SAMEA14075404 ERS11678633 uncultured Bacteroidetes bacterium This sample represents a Third Party Annotation (TPA) Metagenome-Assembled Genome (MAG) assembled from the metagenomic run ERR864073 of study ERP010213. EBI Generic Generic.1.0 ERC000047 2023-01-03 2023-01-03 SAMEA14075404 EBI European Bioinformatics Institute 2023-01-03T00:32:23Z 2023-01-03T00:32:23Z public ERR864073_bin.76_CONCOCT_v1.1_MAG Multiple fragments where gaps span repetitive regions. Presence of the 23S, 16S, and 5S rRNA genes and at least 18 tRNAs metaSPAdes version 3.10.139 Default CONCOCT v1.1 EMG broker account, EMBL-EBI 2010-08-07 99.46 CheckM 2.64 Environmental Aquatic Marine USA 46.233 -124.16 metagenome-assembled genome marine metagenome marine metagenome Microbial communities mediate the biogeochemical cycles that drive ecosystems, and it is important to understand how these communities are affected by changing environmental conditions, especially in complex coastal zones. As fresh and marine waters mix in estuaries and river plumes, the salinity, temperature, and nutrient gradients that are generated strongly influence bacterioplankton community structure, yet, a parallel shift in functional diversity has not been described. Metagenomic and metatranscriptomic analyses were conducted on five water samples spanning the salinity gradient of the Columbia River coastal margin, including river, estuary, plume, and ocean, in August 2010. Samples were pre-filtered through 3 μm filters and collected on 0.2 μm filters, thus results were focused on changes among free-living microbial communities. Results from metagenomic 16S rRNA sequences showed taxonomically distinct bacterial communities in river, estuary, and coastal ocean. Despite the strong salinity gradient observed over sampling locations (0 to 33), the functional gene profiles in the metagenomes were very similar from river to ocean with an average similarity of 82%. The metatranscriptomes, however, were an average of only 31% similar. We observed shifts from river to ocean in the abundance of genes encoding specific functions, such as catabolic pathways, osmoregulators, and metal transporters. Additionally, genes specifying both bacterial oxygenic and anoxygenic photosynthesis were highly abundant and expressed in the estuary and plume. Denitrification genes were found throughout the Columbia River coastal margin, and most highly expressed in the estuary. Across a river to ocean gradient, the free-living microbial community followed three different patterns of diversity: 1) the taxonomy of the community shifted strongly with salinity, 2) metabolic potential was highly similar across samples, with only small differences in functional gene abundance from river to ocean, and 3) gene expression was highly variable and generally was independent of changes in salinity. SAMEA3355528 ERR864073_bin.76_CONCOCT_v1.1_MAG uncultured Bacteroidetes bacterium Illumina HiSeq 1000 multi-marker approach