Diversity and Spatial Distribution of Chromophytic Phytoplankton in the Bay of Bengal Revealed by RuBisCO Genes (rbcL)

Abstract

Phytoplankton are the basis of primary production and play important roles in regulating energy export in marine ecosystems. Compared to other regions, chromophytic phytoplankton are considerably understudied in the Bay of Bengal (BOB). Here, we investigated community structure and spatial distribution of chromophytic phytoplankton in the BOB by using RuBisCO genes (Form ID rbc L). High throughput sequencing of rbc L genes revealed that diatoms, cyanobacteria (Cyanophyceae), Pelagophyceae, Haptophyceae, Chrysophyceae, Eustigamatophyceae, Xanthophyceae, Cryptophyceae, Dictyochophyceae, and Pinguiophyceae were the most abundant groups recovered in the BOB. Abundances and distribution of diatoms and Pelagophyceae were further verified using quantitative PCR analyses which showed the dominance of these groups near the Equator region ( p < 0.01) where upwelling was likely the source of nutrients. Further, redundancy analysis demonstrated that temperature was an important environmental driver in structuring distributions of Cyanophyceae and dominant chromophytic phytoplankton. Morphological identification and quantification confirmed the dominance of diatoms, and also detected other cyanobacteria and dinoflagellates that were missing in our molecular characterizations. Pearson’s correlations of these morphologically identified phytoplankton with environmental gradients also indicated that nutrients and temperature were key variables shaping community structure. Combination of molecular characterization and morphological identification provided a comprehensive overview of chromophytic phytoplankton. This is the first molecular study of chromophytic phytoplankton accomplished in the BOB, and our results highlight a combination of molecular analysis targeting rbc L genes and microscopic detection in examining phytoplankton composition and diversity.

Distribution of Chromophytic Phytoplankton in the Eddy-Induced Upwelling Region of the West Pacific Ocean Revealed Using rbcL Genes

“…Further, the cosmopolitan occurrence of these groups was also observed in the Sundarbans Mangrove Ecosystem ( Samanta and Bhadury, 2014 ). Our previous study from the Bay of Bengal on the diversity of chromophytic phytoplankton using form ID rbcL gene showed the dominance of these groups in the southern area where wind-driven upwelling was likely the source of nutrients ( Pujari et al, 2019 ). The orientation of Pelagophyceae in the RDA triplot at most of the deeper stations, especially in the upwelling zone, was highly correlated with most of the nutrients recorded during the study ( Figure 7 ).…”

Trophic states regulate assembly processes and network structures of small chromophytic phytoplankton communities in subtropical coastal ecosystem

“…In general, changes in the patterns of these sensitive assemblages were signi cantly associated with eutrophic states, which is consistent with their ecological strategies. As previous study described (Pujari et al, 2019), certain SCP community may be missing due to the bias of the primers used for PCR ampli cation. Besides, the discrepancy of region that make certain SCP discovered in other studies (Bolaños et al, 2020;Irion et al), such as Haptophyceae, Pelagophyceae, and Cyanophyceae, to be inevitably left out in the Beibu Gulf.…”

“…For example, 18S rRNA (for pico-eukaryotes) (Irion et al;Staay et al, 2000) represent useful tools for ecologists to study diversity. Besides, functional gene markers, especially rbcL, which encodes the large subunit (L) of ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) involved carbon assimilation (Nan et al, 2016;Xu and Tabita, 1996), have been extensively used and provide increased resolution for assessments of biodiversity on SCP community across different coastal environments, including the bay of Bengal (Pujari et al, 2019), Western Iberia (Ferreira et al, 2019), Western Mediterranean (Paches et al, 2019) and Northern South China Sea . Although the general patterns underlying variations in biodiversity have been observed across spatial and temporal scales, the response mechanism of SCP to environmental changes in eutrophic seawater are still large unknow.…”

pr2-primers: an 18S rRNA primer database for protists

“…For protists, the 18S rRNA gene appears to be most appropriate as a general marker (Pawlowski et al 2012), although other genes such as rbcL (large unit of the RUBISCO) have been used for specific purposes such as targeting photosynthetic organisms (e.g. Pujari et al 2019). Two variable regions of the 18S rRNA gene have been mostly targeted, V4 and V9: V4 is located in the second quarter of the 18S rRNA gene and V9 at the end pr2-primers database -p. 4 of the 18S rRNA gene, near the ITS (internally transcribed spacer) region.…”