Analysis of microbial communities in the habitat of the gull-billed tern (Gelochelidon nilotica) within the Chenier Island Wetland National Nature Reserve

The Binzhou Chenier Island and Wetland National Nature Reserve is one of the best-preserved and largest chenier systems in the world, with its unique ecological environment providing high-quality habitats and breeding grounds for numerous bird species. As a typical dominant species in this region, the Gull-billed Tern ( Gelochelidon nilotica ) can serve as an indicator species reflecting changes in the wetland ecological environment. To elucidate the impacts of gull-billed tern activities and nest microhabitats on the microbial communities in their environments, and to clarify the connectivity patterns and functional profiles of microbial communities across multiple environmental media, this study investigated nest sediments (ZOC), surrounding soils (ZOT), water (ZOL), and aquatic plants (ZOS) using high-throughput sequencing combined with multivariate statistical analysis to characterize the microbial community structure and functional traits of these four media. The results showed that microbial community differentiation in the study area was primarily driven by habitat filtering, while also being regulated by gull-billed tern activities. Water acted as a key barrier restricting cross-medium microbial dispersal, leading to a clear delineation of communities into terrestrial and aquatic clusters. The microbial community structures of nest sediments and adjacent soils were highly similar, with only weak connections observed between different media, suggesting that bird activities exert a limited influence on microbial communities. Functional pathways across different habitats were generally conserved and inter group functional differentiation matched the niche requirements of each microhabitat. This study clarifies the limited but directed regulatory role of waterbirds in the microbial connectivity between terrestrial and aquatic ecosystems and reveals the assembly mechanisms and functional adaptation patterns of microbial communities across multiple media. These findings provide important microbiological insights for understanding material cycling, maintaining ecosystem health, and supporting the scientific conservation and management of waterbird habitats in the Bin zhou Chenier Island Wetland. It should be noted that the conclusions of this study are based only on taxonomically assignable taxa and therefore represent a conservative interpretation. Future research incorporating bird-related samples will further deepen the understanding of the underlying mechanisms.