Pelagic oxygen minimum zone microbial communities

Abstract

Marine oxygen minimum zones (OMZs) are oxygen-starved regions of the ocean harboring diverse microbial communities that drive biogeochemical processes of global significance, particularly those associated with the nitrogen cycle, with resulting impacts on marine nutrient cycles and the climate system. OMZs appear to be expanding and intensifying due to global climate change. Actual dissolved oxygen concentrations vary among extant OMZs, with some of them being totally anoxic and dominated by anaerobic metabolic processes, others presenting no geochemical signs of anaerobic metabolisms. Despite these overt phenotypic differences, culture-independent molecular studies have identified recurring microbial community composition patterns within OMZs consistent with redox-driven niche partitioning. While the majority of molecular studies have been based on individual marker genes, more recent studies have incorporated community genomic and transcriptomic data sets. Here, we highlight dominant trends emerging from these studies with emphasis on key taxonomic groups implicated in nitrogen, sulfur, and carbon transformations within OMZs.