Biodiversity and spatial distribution of potentially ciguatera-causing dinoflagellates using DNA metabarcoding

Area of Science:

• Marine biology
• Microbiology
• Food safety

Background:

• Ciguatera poisoning (CP) is a foodborne illness caused by ciguatoxins from Gambierdiscus and Fukuyoa dinoflagellates.
• CP is expanding beyond tropical regions, with increasing reports in the Canary Islands and presence of potentially toxic species in the Balearic Islands.
• Accurate identification of these species is vital due to varying toxin levels and their low-density presence.

Purpose of the Study:

• To assess the utility of DNA metabarcoding targeting the D1-D2 LSU rDNA region for detecting Gambierdiscus and Fukuyoa species.
• To survey the microeukaryotic communities, including potentially harmful dinoflagellates, in the Canary and Balearic Islands.
• To identify problematic Gambierdiscus and Fukuyoa species in these regions.

Main Methods:

• DNA metabarcoding using the D1-D2 LSU rDNA region.
• Analysis of benthic microeukaryotic communities in the Canary and Balearic Islands.
• Identification and quantification of Gambierdiscus and Fukuyoa species and other dinoflagellates.

Main Results:

• DNA metabarcoding successfully detected Gambierdiscus and Fukuyoa species in both archipelagos.
• Predominant species identified were G. australes in the Balearics and G. excentricus and G. silvae in Gran Canaria.
• New records include F. ruetzleri in the Canaries and G. carolinianus in the Balearics, alongside a potential new Gambierdiscus species ('occultus').

Conclusions:

• LSU rDNA-based metabarcoding is a powerful tool for studying benthic microeukaryotic communities, including harmful dinoflagellates.
• The study highlights the presence and distribution of potentially ciguatoxin-producing species in the Canary and Balearic Islands.
• This method aids in early detection and monitoring of species linked to ciguatera poisoning.