Ecological subsidies and ecosystem function: the role of dislodged seaweeds in the energy flow between coastal habitats

生态系统可以通过它们之间的能量和物质流动连接起来，这是捐助国和受援国之间的一种生态补贴形式。 在海洋沿岸带，从高产地区（如，岩石海岸、盐沼）到生产力极低的地区（例如，桑迪、泥滩）与通过移动的植物（例如，海藻，沼泽草）通过沿海水流。 通常情况下，波浪，特别是那些发生在风暴期间的波浪，是造成植物移位的干扰因素，但在高纬度地区，海冰的冲刷可能同样重要，甚至更重要。这一增加的生态因素可以改变生态补贴过程的动态，可能对依赖这一资源的较高营养水平产生影响。 虽然这种补贴在沿海生态系统中得到了广泛的承认和经常观察到，但这种能量转移发生的时空动态变化基本上没有记录。此外，冰冲刷扰动的作用完全未知。 然而，在圣劳伦斯海洋河口的初步工作表明，在海岸（被称为“残骸”）上堆积移位海藻的时间发生了戏剧性的变化，主要脉冲发生在春天。 该提案的总体目标是确定这种生态补贴的时空动态，包括评估以下方面的具体目标：（1）来源地区的当地海藻生产和驱逐海藻的对比干扰过程;（2）从这些来源地区驱逐海藻的运输及其在汇区的积累;以及（3）对动物聚集的影响（例如，无脊椎动物，鸟类）利用这一资源。本研究的第一个方面将使用时间序列，映射海藻床在床内的波浪力和冰冲刷的高分辨率措施串联解决。第二个方面将探讨首先使用现有的流通模式的粒子跟踪能力，以预测源和汇区之间可能的连接，然后通过释放和恢复的漂移卡经验验证模型的预测。最后一个方面将通过描述性和实验性工作进行研究，旨在记录海藻残骸沉积的模式并操纵其丰度，以确定残骸的空间和时间可用性如何影响食藻动物的种群动态（即，无脊椎动物如昆虫、蠕虫、甲壳类动物）和捕食者（例如，蜘蛛和鸟类）依赖于这种资源。 总体而言，拟议的研究将提供一个从摇篮到坟墓的视角，使我们能够预测补贴将如何应对环境变化，特别是气候引起的海冰动态变化。

Ecosystems can be connected by the flow of energy and material between them a form of ecological subsidy between donor and recipient areas. In marine coastal zones, habitats ranging from highly productive areas (e.g., rocky shores, salt marshes) to ones with extremely low productivity (e.g., sandy beaches, mud flats) form an interconnected mosaic with energy transferred by the transport of dislodged plants (e.g., seaweeds, marsh grass) by coastal currents. Typically waves, especially those occurring during storms, are the disturbance agents responsible for dislodging plants, but at higher latitudes scouring by sea ice can be equally or even more important. This added ecological factor can alter the dynamics of the process of ecological subsidies with possible consequences for the higher trophic levels that depend on this resource. Although such subsidies have been well recognized and frequently observed in coastal ecosystems, the variation in the temporal and spatial dynamics over which this energy transfer occurs remains largely undocumented. Moreover, the role of disturbance from ice scouring is entirely unknown. Preliminary work in the St. Lawrence maritime estuary has, however, shown a dramatic shift in the timing of the accumulation of dislodged seaweeds on the shore (known as “wrack”) with the dominant pulse occurring in the spring. The general objective of this proposal is to determine the spatio-temporal dynamics of this ecological subsidy, including specific objectives that assess (1) the local seaweed production in source areas and the contrasting disturbance processes dislodging seaweeds; (2) the transport of dislodged seaweeds from these sources areas and their accumulation in sink areas; and (3) the impacts on animal assemblages (e.g., invertebrates, birds) exploiting this resource. The first aspect of this study will be addressed using time series that map seaweed beds in tandem with high-resolution measures of wave forces and ice scouring within the beds. The second aspect will be explored first using the particle-tracking capacities of existing circulation models to predict the likely connections between source and sink areas, and then by the release and recovery of drift cards to empirically validate the model's predictions. The final aspect will be investigated by descriptive and experimental work aimed at documenting the patterns of the deposition of seaweed wrack and manipulating its abundance to determine how the spatial and temporal availability of wrack influences the population dynamics of the detritivores (i.e., invertebrates such as insects, worms, crustaceans) and the predators (e.g., spiders and birds) that depend on this resource. Overall, the proposed research will provide a cradle-to-grave perspective that will allow us to predict how subsidies will respond to environmental change, especially climate-induced changes to sea ice dynamics.