Spatio-temporal structuring and assembly of abundant and rare bacteria in the benthic compartment of a marginally eutrophic lagoon.

The investigations on ecological processes that structure abundant and rare sub-communities are limited from the benthic compartments of tropical brackish lagoons. We examined the spatial and temporal patterns in benthic bacterial communities of a brackish lagoon; Chilika. Abundant and rare bacteria showed differences in niche specialization but exhibited similar distance-decay patterns. Abundant bacteria were mostly habitat generalists due to their broader niche breadth, environmental response thresholds, and greater functional redundancy. In contrast, rare bacteria were mostly habitat specialists due to their narrow niche breadth, lower environmental response thresholds, and functional redundancy. The spatial patterns in abundant bacteria were largely shaped by stochastic processes (88.7 %, mostly dispersal limitation). In contrast, rare bacteria were mostly structured by deterministic processes (56.4 %, mostly heterogeneous selection). These findings provided a quantitative assessment of the different forces namely spatial, environmental, and biotic that together structured bacterial communities in the benthic compartment of a marginally eutrophic lagoon.