Using paleolimnology to assess the effects of multiple stressors on Boreal Shield lakes

淡水生态系统的结构、功能和生物多样性正受到多种环境压力的影响，这些压力往往以复杂的方式相互作用。需要一套不同的方法来了解内陆湖泊的这些应激源及其提供的生态服务(如娱乐、钓鱼、饮用水)的影响。例如，在最近的扰动开始之前对基线条件的了解可以用来区分新的趋势与自然变化或长期周期。此外，长期数据可用于将最近的变化置于历史背景下，为资源管理者提供现实的湖泊管理目标。为了提供一个长期的背景，我的研究将使用长期监测数据(季节到几十年)、空间调查和湖泊沉积物中保存的信息(几十年到几个世纪)的组合，来评估多种应激源对北方屏蔽湖水质和生物群落的独特和相互作用的影响。我和我的学生将探讨目前影响北方盾南部内陆湖泊的两个重要问题的驱动因素以及生态和管理影响：1)溶解有机碳浓度增加(即湖泊棕色化)；2)与道路盐应用相关的氯浓度增加。我对湖泊褐化的长期驱动因素的研究将用于更新预测模型，以评估土地利用变化和海岸线开发对湖泊鲑鱼湖深水氧气浓度的影响。这些模型由安大略省的资源经理每天使用，因为他们每年都会对1000个新的或重新开发的平房地块做出决策。鉴于最近的结果表明，目前的氯化物水质准则可能不足以保护营养贫乏的湖泊中的水生生物，也迫切需要对道路盐应用的生态阈值进行新的研究。最后，我的发现基金将培训8名HQP(4名研究生和4名本科生)，所产生的研究将有助于开发有效的湖泊管理指导方针和政策所需的新颖和可辩护的科学。

The structure, function and biodiversity of freshwater ecosystems are being altered by multiple environmental stressors that often interact in complex ways. A diverse set of approaches are needed to understand the impacts of these stressors of inland lakes, and on the ecological services they provide (e.g., recreation, fishing, drinking water). For example, an understanding of baseline conditions prior to the onset of recent disturbances can be used to distinguish novel trends from natural variability or long-term cycles. Moreover, long-term data can be used to place recent changes in a historical context, providing realistic lake management targets for resource managers. To provide a long-term context, my research will use a combination of long-term monitoring data (seasons to decades), spatial surveys, and information preserved in lake sediments (decades to centuries), to assess the unique and interactive effects of multiple stressors on water quality and biological communities in Boreal Shield lakes. My students and I will explore the drivers and the ecological and management implications of two important issues presently affecting inland lakes within the southern Boreal Shield: 1) increasing dissolved organic carbon concentrations (i.e., lake brownification); and 2) increasing chloride concentrations associated with road salt applications. My research on the long-term drivers of lake brownification will be used to update predictive models for assessing impacts of land-use change and shoreline development on deep water oxygen concentrations in lake trout lakes. These models are used daily by resource managers in Ontario, as they make decisions regarding >1000 new or redeveloped cottage lots per year. New research that quantifies ecological thresholds from road salt application is also urgently needed, given recent results showing that current water quality guidelines for chloride may not adequately protect aquatic life in nutrient-poor lakes. In closing, my Discovery Grant will train eight HQP (four graduate and four undergraduate students), and the research generated will contribute the novel and defensible science needed to develop effective lake management guidelines and policies.