Presentation Information
[P04-539]eDNA-Based Detection of Protists in Hypoxic Coastal Waters: Implications for Monitoring Marine Ecosystems
○Jin Hee Ok1 (1. Hanyang University ERICA (Korea))
Keywords:
eDNA,metabarcoding,Coastal hypoxia,Dinoflagellate,Marine ecosystem monitoring
[Purpose] Coastal hypoxia is increasing, but the protistan taxa that survive under low-oxygen conditions remain poorly understood. Because many protists are too small to be readily identified to species level by microscopy in seawater samples, eDNA-based metabarcoding is needed to characterize these communities. This study aimed to identify protistan communities in hypoxic coastal waters and determine which dinoflagellate taxa persist under oxygen depletion, with implications for marine ecosystem monitoring.
[Method] Protistan communities in Jinhae Bay and Masan Bay, Korea, were analyzed using eDNA metabarcoding targeting the V4 region of the 18S rRNA gene. Surface and bottom water samples were collected during hypoxic and non-hypoxic periods, and amplicon sequence variants (ASVs) were compared among conditions.
[Results] During hypoxia, Dinoflagellata showed the highest ASV richness among protistan groups, and bottom waters contained more protistan ASVs than surface waters. A total of 73 dinoflagellate species were identified, 36 of which occurred in hypoxic waters. Notably, 26 of these had not previously been reported from hypoxic marine waters. Heterotrophic dinoflagellates were relatively more abundant in hypoxic bottom waters.
[Consideration] These findings suggest that trophic flexibility, particularly heterotrophy, may promote dinoflagellate survival under oxygen-depleted conditions and reveal diverse, previously underrecognized protistan assemblages in hypoxic coastal waters.
[Conclusion] eDNA metabarcoding is an effective molecular tool for detecting protists that persist in coastal hypoxia and for monitoring and assessing marine ecosystem responses to deoxygenation.
[Method] Protistan communities in Jinhae Bay and Masan Bay, Korea, were analyzed using eDNA metabarcoding targeting the V4 region of the 18S rRNA gene. Surface and bottom water samples were collected during hypoxic and non-hypoxic periods, and amplicon sequence variants (ASVs) were compared among conditions.
[Results] During hypoxia, Dinoflagellata showed the highest ASV richness among protistan groups, and bottom waters contained more protistan ASVs than surface waters. A total of 73 dinoflagellate species were identified, 36 of which occurred in hypoxic waters. Notably, 26 of these had not previously been reported from hypoxic marine waters. Heterotrophic dinoflagellates were relatively more abundant in hypoxic bottom waters.
[Consideration] These findings suggest that trophic flexibility, particularly heterotrophy, may promote dinoflagellate survival under oxygen-depleted conditions and reveal diverse, previously underrecognized protistan assemblages in hypoxic coastal waters.
[Conclusion] eDNA metabarcoding is an effective molecular tool for detecting protists that persist in coastal hypoxia and for monitoring and assessing marine ecosystem responses to deoxygenation.
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