Metabarcoding analysis of the composition and spatial–temporal dynamics of Pseudo-nitzschia species in Jiaozhou Bay, China

Pseudo-nitzschia is a species-rich genus with many species able to induce harmful algae blooms (HABs) associated with the toxin, domoic acid (DA), production. Despite their high diversity revealed by taxonomical studies, the composition and spatial–temporal dynamics of Pseudo-nitzschia species in marine ecological systems are often inadequately resolved due to the insufficient resolution associated with morphology-based approaches applied in ecological studies. In this study, metabarcoding analysis was applied to identify Pseudo-nitzschia species and track their spatial–temporal dynamics in Jiaozhou Bay (JZB), a model marine ecosystem located in Qingdao, China. This metabarcoding analysis potentially uncovered 18 Pseudo-nitzschia species, including three Pseudo-nitzschia species identified in JZB in previous microscopy-based studies, four Pseudo-nitzschia species (P. micropora, P. multistriata, P. galaxiae, and P. fraudulenta) that have not been identified in JZB, and 11 potential Pseudo-nitzschia species whose molecular marker sequences are identical, demonstrating the strength of metabarcoding analysis in ecological research. Furthermore, this metabarcoding analysis also revealed differential spatial–temporal dynamics of many Pseudo-nitzschia species. While P. galaxiae was found to show a strong preference for summer months, P. pungens showed relatively high abundance in later summer and early autumn, P. delicatissima and P. multistriata showed higher abundance in autumn and winter, and P. micropora was more common in July. To ascertain driving forces for such differential seasonal preferences, we evaluated the impact of environmental factors on the spatial–temporal preferences of the Pseudo-nitzschia species, which revealed that temperature and other factors together contributed to the differential dynamic changes. This study demonstrated that metabarcoding analysis is an effective approach for tracking the composition and spatial–temporal dynamics of Pseudo-nitzschia species in marine ecological systems.