Paleolimnology and Environmental Change

上个世纪的气温升高以及对今后20-50年气温将空前上升的预测，使人们对气候变化对水生生态系统的潜在影响感到关切。我实验室的研究重点是通过分析湖泊沉积物岩心中保存的物理、化学和生物信息，了解湖泊在过去是如何对气候和其他自然或人为因素做出反应的。 古湖沼学研究可以提供关于水生和陆地生态系统对气候变化敏感性的重要见解。该提案旨在提供研究和培训机会，以调查过去较暖时期如何影响北方安大略北部湖泊的水平衡和水产生产，重点是全新世最高温期，这是大约8 000至4 000年前的较暖时期。在HTM，西北部安大略的特点是一个公园型森林灌木和草，低湖水位，和频繁的火灾。然而，在北方安大略从苏族瞭望台到蒂明斯（距离超过700公里）的潮湿地区，湖泊如何对HTM作出反应的信息在很大程度上是未知的。HTM很可能影响了整个地区，因为在安大略北方最东部的蒂明斯附近，白松取代了云杉。7,000年前，在回到大约4,000年前的云杉林之前。我们建议开发和应用的方法，使用物理，化学和生物代理，从近岸和深水的核心，提供信息，如何湖的水平和生产的中部和东部北部地区的安大略的变化，以及提供信息，植被和火灾的变化在全新世。鉴于HTM期间估计的温度变化相对于预计的变暖较小，本研究的信息将提供对可能的干旱，藻类水华和与生活在更温暖的世界相关的火灾的脆弱性的评估。 该提案还寻求支持，以提供培训和研究机会，了解最近的气候变化对阿迪朗达克地区（美国纽约）湖泊的可能作用。东北部的大多数水生系统现在受到多种地方和区域压力的影响。 我们开发了一个由31个参考湖泊组成的网络，这些湖泊是从1400多个湖泊中选出的，它们几乎不受当地人类活动（道路、伐木、定居、鱼类放养）和酸沉降的直接影响。将对这一湖泊网络进行研究，以评估在东北部水生系统缺乏最常见的环境压力因素（即酸沉积、流域干扰、鱼类放养）的情况下，藻类和无脊椎动物的生物组合是如何变化的，从而可以评估与气候和其他大规模区域压力因素有关的近期变化。 **

Warmer temperatures over the last century and projections of unprecedented increases in temperature over the next 20-50 years, has led to concern on the potential impacts of climate change on aquatic ecosystems. Research in my lab focuses on understanding how lakes have responded to climate and other natural or human-induced factors in the past, by the analysis of the physical, chemical and biological information preserved in lake sediment cores. Paleolimnological studies can provide important insights on the sensitivity of aquatic and terrestrial ecosystems to climate change. This proposal seeks to provide research and training opportunities to investigate how warmer periods in the past influenced the water balance and aquatic production of boreal lakes from northern Ontario, with a focus on the Holocene Thermal Maximum (HTM), a warmer period circa 8,000 to 4,000 years ago. During the HTM, northwest Ontario was characterized by a parkland-type forest with scrubs and grasses, low lake-levels, and frequent fires. However, information on how lakes responded to the HTM, across the humid regions of northern Ontario from Sioux Lookout to Timmins (a distance of over 700 km) are largely unknown. It is likely that the HTM influenced this entire region, since the easternmost region of northern Ontario, near Timmins, saw white pine replacing spruce c. 7,000 years ago, before returning to a spruce forest circa 4,000 years ago. We propose to develop and apply approaches, using physical, chemical and biological proxies, from both near-shore and deep-water cores, to provide information on how lake levels and production changed across the central and eastern boreal regions of Ontario, as well as provide information on changes in vegetation and fire over the Holocene. Given that the estimated temperature changes during the HTM were small relative to the projected warming, information from this study will provide an assessment of vulnerability to possible droughts, algal blooms, and fires associated with living in a warmer world.**** This proposal also seeks support to provide training and research opportunities to understand the possible role of recent climate change on lakes from the Adirondack region (New York, USA). Most aquatic systems in the northeast are now influenced by multiple local and regional stressors. We have developed a network of 31 reference lakes, that were chosen from over 1400 lakes, to have little impact from local human activities (roads, logging, settlement, fish stocking) and the direct impacts of acid deposition. This network of lakes will be studied to assess how biological assemblages of algae and invertebrates have changed in the absence of the most common environmental stressors to aquatic systems in the northeast (i.e. acid deposition, watershed disturbances, fish stocking), thereby allowing an assessment of recent changes related to climate and other broad-scale regional stressors.**** **