LB 6-48 - The state of Canada’s freshwater biodiversity: current gaps in molecular genetic resources and future perspectives

Background/Question/Methods:

Canada holds more freshwater bodies than any other nation in the world, but little is known about the general state of freshwater biodiversity due largely to a lack of data. Desforges and colleagues (CJFAS, 2021) conducted a country-wide freshwater biodiversity conservation status assessment and found that a substantial proportion (38%) of freshwater-dependent taxa (i.e., taxa which rely on freshwater habitats during a part of their life cycle) cannot be assessed due to data deficiencies. Biodiversity surveys could be substantially improved through the analysis of environmental DNA (eDNA) if appropriate DNA sequence reference databases exist. Here, we aimed to assess the molecular genetic resources available for Canada’s freshwater species and identify data deficiencies where future research should be directed. We assessed the data coverage for the taxa listed by Desforges et al. in major public sequence repositories (BOLD Systems and NCBI) and compiled sequence data on whole genomes and genetic markers widely used for metabarcoding (COI, 18S, and 12S rRNA genes). We then mapped the distributions of archived genetic data across Canada to (1) highlight geographic regions of data deficiencies and (2) formulate recommendations on how expanded molecular genetic data could be leveraged to inform future biodiversity assessments in underrepresented regions.

Results/Conclusions:

Preliminary results show that 97% of species currently not at risk have at least one genetic record in BOLD Systems, whereas 88% of threatened species and 83% of endangered species were represented in the database. In contrast, only ~3% of all freshwater taxa were catalogued in the NCBI Genome database as having sequenced nuclear genomes, though a greater abundance of taxa are expected to be inventoried under sequenced mitochondrial or chloroplast genomes. Invertebrates had the lowest DNA sequence coverage, with 23% of species absent from the BOLD Systems. Furthermore, the species for which some genetic/genomic records exist are generally located in southern latitudes, leaving “cold spots” of sequence coverage in the more remote regions and towards northern latitudes. Our work contributes to identifying gaps in molecular genetic databases and providing recommendations on priority groups for DNA sequencing to bring the most urgent improvements to conservation status assessments. Our framework could then be applied to other region so that an international priority effort be organised.