Riverscape structure and ecological processes

景观生态学引起了人们对景观结构(如地形、土地利用)与生态功能(如光合作用)之间的密切联系的关注。在大型河流中，支流是影响河流主干属性(如流量、泥沙负荷)的关键景观要素，并导致环境条件的梯度，如有机物含量和水下光照气候。我们在此提出了圣劳伦斯河(SLR)的“河景”方法，其中水下光谱组成(“水色”)代表了表征河流景观结构特性的一个综合变量，而这反过来又决定了关键的自养生态功能。因此，这项研究提案的首要目标是解决河流生态系统结构(基于水下光谱特性)如何由生境之间的连通性(物质转移)决定，以及它如何影响SLR的关键生态功能，如浮游植物初级生产、呼吸和生物多样性，以及浮游植物向初级消费者的营养转移。此外，这种河景方法将允许广泛的基于过程的自养功能的视角，因为从遥感获得的表面颜色观测与现场测量的水下光谱组成之间存在强烈的关系，正如我们最近为单反所证明的那样。这一发现现在为大河的纬度比较提供了一个新的视角。拟议的研究还将提供重要的基线信息和监测未来环境变化(例如全球变暖或有毒废物排放)的方法，从而有助于对受人类影响的流水生态系统的生产机制和生物多样性有一个全面的了解。该项目将为研究生培养提供绝佳的机会。它将涉及五名研究生：两名博士，三名硕士，九名暑期和三名兼职理科学生。通过这一系列研究项目，我的实验室将提供湖泊学方面的高级培训，重点是大河生态学、水文学、生物光学、微生物生态学和生态生理学。

Landscape ecology has drawn attention to the close linkages between landscape structure (e.g. topography, land use) and ecological function (e.g. photosynthesis). In large rivers, tributaries constitute a key landscape element affecting attributes of the main stem of the river (e.g. flow rate, sediment load) and causing gradients in environmental conditions such as organic matter content and the underwater light climate. We here propose a 'riverscape' approach to the St.Lawrence River (SLR) where underwater spectral composition ("water color") represents an integrative variable for characterizing the structural properties of the riverscape, and which in turn determines key autotrophic ecological functions. The overarching goal of this research proposal is thus to resolve how river ecosystem structure (based on underwater spectral properties) is determined by the connectivity (transfer of matter) between habitats, and how it affects key ecological functions of the SLR such as phytoplankton primary production, respiration and biodiversity and the trophic transfer from phytoplankton to primary consumers. Furthermore, this riverscape approach will allow a broad scale perspective of process-based autotrophic functions because of the strong relationship between surface color observations from remote-sensing and measured in situ underwater spectral composition, as we have recently demonstrated for the SLR. This finding now provides a new perspective for latitudinal comparisons of large rivers. The proposed research will also contribute to a general understanding of production mechanisms and biodiversity in human-impacted, flowing water ecosystems by providing important baseline information and approaches for monitoring future environmental change (e.g. global warming or toxic waste discharge). This program will provide outstanding opportunities for graduate student training. It will involve five graduate students: two PhD, three MSc, nine summer and three part time BSc students. Through this coupled set of research projects, my laboratory will provide advanced training in limnology with emphasis on large river ecology, hydrology, bio-optics, microbial ecology and ecophysiology.