Americas Program Dissertation Enhancement: The Importance of Colorado River Flow to Endemic Fish of the Northern Gulf of California: Evidence from Stable Isotopes in Fish Otoliths

0323139 FlessaThis美洲计划论文增强项目将支持论文论文研究由克尔斯滕·罗威尔博士的监督下。 这项研究将与墨西哥恩塞纳达下加利福尼亚自治大学的Conal True博士合作，旨在通过研究大多数鱼类头部（耳石）中发现的小结构中的同位素变化，将氧和碳含量与水和食物联系起来。 在上游水坝和引水之前，科罗拉多河对加州北方海湾的栖息地产生了重大影响。 据推测，河流整治和蓄水改变了河口生境，对两种特有鱼类产生了负面影响。 本研究的具体目标包括：1）通过耳石中氧和碳的稳定同位素记录的大坝前和大坝后的环境条件的比较; 2）大坝前和大坝后两种鱼类标本的生长率的比较;和3）大坝前和大坝后两种鱼类标本的栖息地，产卵时间和频率的比较。通过使用存储在鱼耳石中的氧和碳的稳定同位素，生长增量和产卵频率的形式的基线数据，本研究将显着提高女研究生的论文研究，启动与墨西哥同事的国际合作，并提供渔业管理人员的技术来检测和测量食物网和栖息地的长期历史变化。 美国国家科学基金会的美洲项目和地理与区域科学项目共同支持这一论文增强项目。

0323139FlessaThis Americas Program thesis enhancement project will support thesis dissertation research by Kirsten Rowell under the supervision of Dr. Karl Flessa of the University of Arizona. The research, which will involve collaboration with Dr. Conal True of the Universidad Autonoma de Baja California, Ensenada, Mexico, aims to correlate oxygen and carbon content with water and food by studying their isotopic variation in small structures found in the head of most fish (otoliths). Before upstream dams and water diversion, the Colorado River was a major influence on northern Gulf of California habitats. River regulation and impoundment are hypothesized to have altered the estuarine habitat, negatively affecting two endemic fish types. Specific goals of this study include: 1) comparison of the pre-dam and post-dam environmental conditions recorded by the stable isotopes of oxygen and carbon in the otoliths; 2) comparison of growth rates in pre-dam and post-dam specimens of both fish species; and 3) comparison of the habitat, timing and frequency of spawning in pre-dam and post-dam specimens of the two species of fish. By using baseline data stored in fish otoliths in the forms of stable isotopes of oxygen and carbon, growth increments, and spawning frequencies, this study will significantly enhance the dissertation research of a female graduate student, initiate international collaboration with a Mexican colleague, and provide fisheries managers with techniques to detect and measure long-term historical changes in food webs and habitats. The Americas Program and the Geography and Regional Science Program of NSF are jointly supporting this thesis enhancement project.