Instituto Politécnico Nacional- Centro Interdisciplinario de Ciencias Marinas, Departamento de Oceanología, Av. Instituto Politécnico Nacional s/n, Col. Playa Palo de Santa Rita, C.P. 23096 La Paz, Baja California Sur, Mexico.
Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE)-Unidad La Paz. Laboratorio de Macroecología Marina, C.P. 23050 La Paz, Baja California Sur, Mexico.
Sci Total Environ. 2024 Jan 20;909:168497. doi: 10.1016/j.scitotenv.2023.168497. Epub 2023 Nov 15.
This research analyzes for the first time in the Pacific Tropical-Subtropical Convergence off Mexico during June 2010 the relationships among the δC and δN signal distribution in the bulk zooplankton, water masses, and mesoscale structures. The environmental analysis showed that the California Current Water (CCW) and Transitional Water (TrW) converge where the 22 °C isotherm and 34.6 g kg isohaline were observed (22°N). Two cyclonic eddies were detected: one in CCW at 24°N about 70 km in diameter, the other one located in TrW at 21°N with 150 km in diameter. A cluster analysis defined three zooplankton isoscapes with significant differences. Isoscape 1, immerses in CCW - the lowest δC (-22.37 ± 0.89 ‰) and δN (9.89 ± 1.32 ‰) - showed temperature (19.86 ± 1.97 °C), salinity (34.08 ± 0.37 g kg) values, the deepest thermocline (77.93 ± 25.51 m) and oxygen minimum zone (164.78 ± 44.96 m). The CCW was relatively oligotrophic without important mesoscale features in the sampled time within the sampled area. Isoscape 2, a cyclonic eddy in CCW - relatively enriched zooplankton δC values (-16.78 ± 1.95 ‰) due to the entry of enriched coastal biota- reflected in high chlorophyll a and subsequently assimilated into zooplankton tissues. Isoscape 3, a cyclonic eddy immerses in TrW - the highest δN (13.14 ± 1.60 ‰), salinity (34.76 ± 0.19 g kg) and temperature (19.90 ± 2.27 °C) values and shallowest thermocline (32.27 ± 18.63 m), and oxygen minimum zone (66.82 ± 37.68 m) in depth. Likely, this N-enriched recycled nitrate was pumped from the deoxygenated subsurface to the surface, reflected in the zooplankton bulks. The results showed that the isotopic signals in bulk zooplankton may be a good water mass and mesoscale activity tracer.
本研究首次分析了 2010 年 6 月在墨西哥热带-亚热带辐合带太平洋海域的大型浮游动物、水体和中尺度结构中的δC 和 δN 信号分布之间的关系。环境分析表明，在 22°C 等温水线和 34.6 g kg 等盐度线交汇的地方，存在着加利福尼亚海流水 (CCW) 和过渡水 (TrW)（22°N）。检测到两个气旋式漩涡：一个在 CCW 中，位于 24°N，直径约 70 公里，另一个位于 TrW 中，直径为 150 公里。聚类分析定义了三个具有显著差异的浮游动物同位素景观。同位素景观 1 位于 CCW 中，δC 值最低（-22.37±0.89‰），δN 值（9.89±1.32‰）最低，水温（19.86±1.97°C）、盐度（34.08±0.37 g kg）值最高，温跃层最深（77.93±25.51 m），含氧最小值区最深（164.78±44.96 m）。CCW 相对贫营养，在采样期间，采样区域内没有重要的中尺度特征。同位素景观 2 是一个位于 CCW 的气旋式漩涡，由于富含沿海生物的进入，浮游动物 δC 值相对较高（-16.78±1.95‰），反映在高叶绿素 a 上，随后被浮游动物组织同化。同位素景观 3 位于 TrW 中的一个气旋式漩涡，δN 值最高（13.14±1.60‰），盐度（34.76±0.19 g kg）和温度（19.90±2.27°C）值最低，温跃层最浅（32.27±18.63 m），含氧最小值区最深（66.82±37.68 m）。很可能，这种富氮的再循环硝酸盐是从缺氧的次表层泵送到表面的，这反映在浮游动物的总量中。结果表明，大型浮游动物的同位素信号可能是一种很好的水体和中尺度活动示踪剂。
