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，选择性地捕杀海洋生物会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，该模型被广泛用于在生态系统背景下评估渔业。食物网状结构通常由胃内容物或大块组织稳定同位素分析决定，这两种方法在分辨率和通用性方面都受到限制。研究人员将改进一种工具，氨基酸化合物特定同位素分析(AA-CSIA)，该工具可广泛适用于量化消费者的综合营养位置(TP)。特定氨基酸的来源和营养氮同位素组成的差异将提供一个明确和综合的跨多个门的营养总磷分数的衡量标准，而无论动物的生理条件或食物网底部的生物地球化学循环如何。AA-CSIA将允许测试从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。本项目有三个目标：1.验证AA-CSIA在不同生理条件下对多个海洋生物门的应用。2.比较AA-CSIA在不同生物地球化学循环体系中的应用。3.开发使用AA-CSIA TP估计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地区不同生物地球化学循环制度的实地研究来测试和改进这种方法。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，将从东热带太平洋、加利福尼亚州沿海和副热带太平洋环流中采集生态系统成分。他们还将测试样品保存对单个AA的同位素组成的影响，以确定这种方法是否可以用于存档的样品。这一工具将使人们能够测试目前用于深入了解渔业捕捞的生态影响的基于生态系统的模型的效力，并提高未来管理海洋资源所需模型的可靠性。除了开发AA-CSIA作为TP指标的目标外，通过该项目获得的信息将提供关于海洋生物摄食行为的重要物种特定生物学数据，这可能对它们对人为压力和气候变化的恢复能力产生影响。该项目将通过提供一种估计营养结构的公正、综合和独立的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，该项目将通过研究生和本科生的参与以及通过K-12课程接触更年轻的学生而产生外展效益。这项研究将有助于更好地了解当地重要鱼类物种以及全球重要虾和濒危海龟的生物学。

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.