Bacterioplankton abundance and community structure during post-monsoon in mangrove dominated estuaries of the Indian Sundarbans; An insight to biogeochemical processes. (30th September 2020)

• Record Type: Journal Article
• Authors: Mukherjee, Rishmita; Dutta, Manab Kumar; Sanyal, Prasun; Bhadury, Punyasloke; Mukhopadhyay, Sandip Kumar
• Is Part Of: Estuarine, coastal and shelf science. Volume 243(2020)
• Publication Date: 2020-09-30
• Subjects: Mangroves -- Bacterioplankton -- Abundance -- Biogeochemistry -- Community composition; Estuarine oceanography -- Periodicals; Coasts -- Periodicals; Estuarine biology -- Periodicals; Seashore biology -- Periodicals; Coasts; Estuarine biology; Estuarine oceanography; Seashore biology; Periodicals; 551.461805
• DOI: 10.1016/j.ecss.2020.106895
• Languages: English
• ISSNs: 0272-7714

Abstract

Abstract: Bacterioplankton abundances in three major estuaries of the Indian Sundarbans (Saptamukhi, Thakuran and Matla) were determined by flow cytometry and fluorescence microscopy in a post-monsoonal study followed by microbial community composition (16S rRNA clone library), during the period 2012–2016. All three estuaries were oxygenated and meso - to polyhaline. They had similar levels of dissolved inorganic carbon and nutrients and were net heterotrophic, as evidenced by net negative community productivity. Mean post-monsoon bacterioplankton abundances (x 10 9 cells L −1 ) in these estuaries were: Saptamukhi (1.30 ± 0.78 × 10 9 cells L −1 ); Matla (1.38 ± 1.34 × 10 9 cells L −1 ); Thakuran, (0.92 ± 0.46 × 10 9 cells L 1 ). Bacterioplankton abundance was associated with water temperature coupled with dissolved inorganic nutrients and carbonate parameters. Highest abundances were at the most upstream sites in the Saptamukhi and Matla estuaries, while a mid-estuarine peak was evident in Thakuran. In the Saptamukhi and Thakuran the bacterioplankton was dominated by Proteobacteria (mostly Deltaproteobacteria ), with a contribution from Bacteroidetes in the Saptamukhi and from Cyanobacteria and Actinobacteria in the Thakuran. Despite the oxygenated nature of these estuaries, clones resembling the sulfate reducer Desulfovibrio sp. were detected, and this could be a consequence of anoxic pore water exchange across the sediment-water interface. Sulfate reduction may thus be an important pathway for carbon metabolism in these ecosystems. Highlights: During post-monsoon (2012-2016) three major estuaries of Indian Sundarbans were well oxygenated and well mixed. Estuaries exhibited analogous levels of dissolved nutrients and carbonate parameters. Bacterioplankton abundance of three estuaries varied from 0.92 ± 0.46 × 10 9 cells L -1 to 1.38 ± 1.34 × 10 9 cells L -1 . Bacterioplankton abundance was controlled by multiple physico-chemical factors (such as water temperature, pCO2 ) etc. Bacterioplankton community contained strains associated with sulfate reduction, such as Desulfovibrio sp. Anaerobic microbes in well oxygenated estuaries indicate role of exchange of pore-water in shaping the microbiota.