Antifreeze preserves benthic arthropods

Preservation of DNA in bulk environmental samples is conventionally achieved using ethanol, however transportation restrictions, particularly from remote locations, are problematic. We examined the efficacy of an easily accessible, non-toxic propylene glycol-based antifreeze as an alternative to molecular grade ethanol for preserving macroinvertebrate DNA from bulk-benthos DNA samples. We tested the differences in both cytochrome oxidase I (COI) exact sequence variants (ESVs) and COI taxonomic orders detected in both ethanol and antifreeze samples using two processing methods (no evaporation of preservative versus full evaporation). Our results suggest that antifreeze is a suitable alternative to ethanol for preservation of DNA in freshly collected samples due to the comparable ESV richness detected in antifreeze-preserved samples. We have demonstrated that by using antifreeze, it is possible to achieve sufficient taxonomic coverage and assess macroinvertebrate assemblages within bulk-benthos DNA samples. The application of this non-regulated preservative is particularly important for remote sampling (i.e. only air accessible) and sampling for community-based biomonitoring projects within Indigenous territories where alcohol is prohibited or not available.