Examining patterns of marine finfish biodiversity using environmental DNA (eDNA) metabarcoding in Arrábida Marine Park, Portugal

Mary Joyce Velos

Increasing risk to extinction due to habitat loss necessitates biodiversity monitoring to predict ecosystem responses, especially for habitats that harbor unique species assemblage. In this study, eDNA metabarcoding was used to demonstrate patterns of marine finfish biodiversity in Arrábida Marine Park, Portugal and examine differences in diversity and assemblage between habitat types. Results documented sentinel, threatened and invasive species despite only accounting 12% (27 out of 232 finfishes) of the total marine finfish species in the marine park due to potential insufficient sampling. Higher diversity was found in the vegetated habitats compared to non-vegetated counterparts particularly in seagrass-related sites possibly due to differences in habitat complexity. At the regional scale, significant differences in fish communities were observed possibly due to spatiotemporal fluctuations in environmental processes that affect eDNA decay rates. However, differences in fish communities were not established when removing the temporal replicates, suggesting potential connectivity among sites due to eDNA transport. With improved confidence in taxonomy assignment by populating the 12S reference database and using efficient bioinformatics pipelines as some species detected in this study were not assigned to congeners often documented in the marine park, implications derived from eDNA metabarcoding could non-invasively and cost-effectively complement conventional biodiversity techniques.