Co-occurrence patterns and temporal changes of dinoflagellate communities in a semi-enclosed bay: Intensive monitoring of predominant key species

Abstract

To understand the dynamics of dinoflagellates on the southern coast of South Korea, the total Phytoplankton transition was analyzed through 18s rDNA Metabarcoding analysis at 3 days of intensive (260-time series monitoring) from November 2018 to June 2020. In a total of 16,224 ASVs (amplicon sequencing variables), 38% of dinoflagellate taxa appeared in total relative abundance. The dinoflagellates community was classified into 21 groups using Bray-Curtis dissimilarity, but their groups showed no significant differences (p>0.05). In common, the appearance of dinoflagellate taxa (with a mean relative abundance >1% in all samples) was selected as the 11 dominant taxa. The predominant taxa were Heterocapsa rotundata (ASV#002, dominance of most investigated times), Euduboscquella sp. (Feb.-Mar.), Dissodinium pseudolunula (Feb.-Mar.), Sinophysis sp. (Feb.-Mar.), Spiniferites ramosus (Mar.), Gymnodinium sp. (May-Jun.), Amoebophyra sp. (Jun.-Jul.), Karlodinium veneficum (Aug.-Sep.), Protodinium simplex (Oct.), Akashiwo sanguinea (Oct.-Nov.), Katodinium glaucum (Nov.). In CCA and Multiple regression analyses, each species in common dinoflagellate taxa had different impacts from competition, predation, parasitism, and environmental factors. In particular, Heterocapsa rotundata and Gymnodinium sp. were significantly strongly affected by predators and competitors (R2=0.999, p<0.001). However, Akashiwo sanguinea was strongly affected by environmental factors (R2=0.349, p<0.001). Thus, when dinoflagellates did not bloom, biological factors also had strong influences, but when red tide did occur, environmental factors had a main influence over other biological influences.