Dissertation Research: Evaluating changes in food web linkages and mercury bioaccumulation by top predators in response to the removal of an introduced predator

该项目将调查去除北部湖泊中广泛引入的非本地捕食者对食物网的影响。50多年前，小口鲈鱼被引入研究湖泊，导致本地猎物鱼的丰度减少，食物网发生了重大变化。2000年实施的小嘴鲈鱼清除计划增加了本地猎物鱼类的丰度，恢复了食物网的联系（使用鱼组织中的稳定同位素测量），并改变了顶级捕食者体内的汞浓度。该项目的目标是：1)量化湖泊鱼类群落、食物网联系和汞生物积累的变化，这些变化是对正在进行的清除工作的响应；2)评估导致这些变化的过程；3)评估作为管理湖泊生态系统工具的捕食者清除/控制。关于大规模捕食者操纵的影响的信息有限，这通常是为了在北美湖泊提供休闲钓鱼机会而实施的。本研究的结果将为以下方面提供改进的能力：1)使用鱼类组织中的稳定同位素作为湖泊恢复的度量标准；2)了解和改变运动鱼类中汞积累的过程；3)实施管理方法来恢复受优势非本地物种影响的本地鱼类群落。

This project will investigate the food web effects of removing a widely introduced non-native predator found in northern lakes. Smallmouth bass were introduced into the study lake more than 50 years ago, which resulted in reduced abundance of native prey fish and major food web changes. A smallmouth bass removal program implemented in 2000 resulted in increased native prey fish abundance, restoration of food web linkages (measured using stable isotopes in fish tissue), and changes in mercury concentrations in top predators. Project goals are to: 1) quantify changes in lake fish communities, food web linkages and mercury bioaccumulation that have occurred in response to the ongoing removal effort, 2) evaluate the processes responsible for these changes, 3) and evaluate predator removal/control as a tool to manage lake ecosystems.Limited information is available regarding the effects of large-scale predator manipulations, which are commonly implemented to provide recreational angling opportunities in North American lakes. Results from this study will provide an improved ability to: 1) use stable isotopes in fish tissue as a metric for lake restoration, 2) understand and alter processes responsible for mercury accumulation in sport fish, and 3) implement management approaches to restore native fish communities impacted by dominant non-native species.