The Utilization of Shell Oxygen Isotope Analysis to Reconstruct Past El Nino Patterns

内华达大学雷诺分校(UNR)的克里斯托弗·贾兹瓦博士将开展一项研究项目，调查过去厄尔尼诺事件的模式及其对人类住区和生存的影响。该项目将利用考古动物群收集的数据，在更广泛的环境变化背景下追踪厄尔尼诺现象的发生频率，并对人类对当今环境变化的反应产生影响。总体而言，人们预计厄尔尼诺现象更加频繁的时期将对海洋食物资源产生负面影响，包括重要的经济鱼类和贝类物种的种群。在过去，这可能会促使人类生存模式和社会结构发生变化。今天，它可能会影响依赖海洋食品的经济体系。考古遗址和材料是模拟这些系统的独特位置，该项目将利用加州沿海考古环境中的动物材料。此外，该项目旨在完善将考古遗址分配给不同占领季节的方法，这种方法可能会因环境变化而改变。该项目的资金将有助于在联合国大学建立新的人类古生态学和考古测量实验室。这项工作将使研究生和本科生密切参与数据收集的所有阶段，提供实地和实验室分析方面的培训。海峡群岛国家公园内的环境和考古研究将有助于公园保护和清点其宝贵的文化资源。当地丘马什部落的成员将参与该项目的考古实地工作。该项目将使用考古遗址中加州贻贝(Mytilus Calfornianus)贝壳的稳定氧同位素分析来重建贝壳上沉积碳酸盐带时当地海水表面温度的模式。这将使国际和平研究所能够解决三个主要问题：(1)厄尔尼诺事件的频率在过去8,000年中发生了怎样的变化？(2)这些变化对沿海生态系统中的人类住区和生存模式有何影响？(3)用不同的加州贻贝同位素采样技术来确定考古遗址的占用季节的准确性。PI一直在加利福尼亚州圣罗萨岛南部的一个试验场收集现代贻贝贝壳，该试验场是海峡群岛国家公园的一部分，从2015-2017年间每三个月收集一次。这包括2015-2016年的厄尔尼诺冬季。在研究生和本科生的帮助下，将对现代贝壳进行采样和稳定氧同位素分析，以完善观测厄尔尼诺现象和将贝壳分配到收获季节的方法。在夏季发掘贝壳丰富的考古遗址，以及现有的收藏品，将为重建过去的环境模式和人类反应提供样本。尽管厄尔尼诺事件具有全球性影响，但美洲西海岸的海面温度异常尤其强烈，这使得加州成为解决这些问题的理想地点。因此，过去观察到的厄尔尼诺现象频率模式可以用来理解世界各地人类对气候变化的反应。

Dr. Christopher Jazwa of the University of Nevada, Reno (UNR) will conduct a research project to investigate patterns of past El Niño events and their effects on human settlement and subsistence. The project will use data from archaeological faunal collections to trace El Niño frequency within a broader context of environmental variations, with implications for human responses to present-day environment change. In general, there is an expectation that periods with more frequent El Niños will have negative effects on marine food resources, including stocks of economically important fish and shellfish species. In the past, this could have prompted changes in human subsistence patterns and social structures. Today, it could affect economic systems reliant on marine foods. Archaeological sites and materials are uniquely positioned to model these systems and this project will take advantage of faunal materials from well-dated archaeological contexts from coastal California. Furthermore, this project is designed to refine methodologies for assigning archaeological sites to different seasons of occupation, which may shift in response to environmental change. Funding from this project will assist in the development of the new Human Paleoecology and Archaeometry Laboratory at UNR. This work will closely involve graduate and undergraduate students during all stages of data collection, providing training in field and laboratory analyses. Environmental and archaeological research within Channel Islands National Park will assist with the park's missions of preservation and inventorying their valuable cultural resources. Members of the local Chumash tribe will be involved in archaeological fieldwork for this project.This project will use stable oxygen isotopic analysis of California mussel (Mytilus californianus) shells from archaeological sites to reconstruct patterns in local sea surface temperature at the time that bands of shell carbonate were deposited on the shell. This will allow the PI to address three primary questions: (1) How has the frequency of El Niño events varied over the course of the last 8,000 years? (2) What are the effects of these changes on human settlement and subsistence patterns in coastal ecosystems? And (3) with what accuracy can season of occupation of archaeological sites be assigned with different isotopic sampling techniques for California mussels. The PI has been collecting modern mussel shells from a test location on southern Santa Rosa Island, California, part of Channel Islands National Park, at three-month increments from 2015-2017. This included the 2015-2016 El Niño winter. With the assistance of graduate and undergraduate students, the modern shells will be sampled and analyzed for stable oxygen isotopes to refine methodologies for observing El Niño and assigning shells to season of harvest. Excavation of shell-rich archaeological sites during a summer season, along with existing collections, will provide samples to reconstruct past environmental patterns and human responses. Although El Niño events have global effects, anomalies in sea surface temperature are especially strong along the west coast of the Americas, making California an ideal location to address these questions. Therefore, observed patterns of past El Niño frequency can be applied to understand human responses to climate change around the world.