- Dona Paula, Goa, India.
- +91-0832- 2450327
|Abstract Submission No.||ABS-2022-06-0158|
|Title of Abstract||Dynamics and significance of metabolically active bacterioplankton in the frontal regions of the Northeastern Arabian Sea|
|Organisation||CSIR-National Institute of Oceanography|
|Address||CSIR-National Institue of Oceanography|
Dona Paula, Goa, India
|Abstract||Production in the northeastern Arabian Sea (NEAS) during the winter monsoon is supported by the convective mixing process, which injects nutrients from the base of the mixed layer to the surface. This region also harbours many sea surface temperature (SST) fronts and filaments, representing varied biogeochemical conditions. These fronts with congregated biomass are expected to be significant sites of enhanced bacterioplankton activity, which play an important role in the microbial loop. Observations on bacterioplankton were carried out in the NEAS region during early and peak winter monsoon (EWM and PWM) with an emphasis on their physiological state, i.e., metabolically active (HNA; high nucleic acid content) bacteria and metabolically inactive (LNA; low nucleic acid content) bacteria. The results point out that irrespective of seasons, HNA bacteria were dominant in the frontal zones coupled with higher bacterial production (BP), whereas LNA bacteria were abundant in the non-frontal regions. The differentiation in bacterial metabolic types indicate organic matter enrichment in the frontal regions. During the PWM, the nutrient levels increased, resulting in a further increase in HNA bacteria and BP in the frontal regions. Transparent exopolysaccharides (TEP), which are one among the carbohydrates released as exudates during primary production or decaying process, were also higher in the frontal zones, and were inversely related to the total bacterial abundance indicating a fast turnover of the organic matter. The age of the front and the background condition before the formation of the front influences the relative contribution by bacterioplankton to food web dynamics. Thus, evaluation of physiological state of bacteria can be used as a marker for bacterial activity and would be a useful tool in forecasting.|