Meandering development of tidal creeks splits bacterial communities and functional characteristics: Evidence from a field study in Jiangsu Coast, China

Abstract

Tidal creeks are common and important geomorphic features in intertidal zones, which provide a broad range of ecosystem services. The meandering development of tidal creeks can cause a discrepancy in sediment properties between the two banks in tidal creek bends, which affects a few geomorphic and biological processes and seems to be another incentive for the ecological effects of tidal creeks. However, how this discrepancy affects the distribution of bacterial communities in tidal creek bends remains unclear. To this end, we collected sediment samples from a typical tidal creek bend in Jiangsu Coast, China. The bacterial communities were characterized by 16S rRNA gene sequencing and the sediment properties were determined. Results showed that bacterial communities and their functions exhibited significant differences between the convex bank (VB) and the concave bank (CB). Bacterial diversity was higher in VB than in CB, mainly attributed to higher nutrients (TOC and TN), moisture, and finer sediment in VB. The oligotrophic (e.g., Chloroflexi), drought-resistant (e.g., Actinobacteria), and mobile (e.g. Nitrospirae) bacteria had higher abundances in CB. In contrast, bacteria with opposite niche preferences (e.g., Proteobacteria and Acidobacteria) tended to inhabit VB. Network analysis revealed that CB bacterial communities had a higher efficiency of nutrient cycling and carbon uptake but were more vulnerable to environmental disturbances. FAPROTAX results showed that bacterial functions associated with carbon cycles were more abundant in CB, whereas those associated with nitrogen and sulfur cycles were more abundant in VB. Overall, these results demonstrate that the meandering development of tidal creeks splits bacterial communities and functional characteristics in tidal creeks bends. These findings are expected to provide useful information for further understanding and predicting the ecological effects of tidal creeks.