Bacterial dynamics along the west coast of India during the non-monsoon and monsoon season

Variations in bacterial community at Chlorophyll Maximum (C-Max) depths along the west coast of India due to seasonal changes in the primary productivity

“…Bacterial carbon estimated based on abundance value increased significantly during monsoon season and showed a positive correlation with primary productivity measurement (Table 1). These findings align with previous research conducted in the Arabian Sea, which also indicates that the higher levels of phytoplankton growth during the monsoon season have an impact on the bacterial abundance and culturable bacterial communities (Ramaiah et al, 2005; Parab et al, 2022). These studies on the bacterial dynamics in upwelling regions have also shown that a correlation between bacterial productivity and primary productivity exists, underlining the crucial role played by bacteria.…”

“…This indicates that during the upwelling season, the metabolism of microbial communities is particularly active in breaking down complex organic compounds such as carbohydrates, proteins and polysaccharides (Caroppo et al, 2022). However, our previous study based on culturable bacterial populations found that functional activities in the water column during the monsoon season were reduced comparatively than in the non-monsoon season (Parab et al, 2022). Similarly, this study based on metagenomics approaches and predictive gene profiling showed that the heterotrophic metabolic activities were higher during the non-monsoon season (Fig.…”

“…The bacterial counts were also converted to bacterial carbon (BC) using the conversion factor of 20 fg cell -1 (Ducklow et al, 1995) and reported as mg C m -3 . The total plates counts (TPC) of heterotrophic bacteria present in the water samples were also determined based on the spread plate technique on Zobell Marine Agar (ZMA) expressed as colony-forming units (CFUs mL -1 ) (Parab et al, 2022).…”

“…Studies on bacterial communities along the WCI have primarily focused on specific regions, such as the oxygen minimum zones (Bandekar et al, 2018; Fernandes et al, 2020; Lincy and Manohar, 2021), the mud bank regions (Anas et al, 2021; Vijayan et al, 2022) and estuarine habitats (Khandeparker et al, 2017; Kuchi et al, 2021). Studies based on culturable approaches have shown the influence of monsoonal upwelling and higher productivity on the bacterial community structure and functional diversity in the estuarine, coastal and open ocean waters along the WCI (Anas et al, 2021; Vijayan et al, 2022; Parab et al, 2022). Our prior investigation, on the culturable bacterial diversity along the WCI, showed higher bacterial abundance during the monsoon season and with the highest colony-forming units (CFUs) from the C-Max depths (Parab et al, 2022).…”

“…Studies based on culturable approaches have shown the influence of monsoonal upwelling and higher productivity on the bacterial community structure and functional diversity in the estuarine, coastal and open ocean waters along the WCI (Anas et al, 2021; Vijayan et al, 2022; Parab et al, 2022). Our prior investigation, on the culturable bacterial diversity along the WCI, showed higher bacterial abundance during the monsoon season and with the highest colony-forming units (CFUs) from the C-Max depths (Parab et al, 2022). The C-Max, is a prominent feature of tropical marine environments occurring between 20-100 m water depth with maximum primary productivity, due to the optimal physicochemical conditions for the growth of phytoplankton (Cullen, 2015).…”