Predicting dissolved oxygen concentrations in Lake Trout lakes: Developing new tools for a multiple-stressor world

加拿大的鲑湖是一种稀有而宝贵的自然资源，无论是在经济方面(仅在安大略省，垂钓者在与休闲钓鱼相关的商品和服务上花费约17亿美元，湖鲑鱼是许多垂钓者的首选物种)和生态条件。然而，湖泊鲑鱼种群正日益受到多种环境压力的威胁(如过度捕捞、与引进物种的竞争、营养负荷)，并增加了气候变暖加速的“威胁倍增”。人们越来越担心，由于氧气枯竭，许多鲑湖深水的栖息地质量正在下降。此外，新的证据表明，在营养物质输入没有增加的湖泊中，甚至在磷输入或湖泊营养物质浓度随着时间的推移而减少的湖泊中，深水氧浓度可能正在下降，这创造了“营养物质增加，深海减少”的例外情况 氧气范例“。这一点特别令人关切，因为目前的资源管理方法是以这一重大假设为前提的，因此在一个多个应激源的世界中是有问题的，特别是当气候变化正在影响湖泊冰盖和热层化，从而影响深水氧气水平的时候。显然，管理者需要一个新的工具集，其中包括预测湖泊鲑鱼栖息地变化的预测模型，并提高对湖泊鲑鱼栖息地历史变化的理解。这项建议将大学研究人员和具有不同专业知识的合作伙伴(例如，建模师、工程师、生物学家、古生物学家)聚集在一起，开发和应用三种截然不同但互为补充的技术，以准确预测鲑鱼湖过去、现在和未来的深水溶解氧浓度。该项目还将为我们的学生和博士后提供出色的培训计划，融合多种但互补的方法，并与我们的跨学科支持组织和其他用户直接互动。在一个多压力因素的世界中，这些新颖的工具将为管理者提供一种科学地管理湖泊鲑鱼栖息地的方法，为缓解战略提供指导，并确保可持续管理。

Canada's Lake Trout lakes are a rare and valuable natural resource in both economic (in Ontario alone, anglers spend an estimated 1. 7 billion dollars on goods and services related to recreational fishing, with lake trout being the preferred species among many anglers) and ecological terms. However, lake trout populations are becoming increasingly threatened by multiple environmental stressors (e.g., over-exploitation, competition with introduced species, nutrient loading), with the added "threat-multiplier" of accelerated climate warming. There is growing concern that habitat quality in the deep waters of many Lake Trout lakes is declining due to oxygen depletion. Moreover, new evidence suggests that declines in deepwater oxygen concentrations may be occurring in lakes where nutrient inputs have not increased, or even where phosphorus inputs or lake nutrient concentrations have decreased over time, creating exceptions to the "increased nutrients, decreased deepwater oxygen paradigm". This is of particular concern because current approaches to resource management are prefaced on this major assumption, and thus are problematic in a multiple stressor world, and especially when climate change is affecting lake ice cover and thermal stratification, and consequently deepwater oxygen levels. It is clear that managers need a new toolset, one that includes predictive models for forecasting shifts in lake trout habitat and improves understanding of historical changes in lake trout habitat. This proposal brings together university researchers and partners with diverse expertise (e.g., modellers, engineers, biologists, paleolimnologists) to develop and apply three distinct, yet complementary, techniques to accurately predict past, present, and future deepwater dissolved oxygen concentrations in Lake Trout lakes. This project will also provide an outstanding training program for our students and post doc, blending diverse but complementary approaches, with direct interactions with our trans-disciplinary supporting organizations and other users. In a multiple-stressor world, these novel tools will provide managers with a scientifically-defensible approach for managing lake trout habitat, provide guidance on mitigation strategies, and ensuring sustainable management.