Examining tagging option and survival estimates for two riffle beetles in a conservation hatchery

Abstract

Small-bodied invertebrates remain underrepresented in ecological research, with major gaps in survival and life history which hinder effective conservation. The Comal Springs Riffle Beetle, (Heterelmis comalensis) an endangered, crenic beetle endemic to central Texas, exemplifies these challenges. The beetles’ small size complicates recapture and marking, limiting opportunities to estimate survival. This study had two objectives: (1) to synthesize current tagging methodologies for small-bodied organisms through a systematic literature review, and (2) to evaluate the use of said miniaturized tags for riffle beetles under controlled conditions. Based on this synthesis, p-Chips were selected for experimental testing on H. Comalensis and a surrogate species, H. glabra. Tagged beetles were monitored using an automated detection system across four trials lasting 50-150 days. Two trials yielded sufficient detection data to construct matrices for survival estimation while accounting for incomplete detection. Survival was then compared between tagged and untagged groups to assess potential tagging effects. Results suggest a potential effect of p-Chip tagging on H. Glabra, with tagged individuals showing reduced survival relative to controls across one of two experimental trials. No suitable tags currently exist for H. Comalensis, and feasible tagging options will continue to be necessary for future conservation, monitoring and management.