Abstract Chlorophyll-a concentrations were recorded in three oceanographic surveys (GOMEX-4, GOMEX-5, GOMEX-6) during 2015–2018 throughout the Yucatan shelf, southeast Gulf of Mexico (GoM). Such campaigns encompassed the warm-phase, cold-phase, and neutral-phase of El Nino-Southern Oscillation (ENSO), respectively, as well as a progressively increasing upwelling intensification scenario. We undertook the analysis of the Chl-a concentrations in the Yucatan shelf through the multiyear GOMEX series to understand how the interplay between the coastal upwelling, precipitation regime, and wind patterns influence the distribution, magnitude and timing of the phytoplankton biomass. These results suggest that substantial rainfall late summer during ENSO's warm-phase in GOMEX-4 survey improved the coastward Chl-a (1.69 ± 0.07 mg m−3). This pattern could be associated to the increased cold-front activity usually modulated by the wintertime warm-phase of ENSO. The wind-driven mixing during these cold fronts led to water column mix, which contributed to enhance the distinguishing between coastline and marine Chl-a levels. The coastal upwelling pulses depicted a wide-shelf influence over the Chl-a concentration (0.47 ± 0.01 mg m−3 and 0.53 ± 0.03 mg m−3 average concentrations in the marine and coastal areas, respectively). An onshore excursion of cold water masses intermingled with seasonal precipitation traits sustained high nearshore Chl-a in zones already altered by subaqueous freshwater input in the karstified Yucatan seascape (varying within the interval of 1.50–2.76 mg m−3). These results suggest that, similarly to riverine-influenced areas in the northern GoM, warm-phase ENSO episodes have the potential to alter the phytoplankton biomass also in karstified shelves, as the Yucatan platform. This large-scale pattern overlaps processes occurring over a broad spatial and temporal scale, like seasonal rainfall and upwelling, establishing recurrent environmental gradients driving biogeochemical fronts along the seascape. The relationships found allow a better grasp of sound ecologically processes as phytoplankton blooms along the Yucatan shelf, which might be also sensitive to human-driven disturbances.

中文翻译：

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墨西哥湾宽阔低地架海中叶绿素a的时空格局：年际气候格局对浮游植物生物量变化行为的洞察

摘要 2015-2018 年期间，墨西哥湾东南部 (GoM) 的整个尤卡坦大陆架的三项海洋调查 (GOMEX-4、GOMEX-5、GOMEX-6) 中记录了叶绿素-a 浓度。这些活动分别包括厄尔尼诺-南方涛动 (ENSO) 的暖期、冷期和中性期，以及逐渐增加的上升流强化情景。我们通过多年 GOMEX 系列对尤卡坦大陆架中的 Chl-a 浓度进行了分析，以了解沿海上升流、降水状况和风模式之间的相互作用如何影响浮游植物生物量的分布、大小和时间。这些结果表明，在 GOMEX-4 调查中 ENSO 温暖阶段的夏末大量降雨改善了向海岸的 Chl-a (1.69 ± 0.07 mg m-3)。这种模式可能与通常由 ENSO 冬季暖期调节的冷锋活动增加有关。这些冷锋期间的风驱动混合导致水柱混合，这有助于增强海岸线和海洋 Chl-a 水平之间的区别。沿海上升流脉冲描绘了对 Chl-a 浓度的广泛影响（海洋和沿海地区的平均浓度分别为 0.47 ± 0.01 mg m-3 和 0.53 ± 0.03 mg m-3）。冷水团的陆上漂移与季节性降水特征混合在一起，在岩溶化尤卡坦海景（在 1.50–2.76 mg m-3 的区间内变化）已经被水下淡水输入改变的区域中，近岸 Chl-a 维持在高水平。这些结果表明，与 GoM 北部受河流影响的地区类似，暖期 ENSO 事件有可能改变尤卡坦平台等岩溶大陆架中的浮游植物生物量。这种大尺度模式重叠了发生在广泛空间和时间尺度上的过程，如季节性降雨和上升流，建立了驱动沿海景生物地球化学前沿的循环环境梯度。随着尤卡坦大陆架浮游植物大量繁殖，发现的关系可以更好地掌握健全的生态过程，这也可能对人为干扰很敏感。建立循环的环境梯度，驱动沿海景的生物地球化学前沿。随着尤卡坦大陆架浮游植物大量繁殖，发现的关系可以更好地掌握健全的生态过程，这也可能对人为干扰很敏感。建立循环的环境梯度，驱动沿海景的生物地球化学前沿。随着尤卡坦大陆架浮游植物大量繁殖，发现的关系可以更好地掌握健全的生态过程，这也可能对人为干扰很敏感。