Capturing the spatial structure of the benthic microbiome under an intensive aquaculture scenario in Chilean Patagonia.

backgroundIdentifying the microbial taxa that structure assemblages in response to local disturbances along the Chilean Patagonian coast is critical for understanding community reorganization and ecological risk in this vulnerable marine environment. Here, we examined benthic microbial interactions across sixteen sites spanning 42-44°S in the Inner Sea of Chiloé and adjacent fjord systems. Using co-occurrence network analysis, we characterized spatial interaction patterns and identified keystone taxa whose relationships with environmental variables may serve as ecological indicators. The presence of keystone taxa supports the concept of microbial "seed banks," which sustain community stability and ecosystem functionality under stress. Networks revealed structured communities dominated by niche-specialist taxa, consistent with ecological processes of niche differentiation and environmental filtering.

resultsThe benthic environment was found to harbor niche-specialist taxa, including Flavobacteriaceae, Gemmataceae, Humimicrobiaceae, Clostridiaceae, and Sulfurovaceae, typically associated with organic enrichment and anthropogenic influence. These microbial families showed strong correlations with environmental gradients such as nitrate, phosphate, silicate, pH, salinity, and phaeopigments. Alpha-diversity analyses revealed greater microbial richness in FZ compared to the ISC, likely reflecting higher environmental heterogeneity and long-term adaptation to dynamic and fluctuating conditions. Beta-diversity analyses further supported the presence of distinct microbial assemblages between the two zones. Multivariate statistics and co-occurrence network analyses demonstrated that FZ communities display enhanced taxonomic interactions and greater network complexity, suggesting increased ecological stability. In contrast, microbial networks in the ISC exhibited reduced connectivity, potentially indicative of environmental stressors disrupting microbial spatial organization and network resilience. Moreover, the identification of indigenous bacterial isolates provided evidence for the presence of opportunistic host-associated pathogens, highlighting the utility of microbial biomarkers in detecting early ecological responses to human impacts.

conclusionMicrobial co-occurrence patterns in northern Patagonian sediments reveal shifts in community assembly and increased network complexity that may enhance resilience to perturbations. The detection of strains harboring opportunistic pathogen biomarkers highlights risks under intense anthropogenic pressures. Monitoring keystone taxa thus offers early warning of functional decline. Broader spatio-temporal assessments remain essential to clarify microbial dynamics and their implications for ecosystem health and antimicrobial resistance.