Saint Peter and Saint Paul Archipelago barcoded: Fish diversity in the remoteness and DNA barcodes reference library for metabarcoding monitoring

Anthropogenic pressures have been depleting the global biodiversity. In order to monitor the changes in ecosystems, molecular techniques can be used to characterize species composition. Among molecular markers capable of identifying species, the COI is the most used, and its sequencing is the standard procedure of how taxonomic information can be surveyed. Despite this, new possibilities of biodiversity profiling have become possible through the assessment of highly fragmented DNA molecules in environmental samples. Now, medium- and short-length markers are used in metabarcoding studies. Here, a survey of marine fish from the Saint Peter and Saint Paul Archipelago was barcoded, in which the COI barcode procedure identified 21 species of 11 families of fish. Then, the first extensive COI library of these islands located in isolation was constructed; from these sequences, the most appropriate primer pair for future metabarcoding studies was identified. The new Saint Peter and Saint Paul sequence database has 9,183 sequences from 165 species and 62 families of fish. The overall mean distance among all sequences was 0.4. This distance reveals that the archipelago is a reservoir of biodiversity as this attribute is higher than other islands around the world. Due to this, the protection of the archipelago should be enhanced and well monitored with science-based approaches such as DNA metabarcoding. In this case, the primer pair specifically designed from this library should be considered.