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单位组成的开放系统。这些亚单位包含随时间变化的食物网，其营养相互作用提供了能量和物质从较低营养水平到消费者和捕食者的途径。与此同时，环境空间复杂性和通过主动和被动运输过程（例如，生物体的分散，通过资源的能量运输）的相互联系现在被认为可以改变种群和群落的动态，并最终维持生物多样性。我们建议在圣劳伦斯河口的河口过渡带工作，这是一个重要的鱼类苗圃，由高产量的自养和异养浮游生物支持。然而，我们仍然没有完全理解所涉及的过程。由于上层海洋和底栖食物网通过营养和能量流动紧密耦合，我们的目标是通过考虑河口景观栖息地之间的营养连通性程度以及这种交换在季节尺度上的变化，了解河口食物网（上层海洋和底栖）中有机物转移的生态重要性。为了实现我们的科学目标，我们要求两次采样巡航（2010年6月和8月），每7天，在“兰普西利斯”号研究船上，提供了在浅海沿岸地区和较深的通道取样的可能性。为了覆盖一个重要的空间尺度，我们的团队，由来自UQAR和UQAC的研究人员和学生组成，将沿着环境梯度取样，从非常浅的海湾到河口过渡带的两个不同盐度带的水道栖息地。为了追踪元素循环的细节，我们将使用稳定的碳和氮同位素分析从颗粒有机物，动物园和鱼类浮游生物以及底栖大型和小型动物。

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.