Temporal Succession of Phytoplankton Assemblages in a Tidal Creek System of the Sundarbans Mangroves: An Integrated Approach

Abstract

Sundarbans, the world's largest mangrove ecosystem, is unique and biologically diverse. A study was undertaken to track temporal succession of phytoplankton assemblages at the generic level (≥10 µm) encompassing 31 weeks of sampling (June 2010–May 2011) in Sundarbans based on microscopy and hydrological measurements. As part of this study, amplification and sequencing of type ID rbcL subunit of RuBisCO enzyme were also applied to infer chromophytic algal groups (≤10 µm size) from one of the study points. We report the presence of 43 genera of Bacillariophyta, in addition to other phytoplankton groups, based on microscopy. Phytoplankton cell abundance, which was highest in winter and spring, ranged between 300 and 27,500 cells/L during this study. Cell biovolume varied between winter of 2010 (90–35281.04 µm3) and spring-summer of 2011 (52–33962.24 µm3). Winter supported large chain forming diatoms, while spring supported small sized diatoms, followed by other algal groups in summer. The clone library approach showed dominance of Bacillariophyta-like sequences, in addition to Cryptophyta-, Haptophyta-, Pelagophyta-, and Eustigmatophyta-like sequences which were detected for the first time highlighting their importance in mangrove ecosystem. This study clearly shows that a combination of microscopy and molecular tools can improve understanding of phytoplankton assemblages in mangrove environments.

Analysis of diversity of chromophytic phytoplankton in a mangrove ecosystem using rbcL gene sequencing

“…Additionally, using microscopy it has been shown by us that bulk of the assemblages in terms of cell abundance and diversity across the study sites were constituted by diatoms and representation of nondiatom chromophytic algal groups were very low in terms of cell number (Bhattacharjee et al. ).…”

“…Since one of the objectives of this study was to detect nondiatom chromophytic algal groups from the Sundarbans and we could successfully detect the same, hence preferential amplification of dominant templates by rbcL primers if any did not significantly alter or limit the detection of nondiatom chromophytic algal groups in Sundarbans assemblages. Additionally, using microscopy it has been shown by us that bulk SUNDARBANS CHROMOPHYTIC PHYTOPLANKTON MOLECULAR DIVERSITY of the assemblages in terms of cell abundance and diversity across the study sites were constituted by diatoms and representation of nondiatom chromophytic algal groups were very low in terms of cell number (Bhattacharjee et al 2013).…”

“…The diversity and richness calculations of the rbcL clone libraries indicate that overall richness of the chromophytic phytoplankton assemblages from the study sites were higher when compared to microscopy based approaches from the region. In a separate study, we encountered 46 genera of phytoplankton (41 genera of Bacillariophyceae and five genera of Dinophyceae) based on microscopy from March 2010 to April 2011 from the same study sites (Bhattacharjee et al 2013). This clearly indicates that the resolution of molecular approaches to understand chromophytic phytoplankton community structure at the functional level was significantly higher and also helped toward unraveling the unexplored diversity (e.g., detection of groups such as Haptophyceae and Pelagophyceae) for the first time from any Asian mangrove environment.…”

Exploring biogeographic patterns of bacterioplankton communities across global estuaries

“…It has been also reported in the literature that Synechococcus population have the ability to tolerate low oxygen in water (Nogales, Lanfranconi, Piña‐Villalonga, & Bosch, ). In the Mooriganga estuary of Sundarbans, Synechococcous populations are present throughout the year (Singh & Bhadury, ) even when dissolved oxygen concentration has been found to be low during summer (Bhattacharjee et al, ).…”

“…Sagar Island is the biggest island of Indian Sundarbans and marks the westernmost part of this ecoregion. A predesignated station named as Stn3 (Mooriganga) (21° 40ʹ 40.6ʺ N, 88° 09ʹ 19.2ʺ E) which is part of the Sundarbans Biological Observatory Time Series (SBOTS) monitored since 2010 has been considered in this study (Bhattacharjee, Samanta, Danda, & Bhadury, ; Choudhury, Das, Philip, & Bhadury, ; Samanta & Bhadury, ). Huge freshwater from the Mooriganga estuary and diurnal tidal influx of coastal water from the Bay of Bengal gives rise to typical estuarine conditions in this station.…”