Development of a field-based earthworm mark-release-recapture technique for biomonitoring

Abstract

Biomonitoring in soil systems presents difficulties in retrieval and differentiation of test organisms from local populations. The aim of this study was to develop a simple method of in situ containment and efficient retrieval of earthworms. Visible Implant Elastomer (VIE) tags were used to identify earthworms Lumbricus rubellus and Aporrectodea caliginosa introduced to unpolluted pasture or a polluted site. Containment PVC tubes of different height (inserted differently into the soil and covered or not covered by a mesh) were used. Highest recovery rates for both species came from use of 0.3 m tubes (100% for A. caliginosa and 71% for L. rubellus). This study confirmed the feasibility of using VIE tags to identify and aid recovery of introduced earthworms from field experiments. Results suggested that recovery rates were influenced by behavioural differences in ecological groupings and site-specific factors. There is scope for further improvement in the tagging procedure, mortality assessment and investigation of containment for earthworms.