Zooplankton trophodynamics and spatial patterns in estuarine transition zones

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。本研究计划旨在通过考虑河口景观空间离散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，了解次生（浮游动物）生产力的控制。一些相互关联的短期目标将被解决，重点关注圣劳伦斯河口过渡带的营养层动力学和栖息地连通性的特定方面：(1)将确定一年中不同时间沿河口（例如盐度）和跨河口（浅滩与深水栖息地）排列的栖息地中浮游动物组合的季节性演变。(2)通过关注不同生境类型物种组合的营养联系来确定次生生产。(3)对潜在补贴和生境间的营养耦合程度进行量化，重点关注在能量转移中起主要作用的物种子集。(4)将利用现场和实验室试验来测量营养联系的速率和强度。(5)从长远来看，我们的目标是建立一个耦合的生物-物理模型，以估计原位本地生产和栖息地之间的补贴运输对总体河口二次生产的相对重要性。本研究提出了两个主要的研究项目，一个是研究河口过渡带异质空间中浮游动物的总体生产、放牧和捕食。二是研究优势桡足类与中等大小捕食者（足虫）之间的时空变异及其原因和关系对总体次生生产力的重要性。

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. This research program aims to understand the control of secondary (zooplankton) productivity by considering the degree of trophic connectivity among spatially discrete habitats of the estuarine landscape and how such exchanges vary on a seasonal scale. A number of interrelated short-term goals will be addressed, focussing on particular aspects of tropho-dynamics and habitat connectivity in the estuarine transition zone of St Lawrence Estuary: (1) Seasonal succession of zooplankton assemblages in habitats arrayed along (e.g., salinity) and across (shoal vs. deep habitats) the estuary at different times of the year will be determined. (2) Secondary production by focussing on trophic linkages within species assemblages of various habitat types will be determined. (3) Potential subsidies and the degree of trophic coupling among habitats will be quantified, focussing on a subset of species that play a major role in energy transfer. (4) Rates and strength of trophic linkages will be measured using in situ and laboratory experiments. (5) In the longer term, we aim to develop a coupled biological-physical model to estimate the relative importance of in situ local production and subsidy transport among habitats to overall estuarine secondary production. This research proposes two main projects, one focussing on overall zooplankton production, grazing and predation of zooplankton in the heterogeneous space of the estuarine transition zone. The second one focuses on temporal and spatial variability, its causes and importance of relationships between dominant copepods and intermediate sized predators (mysids) to overall secondary productivity.