Distribution of dinoflagellate cysts in surface sediments of Tongyeong coastal waters, South Korea: Application of a next generation sequencing method

Abstract

To characterise the distribution of dinoflagellate cysts, we used next generation sequencing (NGS) after sampling of surface sediments of the Tongyeong coastal lines, South Korea. Sampling was divided into two seasons: a no red tide (52 sites, in December 2013) and a red tide (44 sites, in September 2014). The surface sediment samples were stored at 4 °C in a dark refrigerator for at least 6 months to allow decomposition of organic matter involving living phytoplankton. The NGS analysis revealed 5,270&#8211 13,979 read counts and 175&#8211 273 operational taxonomic units (OTUs) with 97% sequence similarity obtained after quality filtering of analysed sequences. Based on the NGS results, the Stramenopiles-Alveolata-Rhizaria (SAR) was the most abundant group (90.10% and 80.16% of the total analysed read counts of 2013 and 2014, respectively). The Alveolata represented the most dominant subgroup In Alveolata, the Dinophyta was the most abundant group (90.39% and 77.25% for 2013 and 2014, respectively). Identified species in the Dinophyta totalled 32 taxa consisting of 17 genera, 29 species, and 3 unidentified organisms. The presented common groups (classified at genus level), were Pentapharsodinium-Scrippsiella, Alexandrium, Gonyaulax, Gymnodinium, and Woloszynskia. The present result represents the first estimates of the diversity and species composition of dinoflagellate cysts that occur in the Tongyeong coastal sedies, in December 2013) and a red tide (44 sites, in September 2014). The surface sediment samples were stored at 4 °C in a dark refrigerator for at least 6 months to allow decomposition of organic matter involving living phytoplankton. The NGS analysis revealed 5,270&#8211 13,979 read counts and 175&#8211 273 operational taxonomic units (OTUs) with 97% sequence similarity obtained after quality filtering of analysed sequences. Based on the NGS results, the Stramenopiles-Alveolata-Rhizaria (SAR) was the most abundant group (90.10% and 80.16% of the total analysed read counts of 2013 and 2014, respectively). The Alveolata represented the most dominant subgroup In Alveolata, the Dinophyta was the most abundant group (90.39% and 77.25% for 2013 and 2014, respectively). Identified species in the Dinophyta totalled 32 taxa consisting of 17 genera, 29 species, and 3 unidentified organisms. The presented common groups (classified at genus level), were Pentapharsodinium-Scrippsiella, Alexandrium, Gonyaulax, Gymnodinium, and Woloszynskia. The present result represents the first estimates of the diversity and species composition of dinoflagellate cysts that occur in the Tongyeong coastal sedi