Regulation of Nitrate Uptake by the Seagrass Zostera marina During Upwelling

摘要: Prolonged nitrogen (N) fertilization can impact seagrass survival and productivity; however, the effects of N enrichment pulses (e.g., upwelling or sediment resuspension) remain poorly understood. This study examined short-term (1 h) pulsing nitrate (NO3−) enrichment, simulating an event, on dissolved inorganic carbon (DIC) NO3− uptake capacities, critical in controlling eelgrass productivity. Zostera marina dominates submerged vegetation coastal lagoons influenced by California Current system. Laboratory incubations were conducted winter (non-upwelling) spring (upwelling) with shoots collected from San Quintin Bay meadows, Baja California, Mexico, differentially exposed to upwelled NO3−. Results suggest that stimulated DIC uptake in winter, reflecting close relationship between metabolism assimilation. Eelgrass showed reduced incorporation in spring; neither nor photosynthesis increased when high Saturation at lower ambient concentrations may be interpreted as a physiological strategy restrict metabolically costly incorporation during upwelling; this regulation strongly contrasts apparently full exploitation nutrient seaweeds also dominant within bay, indicated previous works. Despite their uptake, meadows near bay mouth acquire rates up 4.2 mmol N m−2 day−1. represents non-trivial water column removal compared estimated oceanic supply (~ 7.1 mmol m−2 day−1) upwelling, highlighting importance Z. beds lagoonal N-budget.