Collaborative Research: CAMEO 2009 - A novel tool for validating trophic position estimates in ecosystem-based fisheries models

越来越多的证据表明，选择性清除海洋生物可以导致海洋食物网的重组。营养结构是质量平衡模型的核心组成部分，质量平衡模型是广泛用于评估生态系统背景下渔业的工具。食物网结构通常由胃内容物或大块组织稳定同位素分析确定，这两者在分辨率和多功能性方面都受到限制。研究人员将改进一种工具，即氨基酸化合物特异性同位素分析（AA-CSIA），该工具可广泛应用于量化消费者的时间积分营养位置（TP）。特定氨基酸的来源和营养性氮同位素组成的差异将提供跨多个门的部分营养性总磷的明确且综合的测量，无论动物的生理状况或食物网基础的生物地球化学循环如何。 AA-CSIA 将允许测试基于生态系统的模型得出的营养位置估计的有效性，并促进这些模型演变为决策支持工具。该项目有三个目标： 1. 验证 AA-CSIA 在不同生理条件下在多个海洋门中的应用。 2. 通过对比生物地球化学循环方案来比较 AA-CSIA 跨系统的应用。 3. 开发使用 AA-CSIA TP 估算来验证已开发生态系统的营养模型。 研究人员将结合实验室饲养实验和跨不同生物地球化学循环机制的地区的现场研究来测试和完善该方法。他们将确定 AA-CSIA 方法在对照研究中评估的各种海洋生物中的适用性。随后，将从热带太平洋东部、加利福尼亚沿海和副热带太平洋环流中采集生态系统组成部分。他们还将测试样品保存对单个 AA 同位素组成的影响，以确定该方法是否可用于存档样品。该工具将能够测​​试目前使用的基于生态系统的模型的有效性，以深入了解渔业捕捞的生态影响，并提高管理海洋资源所需的未来模型的可靠性。除了开发 AA-CSIA 用作 TP 指标的目标之外，通过该项目获得的信息还将提供有关海洋生物摄食行为的重要物种特定生物数据，这可能对其对人为压力和气候变化的恢复力产生影响。该项目将通过提供公正、综合和独立的营养结构估计方法以及验证现有基于生态系统的模型输出和预测的方法，直接应用于评估渔业的生态系统影响。此外，该项目还将通过研究生和本科生的参与以及通过 K-12 项目让年轻学生接触而带来外展效益。这项研究将有助于更好地了解当地重要鱼类以及全球重要虾和濒临灭绝的海龟的生物学。

Evidence increasingly demonstrates that selective removal of marine life can induce restructuring of marine food webs. Trophic structure is the central component of mass balance models, widely used tools to evaluate fisheries in an ecosystem context. Food web structure is commonly determined by stomach contents or by bulk tissue stable isotope analyses, both of which are limited in terms of resolution and versatility. The investigators will refine a tool, Amino Acid Compound-Specific Isotopic Analyses (AA-CSIA), which can be broadly applicable for quantifying the time-integrated trophic position (TP) of consumers. Differences in source and trophic nitrogen isotopic composition for specific amino acids will provide an unambiguous and integrated measure of fractional trophic TP across multiple phyla, regardless of an animal's physiological condition or of the biogeochemical cycling at the base of the food web. AA-CSIA will allow testing of the efficacy of trophic position estimates derived from ecosystem-based models and promote the evolution of these models into decision-support tools. This project has three goals: 1. To validate the application of AA-CSIA across multiple marine phyla under differing physiological conditions. 2. To compare the application of AA-CSIA across systems with contrasting biogeochemical cycling regimes. 3. To develop the use of AA-CSIA TP estimates for validating trophic models of exploited ecosystems. The investigators will test and refine the approach using a combination of laboratory feeding experiments and field studies across regions with differing biogeochemical cycling regimes. They will determine the applicability of the AA-CSIA approach in a variety of marine organisms assessed in controlled studies. Subsequently, ecosystem components will be sampled from the eastern tropical Pacific, coastal California and the subtropical Pacific gyre. They will also test the effects of sample preservation on the isotopic composition of individual AA to determine whether the approach can be used on archived samples. This tool will allow testing of the efficacy of ecosystem-based models currently used to gain insight into the ecological effects of fisheries removals and improve the reliability of future models required to manage marine resources. In addition to the goal of developing AA-CSIA for use as a TP indicator, the information obtained through this project will provide important species-specific biological data on the feeding behavior of marine organisms that could have implications for their resilience to anthropogenic pressures and climate change.This project will have direct application to evaluating ecosystem effects of fisheries by providing an unbiased, integrated and independent approach toestimating trophic structure, and a method by which to validate existing ecosystem-based model outputs and predictions. In addition, the project will have outreach benefits through the involvement of graduate and undergraduate students, and exposure of younger students through K-12 programs. This research will contribute to the greater understanding of the biology of locally important fish species as well as globally important shrimp and endangered marine turtles.