Ecosystem function in changing environments: an integrative approach to modeling the control of genetic biodiversity and secondary productivity by hydrodynamic circulation

由于人类活动和自然过程的结合，沿海环境的生态系统受到严重压力。圣劳伦斯河口（SLE）是加拿大最大的河口，也是受污染和过度捕捞等一系列压力因素影响最严重的河口。这个生态系统的主要特征是循环模式——水流和潮汐的结合，既创造了具有独特特征的水体，也运输了永久或暂时生活在水柱中的生物（即底栖无脊椎动物的幼虫）。因此，循环模式将通过创造一种能够支持遗传多样性和当地种群稳定的异质环境以及通过控制个体在种群之间的分散，对物种的种群结构产生深远的影响。最终，这些效应将影响次生生产，次生生产是维持食物网结构和能量流的关键生态系统功能。本文研究了沿海和近海环流对河口桡足类、海洋桡足类和海洋贻贝这三种主要无脊椎动物种群结构和次生生产的影响，这三种动物共同构成了SLE次生生产的基础。同时，我们将描述这些物种的遗传和人口结构，研究这些结构如何与SLE的水文结构相对应，并记录这种结构对生态生理性能的影响。然后，我们将利用这些信息开发能够预测不同环境情景下次生生产力的模型，包括与气候变化相关的情景（例如，淡水排放改变）。我们预计，循环模式将对人口结构产生巨大影响，同时对次生生产产生影响，这对确定管理单位的空间尺度和时间稳定性至关重要，是制定保护加拿大生态系统健康的政府环境政策的重要过程。

Coastal environments are severely stressed ecosystems due to a combination of human activities and natural processes.  The St. Lawrence estuary (SLE) is Canada's largest and most heavily impacted estuary due to a suite of stressors including pollution and over-fishing.  The keystone feature underlying this ecosystem is the pattern of circulation - the combination of currents and tides that both create water masses of distinct characteristics and transport organisms living in the water column either permanently or temporarily (i.e., the larvae of benthic invertebrates).  Circulation patterns will thus have profound effects on the population structure of species both by creating a heterogeneous environment that can support genetic diversity and local population stability and by controlling the dispersal of individuals between populations.  Ultimately these effects will influence secondary production, a key ecosystem function in the maintenance of food web structure and energy flow.  Here we propose to examine the influence of coastal and off-shore circulation on the population structure and secondary production of three key invertebrates, an estuarine copepod, a marine copepod, and a marine mussel, that together form the basis of secondary production in the SLE.  In parallel, we will describe the genetic and demographic structure of these species, examine how any such structure corresponds to hydrographic structures of the SLE and document the effect of this structure on ecophysiological performance. We will then use this information to develop models capable of predicting the secondary productivity under different environmental scenarios, including those associated with climate change (e.g., altered freshwater discharge).  We anticipate circulation patterns will have large effects on population structure with concomitant effects on the secondary production, a consequence of key importance in identifying the spatial scales and temporal stability of management units, a vital process in the development of governmental environmental policies for protecting the health of Canadian ecosystems.