons des analyses chimiques du sol, et des analyses morphologiques et moléculaires de la diversité des organismes du sol. Sur la base de séquences courtes d’ADN obtenues par séquençage massif nous avons identifié des bioindicateurs potentiels. Ces indicateurs seront à présent caractérisés plus précisément sur la base de séquences plus longues et par analyse morphologique par hybridisation in-situ par fluorescence (FISH).

Direct link to Lay Summary Last update: 13.10.2015

Responsible applicant and co-applicants

Employees

Publications

Publication
Comparative analysis of bones, mites, soil chemistry, nematodes and soil micro-eukaryotes from a suspected homicide to estimate the post-mortem interval
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.
Soil chemistry changes beneath decomposing cadavers over a one-year period
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.
Soil protists: a fertile frontier in soil biology research
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.
The importance of Saprinus semistriatus (Coleoptera: Histeridae) for estimating the minimum post-mortem interval
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.
Effects of decomposing cadavers on soil nematode communities over a one-year period
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.
Response of forest soil euglyphid testate amoebae (Rhizaria: Cercozoa) to pig cadavers assessed by high-throughput sequencing
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.

Collaboration

Group / person Country
Types of collaboration
University of Neuchâtel, Laboratory of Functional Ecology Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure
Institute of Forensic Medicine, Frankfurt am Main Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
SRUC: Scotland's Rural College Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
University of Reading, School of Biological Sciences Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication

Communication with the public

Communication Title Media Place Year
Media relations: radio, television Einstein: Mumien-Kampf gegen den Zerfall, Wie tote Schweine helfen, kunftige Kriminalfälle aufzuklä SRF German-speaking Switzerland 2016
Media relations: print media, online media Mit Schweinen Kriminalfälle lösen Nordwestschweiz German-speaking Switzerland 2016
Media relations: print media, online media Schweine fur die Forensik, 06.12.2016. St. Galler Tagblatt German-speaking Switzerland 2016
Media relations: print media, online media Tote Schweine sollen helfen, Kriminalfälle zu lösen Sudostschweiz German-speaking Switzerland 2016
Media relations: print media, online media Tote Schweine sollen helfen, Kriminalfälle zu lösen, Berner Oberländer/Thuner Tagblatt, German-speaking Switzerland 2016

Associated projects

Number Title Start Funding scheme
182531 Biodiversity and biogeography of soil protists in continental and oceanic islands 01.01.2019 Project funding (Div. I-III)
141188 The effect of cadavers on soil ecology: biotic and functional responses (CADAVER) 01.08.2012 Project funding (Div. I-III)

Abstract

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.
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