 Abstract | The principle aim of this thesis is to redefine our understanding of the dynamics of microbial communities in groundwater systems. We focused on elucidating fundamental biological parameters in aquifers by determining baseline levels of bacterial and viral abundances and investigating the diversity and metabolic potential of subsurface microbiota. We show that microbial abundances are highly variable in the subsurface. Our data clearly indicates that microbes inhabiting groundwater systems display high levels of small scale heterogeneity. We attribute this microbial heterogeneity to hydrophysicochemical conditions driving niche formation and ecosystem dynamics including top-down and bottom-up processes influencing the composition and dynamics of resident microbial consortia. Recognising environmental heterogeneity and the role of niche partitioning is important in understanding how resident bacterial communities vary as a result of habitat alteration. Our results highlight the importance of heterogeneity, niche specialisation and microbial succession in subsurface environments. We suggest that variability in the abundance and diversity of subsurface microbial communities may be an intrinsic feature of aquifer biology and should be considered when designing groundwater microbial sampling methodologies. Recognition of the highly variable nature of subsurface microbial communities will facilitate a greater understanding of groundwater microbial ecology. |
