Harmful algae diversity from a coastal upwelling system detected by high-throughput sequencing

Introduction In recent years, environmental DNA (eDNA) amplicon sequencing has been used to unveil plankton diversity in the field. Nevertheless, molecular methods, such as this, are rarely harmful algal bloom (HAB) monitoring programs, which mainly rely on morphological identification by conventional light microscopy. Methods The present study focused a shallow marine environment (Ría de Vigo, Northwest Spain), where sediment and samples were collected from 2016 2018. Results application of eDNA allowed us simultaneously detect 25 potential species (mainly diatoms dinoflagellates) included IOC-UNESCO Taxonomic Reference List Harmful Microalgae. Among these, causative agents amnesic shellfish poisoning ( Pseudo-nitzschia spp.) paralytic Gymnodinium catenatum Alexandrium minutum ), azaspiracid producers Azadinium poporum ) ichthyotoxic haptophytes Chrysochromulina leadbeateri identified. Some toxic microalgae better represented (e.g., pungens , or planktonic fractions smaydae confirming importance including both studies. Despite limitations short amplicons, it was possible discern this six associate each them with seasonal peak produced summer periods. Furthermore, several previously unreported Ría Vigo turgidula could be detected. Discusion These results point out expand our knowledge about HAB programs early warning systems for low abundant rare taxa.