Does carcass decomposition affect soil-dwelling enchytraeids?

Carcass decomposition causes substantial changes in the humidity and chemistry of adjacent soil. Its potential effect on Enchytraeidae (Annelida: Clitellata) has, hitherto, not been studied. This pilot study on the effect of a large vertebrate carcass on enchytraeids was conducted in temperate grassland with sandy soil close to Cottbus (Germany). Soil cores for enchytraeid extraction were taken in June 2013 along four transects of 2.5 m length from the original centre of the carcass. By that time the carcass, exposed in September 2012, had almost entirely decomposed. Soil had been sampled along the transects in February and May 2013 for measurement of chemical characteristics. Enchytraeids were extracted by the wet funnel method (without heating) and identified alive to species. In total, 715 individuals and 8 species were recorded (including Fridericia brunensis, a species known from very few sites). Abundance means had a high variance, and apparent differences were not statistically significant. However, total abundance showed a distinct trend of increase with increasing distance from the carcass site, mostly due to high abundance and dominance of Enchytronia parva. Positive correlation with distance from the carcass was significant for enchytraeids as a group, E. parva and Fridericia spp. Enchytraeids in total and all species or genera tested except Enchytraeus spp. (predominantly E. buchholzi s.l.) had a negative correlation with conductivity. The latter, although not abundant, showed a clear peak at 0.5 m and had a positive correlation with soil pH. Further significant correlations were found between species or genera and pH, phosphate and humus content. In difference to some springtails, enchytraeids at the study site seemed to avoid the vicinity of carcasses, possibly due to high conductivity, ammonium and phosphate ion concentrations and pH of the affected soil. E. buchholzi, an opportunistic, stress-tolerant r-strategist, might be an exception.