Ecosystem resilience on carrion with delayed Diptera colonization

Carrion is an unpredictable and ephemeral resource in the ecosystem. There are wide varieties of organisms, such as vertebrate scavengers, arthropods, and prokaryotes, that recycle nutrients associated with carrion back into the ecosystem. Previous study has shown that there were significant changes in the bacterial metabolic profile during active decay stage of carrion decomposition. However, carcasses without dipteran colonization for a prolonged period (> 5 d) have not been examined for microbial metabolic community profiles as well as the ecosystem resiliency (i.e., the ability to recover after perturbations), especially in bacterial function. Two field trials were conducted in the consecutive summers of 2013 and 2014 in Snook, Texas, USA using nine pig carcasses per year divided into three groups: control (immediately colonized by dipteran species) and two treatments designated as post-7 and post-14, which were delayed for Diptera colonization for 7 days and 14 days, respectively. Swabs were obtained from oral, skin and anal from the pig carcasses while soil samples were collected from beneath, at the side and 5-meter distant away from the carrion for time period of Day 0 (initial day of trial), 7, 14, 21 and 40 for all groups. Bacterial function examined using Biolog EcoPlate^TM, and the resulting spectrometry data were analyzed. Results indicate a significant difference between control, post-7 and post-14 group on pig carcasses, indicating loss of bacterial resilience in metabolism by delaying blow fly colonization. In contrast, soil samples demonstrated no significant change in soil metabolic profiles among treatments, representing a higher resilience capacity in the soil. However, comparison between years showed significant difference in bacterial metabolism profiles and this could be due to significant change in the temperatures during the 40-d study period indicating microbial function associated vertebrate carrion possibly fitting a Gleasonian, rather than Clementsian, model for ecosystem succession.  Furthermore, soil chemistry dynamics (i.e., ammonium, nitrate, phosphate) associated with the carrion decomposition island (CDI) will be discussed in this presentation.