Resource partitioning in the St. Lawrence estuary

这个nserc支持的研究项目的长期目标是阐明河口过渡带（淡水首先与海水混合的地方）的高度异质性环境是如何影响河口鱼类的生态和进化的。我们建议实现四个主要目标。首先是评估在开发过程中对河口景观的开发如何产生选择性力，从而导致圣劳伦斯河口两个同域种群的独立表型轨迹。我们将对两个种群从孵化到繁殖（3岁以上）的两个队列进行采样，从而提供纵向发育系列，包括生长、形态发育、生存和性成熟，以及纵向和纵向深度、盐度和温度梯度的函数。第二个具体目标是验证这样一种假设，即东太平洋经济区最丰富的鱼类——小鳕，在形态上专门用于开发深通道和浅滩栖息地，并表现出与同域鱼群相似的形态差异。我们的第三个具体目标是利用相同的采样程序来描述整个鱼类群落的空间结构作为ETZ物理梯度的函数。第四个具体目标是把重点放在另一个工具上，我们希望利用这个工具揭示资源在空间和时间尺度上的划分。碳、氮和硫的稳定同位素分析将用于确定幼鱼和1+鱼的取食空间范围。同样的分层抽样计划涉及跨越经济经济区环境梯度的30个站点的网格，将有助于绘制所有关键过渡区鱼类所有生活史阶段的分布图。由于新的采样平台（Lampsilis）的可用性，这些目标得以实现，该平台允许对浅水和深水栖息地进行采样，并结合使用了包括稳定同位素分析和分子遗传学在内的创新技术。

The long term objective of this NSERC-supported research program has been to elucidate how the highly heterogeneous environments that characterise the estuarine transitional zone (where freshwater first mixes with seawater) influence the ecology and the evolution of estuarine fishes. We propose to pursue four major objectives. The first is to assess how the exploitation of the estuarine landscape during development generates the selective forces leading to independent phenotypic trajectories of two sympatric populations of smelt in the St. Lawrence estuary. We will sample two cohorts of smelt of both populations from hatching to reproduction (age 3+), thus providing a longitudinal developmental series for growth, morphological development, survival and sexual maturation as a function of depth, salinity and temperature gradients along transversal and longitudinal axes. The second specific objective is to test the hypothesis that tomcod, the most abundant fish of the ETZ, are morphologically specialized to exploit deep channel and shallow shoal habitat and exhibit a morphological divergence similar to that of the sympatric populations of smelt. Our third specific objective is to exploit this same sampling program to describe the spatial structure of the entire fish community as a function of the ETZ's physical gradients. The fourth specific objective is to focus on another tool with which we hope to reveal the partitioning of resources on a spatial and temporal scale. Stable isotope analyses of carbon, nitrogen and sulphur will be used to define the spatial extent of feeding of young-of-the-year and 1+ fishes. The same stratified sampling plan involving a grid of 30 stations spanning the environmental gradients of the ETZ will serve to map the distribution of all life history stages of all key transitional-zone fishes. These objectives are attainable thanks to the availability of a new sampling platform (the Lampsilis), which permits the sampling of shallow and deep-water habitat, and the use of a combination of innovative technologies including stable isotope analysis and molecular genetics.