"Life under the ice" - winter ecology of temperate rivers

加拿大的水生环境暴露在温度、生产力和食物供应的极端季节性变化中。然而，令人惊讶的是，我们对河流生态系统生态功能的了解绝大多数来自于在无冰月份进行的研究，对这些生态系统在冬季如何运作的了解非常少。因此，随着冬季冰盖时间变短，我们缺乏基本知识来确定生态系统功能的哪些组成部分正在丧失以及如何减轻这些影响。在接下来的5年里，我将进行一项实地研究计划，以a)确定河流群落的冬季生态，表征冰盖河流的食物网结构和生态系统功能，以及b)评估气候变化可能如何改变这些相互作用和影响生态系统功能。 在目标1中，MSc1、2、3和I将在新不伦瑞克的河流中进行季节性(秋季、冬季和春季)采样，以评估河流群落结构和功能的季节性变化。MSc1和我将使用稳定同位素分析、层析、显微镜和DNA分析来评估生物膜的群落结构和营养质量的季节变化，生物膜是温带河流食物网的基础。MSc2和我将使用数量生态学和稳定同位素分析来确定无脊椎动物群落结构和资源利用的季节变化。MSc3和我将使用食物和稳定同位素分析来评估冰盖河流中支持鱼类群落的营养生态和能量途径。 在目标2中，博士1和我将在8条新不伦瑞克河流中使用目标1中开发的方法，这些河流的纬度梯度相当于年平均温度2摄氏度，其中包括4条地下水补给的河流，这些河流在冬季几个月里保持不结冰。我们将在每个地点对初级生产者、水生无脊椎动物和鱼类进行季节性采样，并结合稳定同位素分析、脂肪酸分析和数量生态学，以确定冬季长度和强度的变化如何影响温带河流食物网的结构和功能。 该项目将培训4名研究生和9名本科生HQP，并将对河流生态系统功能的季节变化提供独特的见解。这项工作将通过发展一种新的描述水生群落结构和功能之间联系的新特征来推进生态学领域，其中纳入了河流环境的季节性变化。此外，它还将提供一种更好的方法来预测气候变化对河流群落的影响，并建立一个可以应用于加拿大温带河流的模型。

Aquatic environments in Canada are exposed to extreme seasonal variation in temperature, productivity and food availability. Surprisingly however, our understanding of the ecological function of river ecosystems is overwhelmingly derived from studies conducted during the ice-free months and remarkably little of known regarding how these ecosystems function during winter. Hence, as periods of winter ice cover become shorter we lack the fundamental knowledge to determine what component of ecosystem function is being lost and how to mitigate these effects. Over the next 5 years, I will conduct a field-based research program to a) determine winter ecology of river communities, characterising the food web structure and ecosystem function of ice-covered rivers and b) assess how climate change may modify these interactions and influence ecosystem function. In Objective 1, MSc1, 2, 3 and I will conduct seasonal (fall, winter and spring) sampling in rivers in New Brunswick to assess seasonal variation in the community structure and function of river communities. MSc1 and I will use stable isotope analysis, chromatography, microscopy and DNA analysis to assess seasonal variation the community structure and nutritional quality of biofilm, the base of temperate river food webs. MSc2 and I will use quantitative ecology and stable isotope analysis to determine seasonal variation in the community structure and resource use of invertebrate communities. MSc3 and I will use diet and stable isotope analysis to assess the trophic ecology and energy pathways supporting fish communities in ice covered rivers. In Objective 2, PhD1 and I will employ the methods developed in Objective 1 in eight New Brunswick rivers spanning a latitudinal gradient equating to a 2C range in mean annual temperature and including four groundwater fed rivers which remain ice free during winter months. We will conduct seasonal sampling of primary producers, aquatic invertebrates and fishes at each site and use a combination of stable isotope analysis, fatty acid analysis and quantitative ecology to identify how variation in length and intensity of winter influences the structure and function of temperate river food webs. This program will train 4 graduate and 9 undergraduate HQP and will provide a unique insight into seasonal variation in river ecosystem function. This work will advance the field of ecology by developing a novel characterization of the links between structure and function of aquatic communities which incorporates seasonal changes in the river environment. In addition, it will provide a better method to predict the effect of climate change on riverine communities and establish a model which can be applied to temperate rivers across Canada.