Marine environmental pollution stress detection through direct viable counts of bacteria.

Direct viable counts (DVC) of bacteria were quantified from polluted and relatively less/non-polluted coastal locations during different seasons to assess whether they can be routinely monitored for an understanding of environmental stress(es) that may impede the full functioning of bacterial communities in situ. Most notably, DVC were quite low during pre-monsoon (March-May) in pollution-affected locations when compared to relatively less/non-polluted ones. In contrast, their abundance was significantly higher (up to or > 10%) suggesting a substantially higher microbial activity (thus, a larger turnover of organic matter) during monsoon (June-September) and post-monsoon (October-February) even in pollution-affected locations. The ease of reliably measuring DVC was useful in realising decreased metabolic functioning of bacteria during pre-monsoon, a season where dispersion of land discharges/effluents is much lower. From laboratory and field analyses of this study it is ascertained that DVC are direct indices of potential bacterial metabolic activity, reliable for sensing metabolic stress experienced by bacterial communities in situ and can be useful for evaluating risks in marine environment through human (industrial) activities.