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 10⁹ cells L⁻¹) in these estuaries were: Saptamukhi (1.30 ± 0.78 × 10⁹ cells L⁻¹); Matla (1.38 ± 1.34 × 10⁹ cells L⁻¹); Thakuran, (0.92 ± 0.46 × 10⁹ cells L¹). 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.

在季风后研究中，通过流式细胞仪和荧光显微镜，在2012-2016年期间，通过流式细胞仪和荧光显微镜确定了印度桑达班河（Saptamukhi，Thakuran和Matla）三个主要河口的细菌浮游细菌丰度，随后进行了微生物群落组成（16S rRNA克隆文库）的测定。这三个河口都被充氧并中消旋成多卤水。它们具有相似水平的溶解性无机碳和养分，并且是净异养的，这由净负群落生产力证明。在这些河口中，季风后的平均浮游细菌丰度（x 10 ^9个 细胞L ^-1）为：Saptamukhi（1.30±0.78×10 ^9个 细胞L ^-1）；Matla（1.38±1.34×10 ^9个 单元格L ^-1）; 塔库兰（0.92±0.46×10 ^9个 细胞L ¹）。浮游细菌的丰度与水温，溶解的无机养分和碳酸盐参数有关。丰度最高的是Saptamukhi和Matla河口的最上游站点，而塔库兰河口的峰值明显。在Saptamukhi和Thakuran中，浮游细菌以变形杆菌（多数为Deltaproteobacteria）为主，Saptamukhi中的拟杆菌属以及Thakuran的蓝细菌和放线菌起作用。尽管这些河口具有氧化性质，但克隆类似于硫酸盐还原剂Desulfovibriosp。被检测到，这可能是沉积物-水界面上缺氧孔隙水交换的结果。因此，硫酸盐还原可能是这些生态系统中碳代谢的重要途径。