| Summary: | Arctic biodiversity has long been underestimated and is now facing rapid transformations due to ongoing climate change and other impacts including shipping activities. These changes are placing marine coastal invertebrate communities at greater risk, especially in sensitive areas such as commercial ports. Preserving biodiversity is a significant challenge, going far beyond the protection of charismatic species and involving suitable knowledge of the organization of species in space. Therefore, knowledge of alpha, beta and gamma biodiversity indices are of great importance in achieving this objective together with new cost-effective approaches to monitor changes in biodiversity. This study compares metabarcoding of COI mitochondrial genes and 18S rRNA genes from environmental DNA (eDNA) water samples with standard species collection methods to document patterns of invertebrate communities at various spatial scales. Water samples (250 mL) were collected at three different depths within three Canadian Arctic ports; Churchill, MB, Iqaluit, NU and Deception Bay, QC. From these samples, 202 genera distributed across more than 15 phyla were detected using eDNA metabarcoding, of which only 9% to 15% were also identified through species collection at the same sites. Significant differences in taxonomic richness and community composition were observed between eDNA and species collections, both on local and regional scales. This study shows that eDNA dispersion in the Arctic Ocean reduces beta diversity in comparison to species collection while emphasizing the importance of pelagic life stages for eDNA detection. This study highlights the potential of eDNA metabarcoding to assess large-scale arctic marine invertebrate diversity while emphasizing that eDNA and species collection should be considered as complementary tools for providing a more holistic picture of the marine invertebrate communities living in coastal areas. D’abord méconnue puis longuement sous-estimée, la biodiversité de l’Arctique fait maintenant face à ...
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