Sediment and Salmon Interactions: Implications for nutrient storage and downstream lake productivity

流经河道的沉积物起到了载体的作用，将营养物质和污染物沿着相同的路线输送到下游湖泊。一些可溶的化学物质松散地吸附在沉积物上，而另一些物质则物理地附着在细小的沉积物上。细小的无机沉积物定义为小于63微米，很容易与水柱中的有机颗粒结合，形成聚集或絮凝的颗粒，这些颗粒比它们的组成物质更大，具有不同的沉降特性。这导致沉积物和附着的有机物质的输运和沉降速率不稳定，因此预测很差。本研究以鲑鱼腐烂产品为例，研究了沉积物与鲑鱼之间的相互作用对产卵场向下游育苗湖输送鲑鱼营养物质(SDN)的影响。在不列颠哥伦比亚省的内陆，鲑鱼苗圃湖需要一定水平的初级生产量来维持食物网，以支持鲑鱼鱼苗。目前还不确定返回产卵者的腐烂产物在多大程度上对下游托儿所湖泊的初级生产力做出了贡献。鲑鱼腐烂营养物质的命运对产卵场的管理和未来种群的成功有着潜在的影响。在捕获高密度和低密度产卵者回报的5年时间里，我建议：i)估计产卵场和育儿湖之间河流流量中渠道储存的SDN的数量和时间；ii)量化上游河道和泛滥平原SDN的储存；iii)测量和模拟与产卵溪流排入育儿湖的物理混合过程，以确定SDN负荷对育儿湖初级生产力的影响。

Sediment moving through river channels acts as a vector, moving nutrients and contaminants along the same route to downstream lakes. Some soluble chemicals are loosely adsorbed to the sediment while other material is physically attached to the fine sediment. Fine inorganic sediment, defined as being smaller than 63 microns, readily combines with organic particles in the water column to form aggregated or flocculated particles which are larger and have different settling properties than their constituent materials. This results in variable, and therefore poorly predicted, transport and settling rates for both the sediment and the attached organic matter. Using salmon decay products as a contemporary example, this study investigates the interaction of sediment and salmon in altering the delivery of salmon-derived nutrients (SDN) from the spawning grounds to the downstream nursery lakes. In the interior of BC, salmonid nursery lakes require levels of primary production that can maintain the food web to support salmon fry. It is uncertain to what degree the decay products of returning spawners contribute to primary production in downstream nursery lakes. The fate of salmon decay nutrients has implications in the management of the spawning grounds and potentially for the success of future stocks. Over a 5-year period, which captures high- and low-density spawner returns, I propose to i) estimate the amount and timing of channel-stored SDN transferred in river discharge between the spawning grounds and nursery lake, ii) quantify the upstream river channel and floodplain storage of SDN, and iii) measure and model the physical mixing processes associated with a spawning stream emptying into a nursery lake in order to determine the effects of SDN loads on nursery lake primary productivity.