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

通过河道移动的沉积物起到了载体的作用，将营养物质和污染物沿同一路线移动到下游湖泊。一些可溶性化学物质松散地吸附在沉积物上，而其他物质则物理地附着在细沉积物上。细无机沉积物的定义是小于63微米，它很容易与水柱中的有机颗粒结合，形成比其组成物质更大且具有不同沉降特性的聚集或絮凝颗粒。这导致沉积物和附着有机物的迁移和沉降速率变化不定，因此难以预测。以鲑鱼腐烂产物为例，本研究探讨了沉积物和鲑鱼的相互作用，改变了鲑鱼来源的营养物质（SDN）从产卵地到下游苗圃湖的输送。在不列颠哥伦比亚省内陆，鲑鱼苗圃湖泊需要初级生产水平，以维持食物网，以支持鲑鱼鱼苗。返回产卵鱼的腐烂产物对下游苗圃湖初级生产的贡献程度尚不确定。鲑鱼腐烂营养物质的命运影响着产卵地的管理，并可能影响到未来鱼群的成功。在捕获高密度和低密度产卵鱼返回的5年期间，我建议I)估计在产卵场和苗圃湖之间通过河流排放转移的渠道储存的SDN的数量和时间，ii)量化上游河道和漫滩储存的SDN，以及iii)测量和模拟与产卵流排入苗圃湖相关的物理混合过程，以确定SDN负荷对苗圃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.