Molecular barcoding confirms the presence of exotic Asian seaweeds ( and ) in the Cantabrian Sea, Bay of Biscay.

BACKGROUND

The introduction of exotic species can have serious consequences for marine ecosystems. On the shores of the Cantabrian Sea (North of Spain) there are no routine examinations of seaweeds that combine molecular and morphological methods for early detection of exotic species making it difficult to assess in the early stages their establishment and expansion processes as a result of anthropogenic activities (e.g., shipping and/or aquaculture).

METHODS

In this work we used both morphological identification and molecular barcoding (COI-5P and L genes) of red algae collected in Asturias, Bay of Biscay (Gijón and Candás harbours) and from the University of Oviedo's herbarium samples.

RESULTS

The results confirmed the presence of exotic Asian seaweeds and Yamada on Cantabrian Sea shores. Several individuals of these species were fertile and developing cystocarps when collected, underlining the risk of possible expansion or continued establishment. This study constitutes the first report of the Asian in this area of the Bay of Biscay.

CONCLUSIONS

Here the presence of the exotic species of the Halymeniales is confirmed. We hypothesize that this species may have been established some time ago as a cryptic introduction with in Galician shores. The detection of these species on the shores of the Cantabrian Sea is relevant since introductions of species could have been overlooked on other European coasts, probably mixed with and . Our results confirm one new alien seaweed species that has been detected using molecular methods (COI-5P region and L genes barcoding) on North Atlantic shores: the Asian native . This demonstrates that routine screening for early detection of exotic algae in the Cantabrian Sea can be used for risk assessment. Genetic barcoding should be done using both L gene and COI-5P regions since, although COI-databases are still poorer in sequences and this inhibits successful outcomes in -related species identifications, it is nonetheless a useful marker for species-level identifications in seaweeds.