Dynamic measurements of earthworm respiration

Earthworms are critical soil organisms, facilitating biogeochemical cycles in soil ecosystems through the formation of soil aggregates by drilling soil and accelerating microbial activity. However, the dynamic measurements of earthworm respiration have not been updated for several decades, although understanding earthworm respiration is a fundamental step in understanding the role of earthworms in soil biogeochemistry. In the present study, we applied our dynamic measurement system of soil gas exchange to earthworm respiration. Eisenia japonica and Metaphire hilgendorfi, which are typical earthworms in Japan, were used in this study. We continuously measured earthworm respiration in one or two earthworms for the first time. After confirming the possibility of continuous measurement of earthworm respiration in our system, we tested the system’s performance by investigating how earthworm respiration changes in/detached from soil conditions and temperature. Responses to temperature were different between the two species, possibly because of their physiological differences. Earthworm respiration was not different among temporal treatments of in/detached from soil (only 5%-10%). Continuous time-series data of earthworm respiration obtained by the system could be subjected to mathematical time-series analyses. Wavelet analysis showed that various scales of respiration enhancements until 16 min can be observed. Taken together, the application of our system to earthworm studies will considerably enhance our understanding of earthworm sciences in future.