Micromonas, a small pigmented flagellate, predominates the nanoflagellate and photosynthetic picoeukaryote communities in the northern South China Sea

• Published in: Environmental microbiology reports 2024-04, Vol.16 (2), p.e13244-n/a
• Main Authors: Guo, Xin, Pang, Mengwen, Zheng, Xinyi, Huang, Lingfeng
• Format: Article
• Language: English
• Subjects: China; Chlorophyta; In Situ Hybridization, Fluorescence; Oceans and Seas; Pacific Ocean; Photosynthesis; Seawater
• ISSN: 1758-2229; 1758-2229
• DOI: 10.1111/1758-2229.13244

A small pigmented flagellate, Micromonas, is prevalently distributed in coastal and pelagic waters. However, there have been few studies conducted to quantify their abundance in the marginal seas of the Northwest Pacific Ocean. In this study, we used fluorescent in situ hybridization with tyramide signal amplification (TSA‐FISH) to reveal the spatial distribution of Micromonas in the northern South China Sea (SCS). On average, the abundance of Micromonas was 317 cells mL−1, with the average proportions in the nanoflagellates (NF) and photosynthetic picoeukaryotes (PPE) communities being 10.94% and 15.39%, respectively. This indicates a wide distribution and dominance of this genus in the studied area. The relationships between Micromonas abundance and various environmental factors suggested that biotic correlations play more important roles than physicochemical filtering on Micromonas assemblage. This may indicate a broad environmental adaptation spectrum of this genus through its flexibility in terms of resource acquisition strategies. In summary, this study provides insight into the spatial distribution pattern of Micromonas and highlights its crucial contribution to the composition of NFs and PPE communities, which rely on biological interaction to respond to the changing environmental conditions in the northern SCS. Employing fluorescent in situ hybridization with tyramide signal amplification (TSA‐FISH), we specifically detected and quantified the genus Micromonas. This genus exhibited a vertical distribution across both nearshore and offshore habitats in the northern South China Sea, forming a significant proportion of the microbial community. The prevalence and dominance of Micromonas may be attributed to its flexible mixotrophic strategy, where both inorganic nutrients and food sources (such as bacteria) play crucial roles in its assembly.