Nitrogen cycling in coastal sediment microbial communities with seasonally variable benthic nutrient fluxes

Benthic microbial communities contribute to nitrogen (N) cycling in coastal ecosystems through taxon-specific processes such as anammox, nitrification and N-fixation community attributed pathways denitrification. By measuring the total (DNA-based) active (RNA-based) surface sediment composition abundance activity profiles of key N-cycling genes a semi-enclosed embayment—Port Phillip Bay (PPB), Australia—we show that although relative taxa is comparatively lower close estuary inputs (Hobsons [HB]), capacity for this perform diverse Ncycling higher than sediments isolated from (Central PPB [CPPB]). In HB, seasonal structuring occurred between spring summer, co-occurring with decreases anammox bacteria organic carbon content. No changes were detected nitrifiers or community-based pathway Although no CPPB, displayed within-site variability. These results despite representing smaller fraction impacted (HB) these consistently engage instability not reflective its cycle N coupled nitrification-denitrification but potentially via within community.