Nematode Community Succession in Vertebrate Carcass Decomposition Soil Hot Spots.

Vertebrate carcass decomposition produces localized soil enrichment zones resulting in increased fertility and nutrient cycling. Bacterial successional changes have been observed in these zones as cadaver microbiome constituents enter the soil during active decomposition and mass-loss. While both microbial and entomological successions have been documented during this time period, changes in soil microfauna have not been well-studied, despite their assumed importance in the local food web. Nematodes in particular, are regarded as sentinel organisms that can describe the nature of a soil and its health, and their community-level responses in a decomposition zone may prove to be useful as a temporal benchmark for determining the post-mortem interval (PMI). The objectives of this study were to evaluate the development and changes in soil nematode communities under decomposing vertebrate carcasses (North American beaver, Castor canadensis) in an Appalachian mixed mesophytic hardwood forest. Internal carcass temperatures, ambient temperatures, and soil electrical conductivity were continually monitored, and insects and surface soils were collected underneath the beavers during each decomposition phase. Soil nematodes were characterized to genus level. Prior to placement, soil nematode communities were dominated by Helicotylenchus erythrinae (phytoparasite) and an array of Tylenchidae (fungivores). The most abundant bacterivores were four species of Plectidae; Rhabditidae and Diplogasteridae were minor components. The enrichment of soil with carcass-derived nutrients during decomposition resulted in a significant reduction in nematode community diversity. The most notable changes were increased populations of Rhabditidae and Diplogasteridae (>90% of community) and an increase in predaceous Dorylaimida and Mononchida. Documenting these patterns in nematode succession will contribute to our understanding of soil ecology responses to nutrient hot spot enrichments associated with carcass decomposition.