Vokhshoori Natasha L, Pugsley Genevieve, Fiechter Jerome, McCarthy Matthew D
Geology Department, St. Lawrence University, Canton, NY, USA.
Ocean Sciences Department, University of California, Santa Cruz, Santa Cruz, CA, USA.
Sci Rep. 2024 Dec 28;14(1):31136. doi: 10.1038/s41598-024-82457-w.
Stable isotopes of carbon (δC) and nitrogen (δN) are commonly employed to reconstruct past change in marine ecosystems and nutrient cycling. However, multiple biogeochemical and physical drivers govern spatiotemporal variability of these isotopic signals, particularly in dynamic coastal systems, complicating interpretation. Here, we coupled a modern multi-year (2010-2019) δC and δN isoscape record from intertidal mussels (Mytilus californianus) with high-resolution ocean model output and satellite chlorophyll-a observations in the California Current System (32°-43° N) to identify major drivers of isotopic variability. Our results show that spatial variations in δC are largely related to primary production, whereas spatial δN variability is driven by water mass mixing. Major isotopic change was also related to ocean climate variability; however, these effects vary regionally. In northern and central California, δN values are predominantly a function of nitrate utilization, whereas in southern California, δN varies due to shifts in water mass composition. In all regions, δC values are driven by productivity, with the largest changes occurring in southern California. Our findings provide novel insight into regional differences in predominant drivers of isotopic variability, and links to modern ocean climate variability. These findings offer crucial information needed for robust interpretations of California Current palaeoceanographic δC and δN records.
碳（δC）和氮（δN）的稳定同位素通常用于重建海洋生态系统和营养物质循环的过去变化。然而，多种生物地球化学和物理驱动因素控制着这些同位素信号的时空变异性，特别是在动态的沿海系统中，这使得解释变得复杂。在这里，我们将来自潮间带贻贝（加州贻贝）的现代多年（2010 - 2019年）δC和δN等景观记录与高分辨率海洋模型输出以及加利福尼亚洋流系统（北纬32° - 43°）的卫星叶绿素-a观测数据相结合，以确定同位素变异性的主要驱动因素。我们的结果表明，δC的空间变化在很大程度上与初级生产力有关，而δN的空间变异性则由水体混合驱动。主要的同位素变化也与海洋气候变化有关；然而，这些影响在区域上有所不同。在加利福尼亚州北部和中部，δN值主要是硝酸盐利用的函数，而在加利福尼亚州南部，δN因水体组成的变化而变化。在所有区域，δC值由生产力驱动，最大的变化发生在加利福尼亚州南部。我们的研究结果为同位素变异性主要驱动因素的区域差异以及与现代海洋气候变化的联系提供了新的见解。这些发现为可靠解释加利福尼亚洋流古海洋学δC和δN记录提供了关键信息。
