AME 86:185-190 (2021)  -  DOI: https://doi.org/10.3354/ame01965

ABSTRACT: We used 18S rRNA gene metabarcoding to investigate picoeukaryotic diversity and distribution at the surface and deep chlorophyll maximum (DCM) of 4 stations in the eastern equatorial Indian Ocean (EEIO). The results showed that picoeukaryotic communities were dominated by 5 phyla: Dinoflagellata, Radiolaria, Chlorophyta, Ochrophyta and Ciliophora. The picoeukaryotic communities were classified into 3 groups matching their water mass origins and depth: (1) Group I was in the surface waters of the Bay of Bengal, which had low salinity, and was dominated by Radiolaria Group A, Spirotrichea and marine stramenopiles; (2) Group II was in the DCM within the intrusion of Arabian Sea high salinity water, in which Chloropicophyceae and Pelagophyceae were more abundant; and (3) Group III was located in the 0°-5°S surface water, which was enriched by Dinophyceae. In addition, Caecitellaceae paraparvulus was abundant at 4°S, where weak vertical mixing occurred. This study provides the first baseline of picoeukaryotic diversity in the EEIO.

KEY WORDS: Picoeukaryotes · Diversity · 18S rRNA gene metabarcoding · Water masses · Eastern equatorial Indian Ocean