In order to assess the relevance of sporadic upwelling events on primary productivity, the availability of nitrogen (N) sources and their uptake by phytoplankton were studied. Incubations of ¹⁵N-enriched samples were performed at 3 depths in 12 stations in San Jorge Gulf (SJG, Patagonia Argentina) aboard of the R/V “Puerto Deseado” during November 2016. Additional coastal stations were sampled to analyze the upwelling event. The total uptake of N sources (ρNO₃^- + ρNH₄⁺) was higher on the surface than in the deep layer. The ρNO₃^- by phytoplankton doubled that of ρNH₄⁺ suggesting SJG acted as a CO₂ sink during the period studied. However, NH₄⁺ played an important role in maintaining primary productivity where NO₃⁻ was low. In most stations, phytoplankton showed a preference for the uptake of the less available N source, likely resulting from adaptation to low nutrient concentrations. However, in the southwestern sector of the gulf, where a wind-induced upwelling occurred, phytoplankton preferred to uptake NO₃⁻, this being the most abundant N source. As a consequence, the integrated primary productivity in the water column of that sector was high. Results suggest that such high productivity was governed by the optimal relationship between the preference and availability of N, established by the presence of elevated NO₃⁻ and low NH₄⁺ ambient concentration. This would be a physiological process regardless of community composition. The new primary productivity generated by upwelling events could be key to feeding the biological resources of the gulf.

为了评估零星上升事件与初级生产力的相关性，研究了氮（N）源的可用性及其对浮游植物的吸收。2016年11月，在“豪门”号R / V上的圣豪尔赫湾（SJG，阿根廷巴塔哥尼亚）的12个站点中，在3个深度进行了¹⁵种富氮样品的培养。2016年11月，对其他沿海站点进行了采样以分析上升事件。N个源的总摄取量（ρNO ₃ ^-  +ρNH ₄ ⁺）中的溶液在表面上比在深层更高。所述ρNO ₃ ^-由浮游植物翻了一番ρNH的₄ ⁺暗示SJG充当CO ₂在研究期间下沉。然而，NH ₄ ⁺起到维持初级生产力其中NO重要作用₃ ^-低。在大多数测站中，浮游植物表现出对较少利用的氮源的吸收的偏好，这可能是由于对低营养物浓度的适应。然而，在海湾，一个风致上升流发生的位置的西南扇区，浮游植物优选NO摄取₃ ^-，这是最丰富的氮源。结果，该部门水部门的综合初级生产力很高。结果表明，这样高的生产率是由N的偏好和可用性之间的最佳关系的约束，通过NO升高存在建立的₃ ^-和低NH ₄ ⁺的环境浓度。无论社区组成如何，这都是一个生理过程。上升事件产生的新的初级生产力可能是喂养海湾生物资源的关键。