Marine Microbial Community Adaptation and Resiliency to Anthropogenic Stresses Through Horizontal Gene Transfer

Horizontal gene transfer (HGT) in prokaryotic lineages is an evolutionary, dynamic mechanism known to promote adaptation to novel habitats by acquisition of genes and alteration of the genetic composition of an organism. The inherent complexity of the microbial species concept exists due to the difficulty involved in quantifying HGT events that results in extensive genome differences even among closely related organisms. In marine ecosystems , HGT leads to an enrichment of microbial populations comprising degradation pathways that enable adaptation to multiple anthropogenic stressors caused by coastal development, oil and gas industry, and aquaculture. Genetic elements such as plasmids, phages and integrons are frequently associated with the dissemination of xenobiotic degradation genes that facilitates microbial adaptation to stress within marine environments. The factors involved in microbial adaptation to stress and their connection to resilience of ecosystems after an anthropogenic disturbance are being increasingly reported and can have implications on coastal recovery and restoration. The increased incidence of metagenomic studies in recent years has also facilitated a better understanding of genetic elements and their contribution to microbial diversity in marine environments. This chapter discusses HGT processes, resistance and resilience patterns found in marine microbial communities along with recent findings about genetic elements that respond to the selective pressures associated with coastal and ocean ecosystems.