Spatial and temporal distribution patterns of marine stramenopiles in Daya Bay, South China

Abstract

Molecular surveys have revealed a surprisingly large novel diversity of heterotrophic nanoflagellates affiliated with MArine STramenopiles (MAST) in marine systems. It has been proved that MAST cells are globally distributed and efficient bacterial grazers, therefore playing indispensable roles on ecosystem functioning. Nevertheless, MAST organisms remain uncultured and data on distribution and trophic modes are limited. Here we investigated their composition and seasonal variability using Illumina high- throughput sequencing targeting 18S rDNA in Daya Bay. MAST accounted for 0.5% in winter and up to 2.1% in spring of total 18S rDNA sequences in the pico- nano fraction. Within MAST, sequences affiliated with eight groups (-1, -2, -3, -4, -6, -7, -8 and -12) were widely distributed in both seasons. On average, the most abundant groups were MAST-3 (45.8% of the total MAST sequences), MAST-1 (30.4%), MAST-2 (7.5%) and MAST-12 (6.3%). This study demonstrated some key physicochemical (water temperature and salinity) factors significantly explained MAST composition variations. As being potential bacterial predators, prey abundance as well as their quality were also responsible for shaping MAST spatial distribution and community structure. Given the importance of MAST function, this study contributes to broaden our understanding of the diversity and distribution of MAST community and helps refine hypotheses on their ecological characteristics.