Anthropogenic impacts on river food webs

南艾伯塔省是一个严重缺水的地区，那里所有的水生资源都受到相当大的人为影响。此外，由于湖泊的短缺，这个地区在水生食物网方面已经做了大量的工作。一个长期目标是解决与河流食物网合作的空间问题(无论是方法上还是理论上)。这些问题源于河流的线性几何形状，以及它们通常是开放的等级系统，几乎在每个属性(如温度、营养物质、例如，食物网的物种组成和动态正在沿着河流连续体逐渐变化。该提案概述了与河流食物网结构和功能有关的三个项目：(1)SSRB食物网中的汞生物放大。需要在流域内使用嵌套比较方法回答的问题是：(A)沿河汞暴露的梯度是什么；(B)作为潜在汞来源的活动，如煤炭开采、集约化农业、灌溉和污水，有多重要；以及(C)顶级捕食者中的汞水平是否可以通过局部暴露和生物放大来解释，或者，通过下游地区的鱼类运动进行生物运输是一个重要因素。(2)引进虹鱼和本地割喉鲑鱼杂交的生态后果。在许多西部河流的源头地区，食源性鲑鱼主宰着食物网。彩虹鲑鱼的放养导致了迅速扩大范围的杂交品种的形成和传播，留下了极少的基因纯种鲑鱼种群。这项研究将探索杂交鲑鱼和本地割喉鲑鱼之间的生态差异及其功能后果。3.)生活和动物污水中的有机物质和营养物质及其对河流食物网的影响。在这个项目中，我们将使用稳定同位素来追踪这些来源的食物网浓缩的程度和程度。

Southern Alberta is an area of acute water scarcity, where all aquatic resources are subjected to considerable anthropogenic influence.  In addition, it is an area, due to the shortage of lakes, where very work on aquatic foodwebs has been done.   A long-term goal is to address the spatial problems (both methodological and theoretical) of working with riverine food webs.  These arise from the linear geometry of rivers and the fact that they are usually open-ended hierarchical systems with strong directionality and strong upstream/downstream gradients in virtually every attribute (eg temperature, nutrients, and productivity).  As such the species compostion and dynamics  of the foodweb is gradually changing along the river continuum.   The proposal outlines three projects related to river food webs structure and function   (1)Mercury biomagnification in the SSRB food web.  The questions to be answered using a nested comparative approach within the watershed, are: (a) What is the gradient in mercury exposure along the river, (b) how important are activities such as coal mining, intensive agriculture, irrigation, and sewage as potential mercury sources, and (c) can levels of mercury seen in top predators be explained by local exposure and biomagnification, or is biotransport through fish movements from downstream areas an important factor.   (2)Ecological consequences of hybridization between introduced rainbow trout and native cutthroat trout. Cutthroat trout dominate the foodwebs of the headwater regions of many western rivers. Rainbow trout stocking has resulted in the formation and spread of hybrids that are rapidly expanding their range leaving very few genetically pure cutthroat trout populations. This study will explore ecological differences between hybrids and native cutthroat trout and their functional consequences. 3.)Organic matter and nutrients from domestic and animal sewage and its impact on river food webs.  In this project we will use stable isotopes to trace the magnitude and the extent of foodweb enrichment from these sources.