Long-term archival of environmental samples empowers biodiversity monitoring and ecological research

Human-induced biodiversity loss and changes in community composition are major challenges of the present time, urgently calling for comprehensive biomonitoring approaches to understand system dynamics and to inform policy-making. In this regard, molecular methods are increasingly applied. They provide tools for fast and high-resolution biodiversity assessments and can also focus on population dynamics or functional diversity. If samples are stored under appropriate conditions, this will enable the analysis of DNA, but also RNA and proteins from tissue or from non-biological substrates such as soil, water, or sediments, so-called environmental DNA (eDNA) or eRNA. Until now, most biodiversity studies using molecular methods rely on recent sampling events, although the benefit of analyzing long-time series is obvious. In this context Environmental Specimen Banks (ESBs) can play a crucial role, supplying diverse and well-documented samples collected in periodically repeated sampling events, and following standardized protocols. Mainly assembled for integrative monitoring of chemical compounds, ESB collections are largely accessible to third parties and can in principle be used for molecular analysis. While ESBs hold great potential for the standardized long-time storage of environmental samples, the cooperation with Biodiversity Biobanks as scientific collections guarantees the long-time storage of nucleotide (DNA, RNA) extracts together with links to analytical results and metadata. The present contribution aims to raise the awareness of the biodiversity research community regarding the high-quality samples accessible through ESBs, encourages ESBs to collect and store samples in DNA-friendly ways, and points out the high potential of combining DNA-based approaches with monitoring chemicals and other environmental stressors.