Microbial mats are estimated to cover 53,867 ha of the Pilbara coastline in northwest Western Australia. During low tidal periods, these mats enter a state of desiccation and appear barren; however, large spring tides and seasonal storm events trigger rapid physiological recovery, during which the mats deliver a range of important ecosystem services. Here, we use Nitrogen isotope enrichment to investigate rates of nitrogen fixation and nutrient flux in intertidal microbial mats under controlled laboratory conditions, complementing in situ measurements of nutrient stocks and tidal outflows. Nitrogen fixation rates increased significantly with inundation level, and we further influenced by variations in water salinity and temperature. Laboratory-derived nutrient flux data are consistent with elevated nutrient concentrations measured in pooling tidal waters among the mats, where total nitrogen (TN) exceeded 600µg/L. Nutrient concentrations in outgoing tidal waters increased progressively over the course of a falling tide, suggesting active efflux from mat surfaces during inundation. Together, these findings highlight the ecological significance of intertidal microbial mats as dynamic sources of bioavailable nutrients, delivering concentrated pulses to coastal waters during tidal inundation events.