Trophic transfer of organic matter along environmental gradients in an important nursery zone of the St. Lawrence estuary

生态系统被认为是由相互关联的异质亚基组成的开放系统。这些亚基包含随时间变化的食物网，其营养相互作用提供了从较低营养水平到消费者和捕食者的能量和物质的途径。与此同时，环境空间复杂性和通过主动和被动运输过程的相互联系（例如，生物体的分散、通过资源的能量运输）现在被认为改变了种群和群落的动态，并最终维持了生物多样性。在这里，我们建议在圣劳伦斯河口的河口过渡区，一个重要的苗圃区的鱼类，是由一个高生产力的自养和异养浮游生物的支持。然而，我们仍然没有完全理解所涉及的过程。由于浮游和底栖食物网是紧密耦合通过营养和能量流，我们的目标是了解生态的重要性，有机物转移河口食物网（浮游和底栖）考虑河口景观的栖息地之间的营养连接程度，以及如何在季节性尺度上变化的交流。为了实现我们的科学目标，我们请求在“Lampsilis”号研究船上进行两次取样航行（2010年6月和8月），每次为期7天，该船可以在浅沿岸的区域以及较深的水道中取样。为了覆盖一个重要的空间尺度，我们的团队，由研究人员和学生从UQAR和UQAC组成，将采样断面沿着环境梯度从非常浅的海湾通道栖息地在两个不同的盐度区的河口过渡带。为了追踪元素循环的细节，我们将使用来自颗粒有机物、浮游动物和鱼类以及底栖大型和小型动物的稳定碳和氮同位素分析。

Ecosystems are considered to be open systems composed of inter-related heterogeneous subunits. These subunits contain food webs that vary in time and whose trophic interactions provide the pathways of energy and matter from lower trophic levels to consumers and predators. At the same time environmental spatial complexity and interconnectivity via active and passive transport processes (e.g., dispersion of organisms, energy transport through resources) are now recognized to alter population and community dynamics and ultimately maintain biological diversity. We propose here to work in the estuarine transition zone of the St. Lawrence estuary, an important nursery zone for fishes that is supported by a high productivity of autotrophic and heterotrophic plankton. However, we still do not completely understand the processes implicated. Since pelagic and benthic food webs are tightly coupled through nutrient and energy flow, our objective is to understand the ecological importance of organic matter transfer within the estuarine food web (pelagic and benthic) by considering the degree of trophic connectivity among habitats of the estuarine landscape and how such exchanges vary on a seasonal scale. To achieve our scientific objective, we request two sampling cruises (June and August 2010), each 7 days, on the research vessel "Lampsilis" that offers the possibility to sample in shallow littoral zones as well as in deeper channels. To cover an important spatial scale our team, composed of researchers and students from UQAR and UQAC, will sample transects along environmental gradients from very shallow bays to channel habitats in two distinct salinity zones of the estuarine transition zone. To trace details of element cycling, we will use stable carbon and nitrogen isotope analyses from particulate organic matter, zoo- and ichthyoplankton as well as benthic macro and meiofauna.