Abstract
AbstractTidal hydrodynamics drive the groundwater-seawater exchange and shifts in microbiota structure in the coastal zone. However, how microbiota structure responds to periodic tidal fluctuations and anthropogenic disturbance is seldom evaluated in the intertidal groundwater-surface water (GW-SW) continuum, although it affects microbially driven biogeochemical cycles and ecosystem function therein. Here, we resolved the high-resolution spatiotemporal dynamics and assembly mechanisms along a GW-SW continuum in the natural tidal creek. Our results revealed an evident rhythmic pattern of microbiota structure in response to daily and monthly tidal fluctuations in intertidal surface water. The similarity in archaeal community structures among groundwater and ebb-tide surface water demonstrated archaeal transport through groundwater discharge, whereas multi-source transport mechanisms led to the occurrence of unique bacterial biota in ebb-tide water. Mechanistically, homogeneous selection (58.6%-69.3%) dominated microbiota assembly patterns in the intertidal GW-SW continuum, while biotic interactions were weaker in the groundwater microbiota than the surface water microbiota. Compared with the natural tidal creek, we found that microbiota biodiversity and community succession in intertidal groundwater under anthropogenic-induced terrestrial nutrient inputs and weakened tidal fluctuations were primarily controlled by increased dispersal limitation and consequent weakening of homogeneous selection, as well as enhanced biotic interactions. Overall, this study sheds light on the ecological rules guiding water microbiota assembly in the coastal transition zones and highlights periodic hydrodynamic and anthropogenic disturbances as prominent influencing factors of the microbiota structure, as well as the potential for enhancing coastal monitoring initiatives by incorporating only a few rhythmic but critical key microbial observations.
Publisher
Cold Spring Harbor Laboratory