Habitat fragmentation may amplify antibiotic resistance genes (ARGs), yet the ecological pathways linking landscape patterns to host resistomes in intertidal systems remain unclear. Macrobenthic organisms as potential reservoirs and dispersal nodes are ideal models. Focusing on the horseshoe crab (Tachypleus tridentatus), a food web hub and habitat indicator, we integrated landscape metrics, metagenomics, and path modeling (PLS-PM) to examine, across fragmented habitats, links among sediment physicochemistry, larval diet, gut microbiota, mobile genetic elements (MGEs), and ARGs. Results revealed that more fragmented habitats promoted individuals with higher ARG abundance and diversity, alongside stronger MGE enrichment and increased ARG-MGE co-occurrence, indicating enhanced mobility potential. Fragmentation also coincided with greater dietary diversity but higher among-individual convergence, selective assembly of gut microbiota with higher diversity, and tight ARG-MGE association. PLS-PM supported a diet-gut microbiota-MGE-ARG cascade, while the direct effects of sediment chemistry were not significant. Attributing ARG hosts at the MAG level, Enterobacteriaceae and Vibrionaceae dominated ARG abundance and enrichment, indicating lineage selectivity. Multidrug and polymyxin resistance was most prominent. These findings identify key AMR risk pathways and inform priority interventions for T. tridentatus and habitat conservation. The developed assessment framework is scalable and offers a paradigm for One Health management in mudflat systems.
Chen et al. (Mon,) studied this question.