eDNAqua-Plan Deliverable 9: Recommendations for a federated system of taxonomically curated reference libraries

Species identification from environmental DNA (eDNA) sequencing critically depends on the availability and quality of reference sequences to which to compare the obtained environmental sequences. For eDNA-based taxonomic identification to be routinely implemented in aquatic monitoring programs, these taxonomic assignments should be undertaken with quality-controlled and taxonomically curated reference libraries to minimise false or incomplete assignments. These reference libraries should additionally be easy to find and reuse. The current eDNAqua-Plan deliverable report D3.1 outlines the vision of a federated system of taxonomically curated reference libraries, and a set of guiding principles towards achieving this vision. The guidelines contain recommendations of essential metadata that reference libraries should provide, which cover the biological origin, sequence information and taxonomy and taxonomic validation of reference sequences as well as overall library metadata. Subsequently, the report outlines recommended curation procedures focused on sequence quality, taxonomic curation and a ranking of the reference quality. Finally, a proposal of interoperable metadata fields using existing standards and avenues for a decentralised data architecture paves the way towards an interoperable, federated network. These three pillars of essential metadata, curation procedures and interoperability are established to support the eDNAqua-Plan vision of a federated network of curated reference libraries to support reproducible and reliable molecular aquatic biodiversity monitoring in Europe and beyond.